JP6139749B2 - Cast-in-place pile method - Google Patents

Description

  The present invention relates to a cast-in-place pile method for building a foundation pile such as a building.

Conventionally, a cast-in-place pile construction method is known as a foundation construction method for constructing a foundation pile such as a building.
In the cast-in-place pile method, there is a cast-in-place concrete pile method in which a drill hole is formed in the ground by an excavator and concrete is poured into the drilled hole.

It is necessary to build a cast-in-place concrete pile by improving the pile support force by such a construction method, and the tip support force coefficient is used as an index of the yield strength per unit area on the tip side of the cast-in-place concrete pile.
In the cast-in-place concrete pile, the tip supporting force coefficient is set to α = 150 kN / m ² .

In recent years, a tip preload cast-in-place pile method that can improve the tip supporting force of the concrete pile by 30 to 40% by consolidating the looseness of the ground on the pile tip side has been used (for example, Patent Document 1). Described in).
In this method, after the pile concrete of the cast-in-place concrete pile is hardened, cement milk is pressurized and injected from the ground into the injection bag that is attached to the tip of the rebar cage, the slime is removed from the pile tip, and the ground is strengthened. This is a method for reducing the amount and improving the supporting force, and is a method for improving the tip supporting force as compared with the conventional method.

In addition to the tip support force, a construction method for improving the peripheral surface support force of the cast-in-place concrete pile and the peripheral surface friction force has been proposed.
For example, Patent Document 2 discloses that in placing concrete in a cast-in-place concrete pile, an inflatable material whose hardening is delayed from the pile concrete body is disposed on the peripheral surface of the pile, and the inflatable material expands. A method for improving the peripheral surface supporting force and increasing the peripheral frictional force by forming a bulge on the peripheral surface of the pile is disclosed.
Patent Document 3 describes a cast-in-place concrete pile by mixing a hardening retarder with a solidifying agent such as cement and attaching an expansion member that increases the peripheral friction of the pile to the cover portion (outer peripheral portion) of the cast-in-place concrete pile. A construction method that increases the peripheral frictional force by generating and expanding the expansion member at the cover portion of the pile is disclosed.

Japanese Patent No. 3926364 Japanese Patent No. 4111432 Japanese Patent No. 4155843

However, when normal concrete is placed in the excavation hole, when the concrete hardens, the entire concrete pile contracts, or the ground loosens during excavation, and the contact force between the concrete pile and the excavation hole ground is related. It became weak, and looseness and a gap were generated between the outer peripheral surface of the concrete pile and the inner wall surface of the excavation hole.
This looseness and clearance also led to a decrease in the tip support force on the tip side of the concrete pile, a decrease in the peripheral friction force on the outer wall surface of the concrete pile, and a decrease in the pulling resistance force.
Therefore, the function deterioration of the whole concrete pile was invited.

  Moreover, in the said tip preload cast-in-place pile method of patent document 1, the process of twice construction of the process of placing a concrete pile main body and the process of pressurizing cement milk after hardening of a concrete pile main body is required In addition, since it takes a lot of time for the concrete to harden and time for the cement milk to harden, it has a problem that it takes a lot of time to show the performance of the pile.

Moreover, in the concrete pile construction method of the said patent document 2, since all are the construction methods in which an expansive material expand | swells after a concrete pile hardens | cures, considerable time is required to show the performance of a concrete pile. It was.
Moreover, since it has a structure in which an inflatable material is arranged around the pile body that is the foundation of the concrete pile, it is difficult to position the inflatable material in the middle as it is, and the concrete pile body and It was necessary to apply the expandable material twice.

  Furthermore, the concrete pile construction method described in Patent Document 3 is a construction method in which the expansion member is hardened while being expanded behind the hardening of the concrete of the pile body, and therefore it takes a considerable amount of time to exhibit the performance as a concrete pile. Was.

  Moreover, in the concrete construction method described in Patent Document 3, since the expansion member is hardened while expanding after the hardening of the pile concrete, particularly when the excavation depth is deep, the pile tip portion of the drilled ground Near the tip and under the high water pressure under the groundwater, the expansion member to which the foaming agent is added to the outer periphery of the pile concrete is subjected to high water pressure, the expansion of the expansion member is suppressed, the pile peripheral surface friction force and the pile tip There was a possibility that the effect of improving the bearing capacity would be reduced.

  The present invention has been made in view of such circumstances, and by placing an expanding cement fluid to which a foaming agent having an expansion action is added even in a drilling hole having a deep excavation depth, the cement fluid is provided. Provides a cast-in-place pile construction method that sufficiently expands in the excavation hole to fill the looseness and gaps in the circumferential surface of the pile and increase the tip support force, circumferential frictional force, and pull-out resistance force.

To solve the above problems, the present invention of claim 1, the added cement flow animals a blowing agent having a pre-expansion agent in the borehole and Da設or infusion, the cement flow animals reverse tapered by foaming expansion, cement flow animals cured by expansion to occur the inflation pressure of the reverse tapered, as the cement flow animals, at least composed of cement, a cement milk, mortar, concrete, cement milk, mortar The foaming agent is added so that the expansion rate of concrete is 1% to 16% .

  In the present invention according to claim 2, as the foaming agent having an expanding action, at least an amphoteric metal powder such as aluminum powder and zinc, a carbon substance, and a peroxide substance that foams a gas by a chemical reaction in the cement composition , One or more selected from sulfonyl hydrazide compounds, azo compounds, nitroso compounds, and hydrazine derivatives.

According to the third aspect of the present invention, the amount of the aluminum powder added as the foaming agent, in which the drilling depth of the drilling hole is up to 150 m so that the expansion rate of the cement milk is 1% to 16%, 0.001% to 0.8% with respect to
The addition amount of the aluminum powder as the foaming agent that makes the drilling depth of the drilling hole up to 150 m so that the expansion rate of the mortar is 1% to 16% is 0.003% to 1.5% with respect to the cement mass. %
The amount of aluminum powder added as the foaming agent that makes the excavation depth of the drilling hole up to 150 m so that the expansion rate of the concrete is 1% to 16% is 0.004% to 5.2 with respect to the cement mass. %.

According to the fourth aspect of the present invention, the amount of aluminum powder added is calculated according to the water depth pressure and specific gravity at a predetermined depth in the excavation hole.

Cured according the present invention according to claim 1, the borehole foaming agent cement flow animals Da設or infusion supplemented with pre-expansion agent, the cement flow animals reversed tapered shape is foamed and expanded, it expands to since Suruse placement stream animal is place pile to rise to inflation pressure of the reverse tapered, by a simple method of adding a foaming agent having a large expansion agent, the tip bearing capacity and skin friction and pull-out resistance force You can build elevated cast-in-place piles.

In the present invention, by using the foaming agent, the Boyle's law is constructed under pressure, so that the cement fluid cast or injected into the drilling hole generates an inversely tapered expansion pressure.
That is, in the present invention, a cement fluid to which a foaming agent has been added is placed or injected under a pressure (hydraulic pressure) constrained by an excavation hole, and the cement fluid is expanded and expanded in a reverse taper shape. Since the volume of the cement fluid that hardens and hardens increases while generating an expansion pressure with an inverse taper-shaped expansion rate according to the depth of excavation, it is possible to build a cast-in-place pile that forms an inverse taper-shaped expansion.
The cement fluid to which the foaming agent is added generates an inverse taper-shaped expansion pressure within the range of the placement height to form an inverse taper-shaped expansion.
This reverse taper-shaped expansion consolidates and strengthens the looseness of the ground of the hole wall while pressing the hole wall of the excavation into the reverse taper shape with the expansion pressure.
In addition, foundation piles that have expanded to a reverse taper shape try to spread the consolidated and strengthened hole wall ground against the settlement of the loaded pile. It has the effect of resisting the pile and suppressing the settlement of the pile.
Further, in the range of the placement height, the cement fluid that expands and hardens forms an expanded wedge shape, and thus has an effect of greatly improving the resistance to drawing.
In addition, when steel reinforcements such as rebars and steel pipes are built in prefabricated piles (steel piles, prefabricated concrete piles), the cement fluid that expands and hardens, Since expansion pressure is simultaneously applied to steel reinforcements such as rebars and steel pipes, the expansion pressure of cement fluid that expands and hardens is constrained by the hole wall ground and ready-made piles or steel reinforcements such as rebars and steel pipes. At the same time, since the reaction force of the reaction is received, the cement fluid that expands and hardens, the hole wall ground, and the prefabricated pile, or the steel reinforcing material such as a reinforcing bar or steel pipe, can be integrated with a strong consolidation force. is there.
As described above, since the cement fluid to be cast or injected generates an expansion pressure having a reverse taper shape by a simple method of placing or injecting a cement fluid to which a foaming agent having an expansion action is added. The cast-in-place pile method has the effect of improving the tip support force, peripheral friction force and pulling resistance force.

Moreover, the present invention described in claim 1 does not need to provide a step of casting concrete and injecting cement milk after hardening like the tip preload cast-in-place pile method described in Patent Document 1. .
That is, the present invention adds a foaming agent having an expansion action to the cement fluid and integrally constructs the cast-in-place pile, so there is no need to perform multiple constructions as described in the above-mentioned patent document. It is only necessary to perform the construction.
Therefore, the cast-in-place pile method of the present invention has an effect of shortening the time until performance is exhibited.

Further, in the present invention according to claim 1, since a foaming agent having an expanding action is simultaneously added to the cement fluid to cause the cement fluid to foam and expand and harden, the above Patent Document 2 and Patent Document 3 As described, there is no need to harden the expansion material after hardening the portion of the foundation pile.
Therefore, the cast-in-place pile method of the present invention has an effect of shortening the time until performance is exhibited.
Furthermore, the cement fluid is at least cement milk, mortar, concrete made of cement, and the foaming agent is added so that the expansion rate of cement milk, mortar, concrete is 1% to 16%. The expansion rate of cement milk, mortar, concrete, etc. of the cement fluid that expands and hardens can occur from 1% to 16%.
The cement fluid having an expansion rate of 1% to 16% according to the present invention generates an expansion pressure having an expansion rate of 1% to 16%, so that the cement flow body that expands and hardens becomes a hole wall of a drilling hole. The ground is pressed with expansion pressure to strengthen the consolidation and has the effect of being firmly integrated with the hole wall ground.
Further, as the expansion pressure with an expansion rate of 1% to 16% increases, the cement fluid body that expands and hardens due to the action / reaction pressure becomes more firmly integrated with the hole wall ground.
When the expansion rate of the cement fluid to which the foaming agent is added is less than 1%, the expansion pressure becomes small, and the adhesion force of the compaction force between the cement fluid and the hole wall ground of the excavation hole becomes weak.
When the expansion rate of the cement fluid added with the foaming agent is larger than 16%, the expansion pressure increases, and the cement fluid body and the hole wall ground of the excavation hole have good adhesion, but the strength of the cement fluid body greatly decreases. End up.

In the present invention according to claim 2, as the foaming agent having an expanding action, at least an aluminum powder, an amphoteric metal powder such as zinc, a carbon substance, a peroxide substance, which foams a gas by a chemical reaction in the cement composition, Since one or more selected from a sulfonyl hydrazide compound, an azo compound, a nitroso compound, and a hydrazine derivative are added, the foaming agent has a gas buoyancy when foaming the gas by a chemical reaction in the cement composition. Is used to promote the diffusion of the cement and to fully develop the function of the foam expansion of the cement fluid to produce a dense and uniform expansion throughout the expanding cement fluid.
The foaming agent can be selected by adding the optimum type according to the properties, and the necessary expansion coefficient can be obtained by reliably foaming the gas.
For example, by selecting two types of foaming agents, it is possible to generate two types of gas having different bubble sizes in the cement fluid and generate a cement fluid that expands due to large and small bubbles.
The expansion of the cement fluid to which the foaming agent is added has an effect of pressing the loose ground and the looseness of the peripheral ground of the excavation hole by excavation with a large expansion pressure to consolidate and strengthen the ground.
In addition, due to the foam expansion pressure of the cement fluid, the expansion pressure of the action / reaction increases the peripheral frictional force by the adhesive force of the strong compaction force between the cement fluid that expands and hardens and the hole wall ground.
In addition, since the foaming agent diffuses the cement in a dense and uniform manner throughout the cement fluid, the expansion pressure of the cement fluid is generated uniformly, and the steel reinforcement such as prefabricated piles or reinforcing bars and steel pipes and the cement fluid Adhesion is improved by the expansion pressure.
As described above, the cement fluid to which the foaming agent is added expands and expands greatly, and therefore has an effect of greatly increasing the adhesion force by the compaction force of the expansion pressure as compared with the prior art.

In the present invention according to claims 3 and 4 , the additive amount of the aluminum powder as the foaming agent which makes the excavation depth of the excavation hole up to 150 m so that the expansion rate of the cement milk is 1% to 16% is Addition of aluminum powder as a foaming agent with a drilling depth of up to 150 m so that the expansion rate of the mortar is from 1% to 16% with respect to the mass from 0.001% to 0.8% As the foaming agent, the amount is 0.003% to 1.5% with respect to the cement mass, and the drilling depth of the drilling hole is up to 150 m so that the expansion rate of the concrete is 1% to 16%. When the addition amount of aluminum powder is 0.004% to 5.2% with respect to the cement mass, the expansion rate of these cement milk, mortar and concrete occurs from 1% to 16%. Door can be.
The expansion rates of cement milk, mortar, and concrete have a substantially linear correlation with the cement mass depending on the amount of aluminum powder added. It can adjust suitably with the addition amount of powder. If cement milk, mortar, and concrete require a large expansion coefficient, a predetermined expansion coefficient can be generated by predictably increasing the amount of aluminum powder added to the cement mass.
Moreover, the addition amount of said aluminum powder is computable according to the water depth pressure and specific gravity in the predetermined depth in an excavation hole.
Therefore, by setting the amount of aluminum powder added to the depth of excavation under high water pressure (pressurization) under the constraint of the excavation hole, cement milk, mortar, and concrete generate an expansion rate of normal pressure (atmospheric pressure). Therefore, the occurrence of the expansion coefficient of cement milk, mortar, and concrete is appropriately adjusted with the amount of aluminum powder added so that the depth of excavation is up to 150 m.
The expansion rate of cement milk added with aluminum powder is less than 0.001% of the addition amount of aluminum powder with respect to the cement mass, the expansion rate of mortar is less than 0.003% with respect to the cement mass, and the expansion rate of concrete is In the case of less than 0.004% with respect to the cement mass, the cement milk, mortar, which expands and hardens in the borehole, and the expansion rate of the concrete becomes less than 1%, and the cement milk, mortar, which hardens by expansion, While the decrease in the strength of concrete can be suppressed, sufficient expansion pressure cannot be applied to the hole wall ground of the excavation hole.
Also, the expansion rate of cement milk is more than 0.8% of aluminum powder added to the cement mass, the expansion rate of mortar is more than 1.5% of the cement mass, the expansion rate of concrete is the cement mass In contrast, when the content exceeds 5.2%, the expansion rate of cement milk, mortar, and concrete that expands and hardens in the excavation hole is larger than 16%, so that the adhesion strength of the consolidation force with the hole wall ground is increased. The decrease in strength of things increases. In order to increase the strength, it is necessary to increase the amount of cement, which increases the material cost and deteriorates the economy.
In this way, by setting the amount of aluminum powder added that can occur from 1% to 16% in the expansion rate of cement milk, mortar, and concrete, an expansion pressure having a predetermined expansion rate can be generated, and excavation can be performed. It has the effect of integrating with the hole wall ground of the hole by the adhesion of a strong compaction force.

It is explanatory drawing explaining the construction method of the standard cast-in-place concrete pile concerning a present Example. It is explanatory drawing explaining the construction method of the cast-in-place concrete pile different from FIG. It is explanatory drawing explaining the construction method of the cast-in-place concrete pile different from FIG.1 and FIG.2. It is explanatory drawing explaining the effect of the foaming agent etc. at the time of concrete hardening. It is explanatory drawing explaining the modification 1 of the construction method of a cast-in-place concrete pile. It is explanatory drawing explaining the modification 2 of the construction method of a cast-in-place concrete pile. It is explanatory drawing explaining the modification 3 of the construction method of a cast-in-place concrete pile. It is explanatory drawing explaining the modification 4 of the construction method of a cast-in-place concrete pile. It is explanatory drawing explaining the modification 5 of the construction method of a cast-in-place concrete pile. It is a graph showing the relationship between a foaming agent and cement milk. It is a graph showing the relationship between a foaming agent and mortar. It is a graph which shows transition of expansion amount. It is a graph which shows the relationship between the amount of aluminum addition, and the intensity | strength in the case of no restraint and the case of restraint. It is the list showing the material used for the compounding example 1. FIG. It is a table | surface showing the compounding quantity of the use material of the compounding example 1. FIG. It is the list | wrist showing the fresh test and expansion coefficient when AL (aluminum powder) addition amount in the compounding example 1 is changed. It is a graph which shows the relationship between the expansion coefficient of the compounding example 1, and elapsed time. It is a graph which shows the regression formula of AL addition amount and an expansion coefficient in the compounding example 1. It is the list showing the material used for the compounding example 2. FIG. It is a table | surface showing the compounding quantity of the use material of the compounding example 2. FIG. It is the list | wrist showing the fresh test and expansion coefficient when AL addition amount in the compounding example 2 was changed. It is a graph which shows the regression formula of AL addition amount and an expansion coefficient in the compounding example 2. It is the list showing the material used for the compounding example 3. FIG. It is a table | surface showing the compounding quantity of the use material of the compounding example 3. FIG. It is the list showing the result of the fresh test of concrete. It is the list | wrist showing the fresh test and expansion coefficient when AL addition amount in the compounding example 3 was changed. It is the list showing AL addition amount and the expansion coefficient measurement result. It is a graph which shows the relationship between the expansion coefficient of the compounding example 3, and elapsed time. It is a graph which shows the regression formula of AL addition amount and an expansion coefficient in the compounding example 3. It is the list showing the material used for the compounding examples 4 and 5. FIG. (A) Mixing conditions / test, (b) List of used mixers / mixing methods. It is a table | surface showing the compounding quantity of the use material of the compounding example 4. It is the list | wrist showing the fresh test and expansion coefficient when AL addition amount in the compounding example 4 was changed. It is a graph which shows the relationship between the expansion rate of compounding example 4, and elapsed time. It is a graph which shows the regression formula of AL addition amount and an expansion coefficient in the compounding example 4. It is the list showing the compounding quantity of the use material of the compounding example 5. It is the list showing the concrete test result when AL addition amount in the blending example 5 is changed. It is a graph which shows the relationship between the expansion rate of compounding example 5, and elapsed time. It is a graph which shows the regression formula of AL addition amount and the expansion coefficient in the compounding example 5. It is the list showing the compounding quantity (without AL) of the use material of the compounding example 4 and the compounding example 5. FIG. It is the list showing the concrete test result in compounding example 4 and compounding example 5. 6 is a graph showing the amount of bleeding (cm 3) per elapsed time in Formulation Example 4 and Formulation Example 5. It is a graph showing the relationship between the addition rate of aluminum powder and the expansion rate in blending examples A, B, C, 1 to 5. It is the graph showing the relationship between the addition rate of the aluminum powder in concrete example C, 3, 4, and 5 and concrete compressive strength. It is the graph showing the relationship between the initial expansion coefficient of the addition rate of 0% of the aluminum powder and the water cement ratio in the blending examples C and 1 to 5.

  In the present invention, a basic method of placing or injecting a cement fluid into an excavation hole formed in the ground, in which the cement fluid to which a foaming agent having an expansion action has been added in advance is injected or injected into the excavation hole. Then, the cement fluid is foamed and expanded in a reverse taper shape, and the cement fluid that expands and hardens generates an expansion pressure in the reverse taper shape.

  Examples of the foaming agent having an expanding action include at least an aluminum powder, an amphoteric metal powder such as zinc, a carbon substance, a peroxide substance, a sulfonyl hydrazide compound, an azo compound, and a nitroso compound. , One or more selected from hydrazine derivatives.

  The cement fluid is at least one of cement milk, mortar, and concrete made of cement, and the foaming agent is added so that the expansion rate of cement milk, mortar, and concrete is 1% to 16%.

The amount of aluminum powder added as the foaming agent that makes the excavation depth of the drilling hole up to 150 m so that the expansion rate of the cement milk is 1% to 16% is 0.001% to 0.005% with respect to the cement mass. 8%
Alternatively, the addition amount of the aluminum powder as the foaming agent that makes the drilling depth of the drilling hole up to 150 m so that the expansion rate of the mortar is 1% to 16% is 0.003% to 1. 5%
Alternatively, the addition amount of the aluminum powder as the foaming agent that makes the excavation depth of the drilling hole up to 150 m so that the expansion rate of the concrete is 1% to 16% is 0.004% to 5. 2%.

  The amount of aluminum powder added is calculated according to the water depth pressure and specific gravity at a predetermined depth in the excavation hole.

The present invention is based on the cast-in-place concrete pile method of the inventor's previous patent application (Japanese Patent Application No. 2015-002905).
In the invention of the previous application, a cast-in-place concrete pile construction method in which concrete is placed in an excavation hole formed in the ground to construct a concrete pile, and the expanding concrete to which a foaming agent having an expansion action is added is added to the excavation hole. Concrete is expanded and hardened by adding aluminum powder as a foaming agent to be added in an amount of 0.004% to 0.025% by mass with respect to the cement mass. The foundation pile that expands and hardens and the surrounding ground are firmly integrated by causing expansion at the drilling hole and applying expansion pressure to the hole wall ground and receiving reaction force from the hole wall ground. .

  However, in the concrete to which the aluminum powder of the foaming agent of the invention of the prior application is added, the expansion rate of the concrete with the addition amount of the aluminum powder at normal pressure (atmospheric pressure) is normal pressure under high water pressure where the depth of excavation is deep. Can not cause concrete expansion rate at.

Usually, in the cast-in-place pile method, a stable liquid (including water and muddy water) is stretched near the construction ground to protect the hole wall in the drilling hole where the depth of excavation is deep.
For example, when the depth of excavation by the earth drill method, the all casing method, the reverse method, the BH method, the underground continuous wall method, or the like becomes deep, water or muddy water is used as follows.
In the all-casing method, in the geological formation where boiling can occur, concrete is placed after excavating to a predetermined depth while filling the excavation hole with water and mud during excavation.
In addition, in the earth drill method, reverse method, BH method, underground continuous wall method, etc., natural mud water and artificial mud water (stabilizing liquid) are used to prevent the collapse of the borehole wall. Is usually extended to the construction ground, and excavation is carried out with muddy water, and concrete is placed after excavation to the planned depth.
Thus, when the excavation depth of the excavation hole is deep, since the excavation hole is filled with mud water, a considerable water pressure is applied to the bottom portion of the excavation hole, that is, the tip portion of the concrete pile.

  Under high water pressure under the restraint of drilling holes with deep drilling depth, cement powder (cement milk, mortar, concrete) added with aluminum powder of foaming agent cast or injected into the drilling hole, the aluminum powder is chemically mixed with cement. It reacts to foam fine hydrogen gas (gas), but the volume of hydrogen gas decreases proportionally as the drilling depth increases (Boile's law), so the expansion rate of hydrogen gas is proportional to the drilling depth. Get smaller.

  This is because the expansion rate of cement fluid to which aluminum powder as a foaming agent is added becomes smaller in proportion to the depth of excavation under pressure under the constraint of the excavation hole, and the expansion rate of cement fluid is proportional to the depth of excavation. The reverse taper-shaped expansion coefficient is generated, and the reverse taper-shaped expansion pressure is generated.

In the cast-in-place pile method with a deep excavation depth, GL-86m is constructed in Japan for high-rise buildings, and GL-105m is constructed outside of Japan. It is estimated to be about GL-150m.
Therefore, the addition amount of the aluminum powder of the foaming agent is determined so as to cause the same expansion rate as that of the normal pressure even under the high water pressure where the maximum excavation depth is GL-150 m.

  The water pressure at the depth of excavation is 1 atm of water pressure + 1 atm = 2 atm to push the water surface, 3 atm, 20 atm, 6 atm, and 100m at depth of 10m. 11 atm and 16 atm under a water depth of 150 m.

  In order to bring about the expansion rate of normal pressure (atmospheric pressure) under high water pressure, the water pressure is 2 at atmospheric pressure at a water depth of 10 m, so the amount of aluminum powder added at normal pressure is doubled. Thus, an expansion rate at normal pressure can be generated under high water pressure.

  Therefore, it is 3 times (3 atm) below 20 m, 6 times (6 atm) below 50 m, 11 times (11 atm) below 100 m, and 16 times (16 atm) below 150 m.

  The cast-in-place pile method usually has a deep cave depth, but the top of the cement fluid to be cast or poured is close to the construction ground, so the cement fluid (cement milk, mortar, Concrete).

  The pressure at the water depth is 2.3 times the water pressure when the density (specific gravity) of the maximum density of the cement fluid is 2.3 because the density of water is 1.0.

  Therefore, the addition amount of aluminum powder at the depth of excavation is 2 (atmospheric pressure at a depth of 10 m) × 2.3 (concrete specific gravity) = 4.6 times below the addition amount of atmospheric pressure (atmospheric pressure) at a depth of 10 m. 3 x 2.3 = 6.9 times under 20 m water depth, 6 x 2.3 = 13.8 times under 50 m water depth, 11 x 2.3 = 25.3 times under 100 m water depth, 16 under 150 m water depth X2.3 = 36.8 times the amount added.

For example, when the excavation depth (pile tip) is GL-50m and the top of the pile is GL ± 0m (pile length 50m), the amount of aluminum powder added is GL-50m. If the density of cement fluid is 2.3 (specific gravity of concrete), it will be 2.3 times.
Therefore, the amount of aluminum powder added is 6 × 2.3 = 13.8 times the amount added at normal pressure.

  Moreover, when the maximum excavation depth is GL-150 m, the amount of aluminum powder added is 16 (16 atmospheres) × 2.3 (concrete specific gravity) = 36.8, which is 36.8 times the amount added at normal pressure. .

  In the present invention, since the foaming agent is added so that the expansion rate of the cement fluid is 1% to 16%, the amount of aluminum powder to be added is determined.

  According to the expansibility demonstration test of adding aluminum powder as a foaming agent to cement fluid (cement milk, mortar, concrete), the amount of aluminum powder added to cause the expansion rate of cement fluid to be 1% to 16% However, it is 0.001% to 0.02% for cement milk, 0.003% to 0.04% for mortar, and 0.004% to 0.14% for concrete with respect to cement mass. .

  Therefore, the maximum addition amount of aluminum powder when the maximum excavation depth is up to 150 m is 0.02% × 36.8 times = 0.636% in cement milk, so the maximum addition amount is 0.8%. And the range of the addition amount is 0.001% to 0.8%.

  In mortar, 0.04% × 36.8 times = 1.472%, so the maximum addition amount is 1.5% and the range of addition amount is 0.003% to 1.5%.

  In concrete, since 0.14% × 36.8 times = 5.152%, the maximum addition amount is set to 5.2%, and the range of the addition amount is set to 0.004% to 5.2%.

  Therefore, under pressure to make the maximum excavation depth of the cast-in-place pile method up to GL-150 m, the amount of aluminum powder added is 0.001% to 0.8% with respect to the cement mass in the case of cement milk. In the case of mortar, 0.003% to 1.5% of the cement mass, and in the case of concrete, 0.004% to 5.2% of the cement mass. Rate can occur from 1% to 16%.

  That is, in the case where the excavation depth is deep, in order for the cement fluid to be cast or injected into the excavation hole to generate a set expansion rate of 1% to 16%, the water depth pressure and stability according to the predetermined excavation depth of the excavation hole are stable. Add the amount of aluminum powder calculated considering the specific gravity of the liquid and the specific gravity of cement milk, mortar and concrete.

A blowing agent is used to expand the cement fluid.
The foaming agent is not particularly limited as long as it is capable of foaming a gas by a chemical reaction.

  In the above construction method, aluminum powder as a foaming agent has been described as an example, but as other foaming agents, a substance that foams a gas by a chemical reaction in a cement composition, an amphoteric metal powder such as zinc, carbon It is one or more selected from substances, peroxides, sulfonyldolazide compounds, azo compounds, nitroso compounds, and hydrazine derivatives.

Specific examples of the gas foaming material include peroxidic materials such as percarbonate, persulfate, perborate, permanganate, and hydrogen peroxide.
Examples of the nitrogen gas foaming substance include sulfonyl hydrazide compounds, azo compounds, nitroso compounds, hydrazine derivatives, and the like. Specifically, p-toluenesulfonyl hydrazide, benzenesulfonyl hydrazide, azodicarbonamide, azobisisobutylnitrile, N, N ′ -Dinitropentamethylenetetramine, 4,4'-oxybis, hydrazinecarbonamide and the like. These various foaming agents may be mixed and added.

By using these foaming agents, due to the chemical reaction in the cement composition, when the gas is foamed, buoyancy is used to promote the diffusion of the cement, and a sufficient foaming function is generated in the cement fluid. In addition, the adhesive strength between the cement and the aggregate can be increased, and dense expansion and hardening can be exhibited over the entire cement flow body.
In addition, the foaming agent has a sufficient foaming and expansion effect with a single material, but a plurality of foaming agents may be used in combination.

Since the foaming agent can adjust the foaming amount of the gas, the expansion amount of the cement fluid can be adjusted by the foaming amount of the gas.
The foaming agent is usually used for reducing the weight of concrete, but in the present invention, it is used as having an expanding action.

  The aluminum powder used as a foaming agent is preferably scaly and has a purity of 99% or more and a fineness of 180 mesh or more and is coated with stearic acid. Usually, JISK 5906 (aluminum powder for paint) Type II standard sieve 88μ residue 2% or less It is preferable that the chemical reaction start time with the cement is appropriately adjusted.

  The expanding cement fluid is composed of a cement fluid composed of cement and a foaming agent, and the cement is usually portland cement, blast furnace cement or the like, and is not particularly limited.

  The cement fluid is cement milk, mortar, concrete, mud mortar, soil cement, or the like of cement fluid composed of cement, and is composed of cement and water, cement and water and aggregate, mud and earth and sand.

  Sand or gravel is used as the aggregate. For example, molten slag containing aluminum instead of sand, slag originating from metal production (iron slag, non-ferrous metal slag) or the like may be used.

  Further, the cement fluid may be a cement-based water glass suspension type, a solution-type grout, a cement-type plastic grout, or the like composed of an admixture or admixture in cement and water glass.

  Further, a synthetic resin can be used instead of the cement fluid, and there is no particular limitation.

  In addition, fly ash, blast furnace slag fine powder, silica fine powder, bentonite, expansion material, admixture, foaming agent, fiber substance, metal wire, and the like may be mixed in the cement fluid.

  Examples of the fiber material include steel fiber, binion fiber, carbon fiber, and wollastonite fiber. When the fiber material is used, the crack resistance, toughness, and strength of the cured cement fluid are improved. Can do.

Fly ash is a by-product ash that is composed of silica and alumina as main components and is produced when coal is burned in a thermal power plant.
Further, fly ash is used as an admixture or fly ash cement.
When high quality fly ash is used, the unit water volume is reduced, the workability is improved, the hydration heat value is lowered, the long-term strength and durability are increased, the water tightness is improved, the chemical resistance is improved, and the chemical resistance is improved. Effects such as improvement can be obtained.

Admixtures are water reducing agents, high performance water reducing agents, setting retarders, swelling materials, water retention agents, thickeners and the like.
The following effects can be obtained by adding the admixture to the cement fluid.
(1) Good fluidity and little decrease in fluidity over time.
(2) Less material separation.
(3) A moderate setting delay can be obtained.
(4) It has moderate expansibility and good adhesion to coarse aggregate.
(5) The required strength, durability, and water tightness can be obtained after hardening in the restraint (in the excavation hole).

The foaming agent can be used with an expanding material.
The expandable material has the effect of compensating for shrinkage due to hydration and drying after hardening of the cement fluid (shrinkage is made zero), so the volume of the expanded material is more than the initial shrinkage until the cement fluid is hardened by the foaming agent. By compensating the shrinkage of the cement fluid after hardening with the expansion material, it becomes possible to guarantee the shrinkage of the cement fluid over the entire period of use.

The expansion material is not particularly limited, but includes calcium, sulfo-aluminate minerals that hydrate with cement and water to produce ettringite (3CaO · Al ₂ O ₃ · 3CaSO ₄ · 32H ₂ O). , And those containing lime that expands by generating calcium hydroxide (Ca (OH) ₂ ).

Below, standard cast-in-place concrete pile construction methods for cast-in-place piles, cast-in-place concrete pile construction methods with widened sections, mixed cast-in-place concrete pile construction methods, variations 1 to 5 of cast-in-place concrete pile construction methods, and cast-in-place piles A modification of the construction method will be described.
Subsequently, cement flow animals inflated (cement milk, mortar, concrete) details the verification test, place concrete piles and micro piles, Grand c Doanka, the embodiments in PC-well is described.

(Standard cast-in-place concrete pile method)
Initially, the construction method of the standard cast-in-place concrete pile 10 of this invention is demonstrated.
FIG. 1 is an explanatory diagram for explaining a standard method of cast-in-place concrete piles.

First, as shown in FIG. 1A, excavation holes 11 having a deep excavation depth are formed in the underground A by excavating with an excavator.
The excavation is carried out by earth drill method, all-casing method, reverse method, underground continuous wall foundation method (including wall pile and wall foundation), BH method, etc., and cylindrical or square tube-shaped excavation hole 11 is underground Formed in A.
In addition, the inner wall surface N of the excavation hole 11 other than the tip widening part 14 and the midway widening part 15 mentioned later is formed in the same diameter shape by the earth drill construction method etc.

  As shown in FIG. 1B, the inner wall N of the drilling hole 11 is protected by injecting a drilling liquid stabilizing liquid (including bentonite-based stabilizing liquid, polymer-based stabilizing liquid, etc.) 16 into the drilling hole 11. .

Next, as shown in FIG. 1 (c), a rebar cage 13 having a mesh structure is built in the excavation hole 11.
The reinforcing bar 13 is arranged in a mesh shape with a predetermined interval depending on the length and diameter of the concrete pile 10.

Also, an expanding concrete 12 to be placed in the excavation hole 11 is prepared.
Concrete is composed of cement (for example, Portland cement), water, and aggregate (fine aggregate and / or coarse aggregate).
In addition, in this invention, the concrete 12 which expand | swells in a raw plant factory or the field is produced | generated, and this is driven, It is characterized by the above-mentioned.

The expanding concrete 12 is obtained by adding admixtures such as a foaming agent having an expanding action in which the reaction start time is appropriately adjusted in addition to cement, water, and aggregate.
Moreover, the addition amount of the aluminum powder capable of causing a predetermined expansion rate at a predetermined depth is calculated by the method described above in consideration of the water depth pressure according to the excavation depth, the specific gravity of the stabilizing liquid, and the specific gravity of the concrete.

  Since the concrete strength of the cast-in-place concrete pile 10 decreases when the expansion rate is increased, it is necessary to control the expansion rate so as to suppress the decrease in strength as much as possible. Since it can be predicted by confirming the formulation test, it can be controlled within an allowable range.

Next, as shown in FIG. 1 (d), the tremy tube 17 is suspended in the excavation hole 11 in which the reinforcing bar 13 is built in the excavation hole 11.
Next, a pump is connected to the head of the tremy tube 17 to remove slime (not shown) at the tip S of the excavation hole 11.
Thereafter, concrete 12 is placed in the excavation hole 11 from the mixer truck (not shown) through the treme tube 17.

And as shown in FIG.1 (e), the placement height is confirmed with a measuring tape (not shown), and the tremy tube 17 is pulled out upwards.
At this time, in order to prevent the stabilizing liquid 16 and the expanding concrete 12 from being mixed, the bottom portion of the tremy tube 17 is always buried in the expanding concrete 12.
Further, the stabilizing liquid 16 is pulled out while placing the expanding concrete 12.

A concrete pile 10 can be constructed by curing and hardening the placed concrete 12 as necessary.
Thus, the concrete pile 10 main body of the present invention can be built by placing the expanding concrete 12 to which the foaming agent or the like is added and curing the concrete.

As shown in FIG. 4, the concrete casing expands by the bubbles 19 diffusing into the concrete 12 that expands by adding a foaming agent or the like.
In this way, the concrete 12 that is expanded by the foaming agent is expanded, and a gap formed between the inner wall surface N of the excavation hole 11 and the outer wall surface G of the concrete pile 10 is filled and an expansion pressure is applied.

  In addition, the volume of the concrete pile 10 is increased by the expanding concrete 12, so that pressure from the outer wall surface G of the concrete pile 10 is applied to the inner wall surface N of the excavation hole 11. Thus, pressure is applied to the outer wall surface G of the concrete pile 10.

Further, the expanding concrete 12 forming the main body of the concrete pile 10 is placed on the inner wall surface N of the excavation hole 11 substituting the formwork, so that the inner wall surface N (hole wall ground) of the excavation hole 11 substituting the formwork is placed. This restrains the expansion of the concrete 12 that expands.
Thereby, the clearance gap between the outer wall surface G of the concrete pile 10 and the inner wall surface N of the excavation hole 11 is filled, and these are integrated, with an expansion pressure and reaction force being applied.
Therefore, the concrete pile 10 has a large tip support force, peripheral surface friction force, and pull-out resistance force.

  In addition, compressive stress is generated in the expanding concrete 12 itself, and in addition to this, if the reinforcing steel basket 13 is built, the concrete pile 10 main body is pre-stressed, that is, chemical prestress is also present. Thus, pile strength can be improved.

Further, in a raw plant factory or on-site, in addition to cement, water, aggregate, an admixture material such as a foaming agent having an expanding action is added to generate a concrete 12 that expands, and this is placed in the excavation hole 11. Therefore, the cast-in-place concrete pile 10 can be built with only one construction.
Therefore, the time until the performance of the concrete pile 10 can be shortened as compared with the prior art disclosed in the prior patent document.

  Thus, the construction method of the cast-in-place concrete pile 10 of this invention is a comparatively simple construction method, and can build a strong foundation pile.

  Finally, as shown in FIG. 1 (f), the casing is removed from the excavation hole 11, the empty moat is backfilled, and the cast-in-place pile construction is completed. A standard cast-in-place concrete pile 10 is completed.

(Cast-in-place concrete pile construction with widened section)
Next, a construction method in which the expanding concrete 12 to which the foaming agent is added is placed in the widened portion formed in the tip portion S of the excavation hole 11 or in the middle portion T of the excavation hole 11 will be described.

  FIG. 2 is an explanatory view for explaining a construction method for placing the expanding concrete 12 having an expanding action on the widened portion formed at the tip S or midway T of the excavation hole 11.

  A widening excavator (not shown) is used as a drilling method for forming a widened portion (tip widened portion 14 or midway widened portion 15) in which the distal end S or midway portion T of the excavation hole 11 is widened.

  That is, as a widening excavator (not shown) in the earth drill method, a bucket (not shown) that excavates the inside of the underground A and forms the excavation hole 11 has a flared shape. 11 may have a shape in which the tip portion S of the skirt extends.

Alternatively, an inclined surface widening blade (not shown) for excavating the upper inclined surface portion B of the distal end widening portion 14 is provided above the bucket, and this blade protrudes outward from the excavation range of the bucket, thereby making the distal end of the excavation hole 11 The portion S may form the tip widened portion 14 having a shape that spreads at the bottom.
In this widening excavator, after excavating the excavation hole 11 to a predetermined depth, the bucket is inserted into the excavation hole 11, and the slope part widening blade is opened to excavate the upper slope part B of the excavation hole 11 widened part, The rising portion widening blade is opened to widen the lower rising portion C of the excavation hole 11 for excavation.

As shown in FIG. 2A, the widening excavator forms a distal end widened portion 14 that is larger than the shaft portion at the distal end S of the excavation hole 11.
Then, the expanding concrete 12 having an expanding action is placed in the widening end portion 14 of the excavation hole 11.
Then, the expanding concrete is filled in the tip widened portion 14 of the excavation hole 11 while generating and expanding bubbles 19.

In this way, the expanding concrete 12 having an expanding action is placed on the distal end widening portion 14 and hardened, whereby the distal end S of the excavation hole 11 expands downward as shown in FIG. Force to act.
Further, a reaction force from the inner wall surface N of the tip S of the excavation hole 11 acts.
Thereby, the concrete pile 10 and the inner wall surface N are united with each other at the tip portion S, and the tip support force is increased.

Further, in the upper slope portion B of the excavation hole 11, an obliquely upward force from the concrete pile 10 to the excavation hole 11 acts.
Therefore, the circumferential frictional force is further increased by the generation of the obliquely upward force that does not act on the normal concrete 18. In addition, the pulling resistance is increased.

Next, in the middle portion T of the excavation hole 11, excavation is performed with a blade or the like (not shown) protruding outward from the bucket above the cylindrical bucket, so that the diameter is larger than the diameter of the excavation hole 11. A midway widened portion 15 is formed.
A plurality of midway widening portions 15 can be provided in the excavation hole 11.

And as shown in FIG.2 (b), the concrete 12 which expand | swells which has an expansion | swelling action in this middle part T is laid.
Then, the concrete 12 which expands in the midway widened portion 15 while being expanded by generating bubbles 19 is filled. In addition, the expansion action fills the concrete 12 that expands to the narrowest part of the outermost corner of the midway widened portion 15.

Thereby, as shown in FIG.2 (b), in the midway widening part 15 of the excavation hole 11, the diagonally upward and diagonally downward force acts toward the concrete pile 10 outward.
Further, a reaction force against this acts from the inner wall surface N of the excavation hole 11.
Accordingly, in the midway widened portion 15, a force that does not act on the normal concrete 18 is generated, so that the peripheral surface friction force and the pulling resistance force are further increased.

As described above, in the present embodiment, the concrete 12 that expands is placed in the middle by placing the concrete 12 that expands into the tip widened portion 14 at the tip S of the excavation hole 11 or the middle widened portion 15 at the midway T. Since it expands at the widened portion 15, the peripheral frictional force and the tip support force increase.
That is, it is possible to increase the volume of the expanding concrete 12 at the widened portion, increase the peripheral friction force generated there, and increase the peripheral support force and the pulling resistance force.

(Mixed cast-in-place concrete pile method)
In this embodiment, the concrete pile 10 is formed by mixing the expanding concrete 12 and the normal concrete 18 that does not expand.
FIG. 3 is an explanatory diagram for explaining the cast-in-place concrete pile 10 in which the expanding concrete 12 and the normal concrete 18 are mixed.

  First, a predetermined amount of expanding concrete 12 to which a foaming agent is added is placed on the tip side through the tremy pipe 17, and then a normal concrete 18 is placed on the pile head of the concrete pile 10.

  Thereby, as shown to Fig.3 (a), the concrete 12 layer which the concrete expand | swells in the lower part is formed, and the concrete pile 10 in which the normal concrete 18 layer was formed in the upper part can be built.

Thus, the concrete pile 10 in which the tip supporting force is increased by forming the expanding concrete 12 layer in the lower part can be constructed.
In particular, the concrete pile 10 having an increased tip supporting force can be constructed by forming a concrete 12 layer that expands in the lower part.

  In addition, as shown in FIG.3 (b), the concrete pile 10 formed in multiple layers can be formed by mixing the concrete 12 which expands, and the normal concrete 18. As shown in FIG. The number of layers is not limited.

Moreover, it has the effect that the concrete pile 10 can be constructed | assembled, adjusting the expansion rate by changing the addition amount of a foaming agent in each layer of the concrete 12 which expand | swells.
For example, it is possible to build a concrete pile 10 having a higher expansion coefficient in the lower concrete layer and a lower expansion coefficient in the upper part.

  In this way, by placing a plurality of layers of concrete 12 that expands into normal concrete 18 in a mixed manner, the tip support force, circumferential frictional force and pulling resistance force in the excavation hole 11 are increased according to the plurality of layers. It has an effect that can be done.

As mentioned above, although the embodiment of the cast-in-place concrete pile construction method of this invention was described based on drawing, other embodiment which gave various deformation | transformation and improvement based on the cast-in-place concrete pile construction method using the concrete which expand | swells is shown. It is also possible to implement.
In the following modification, it is the construction method of the composite pile of the cast-in-place concrete pile and the ready-made pile using the expanding concrete. In other words, the cast-in-place concrete pile method that casts concrete that expands into the direct pile, the tip widened pile and the mid-width widened pile of the cast-in-place concrete pile. The excavation is the earth drill method, the all casing method, the reverse method, the BH method, the deep foundation. A prefabricated pile is built on the upper part (pile head) of a cast-in-place concrete pile such as the construction method or continuous underground wall construction method (including wall piles and wall foundations), and the tip part (rooting part) and expansion of the ready-made pile It is also possible to implement the method of cast-in-place concrete composite piles, where the upper part is composed of ready-made piles and the lower part is expanded concrete piles.

(Modification 1 of cast-in-place concrete pile)
In the modified example 1, as shown in FIG. 5, the concrete 12 that is inflated into the rebar cage in the excavation hole, and the pre-made pile 20 is inserted into the concrete 12 that is inflated further, and is composed of the concrete pile 10 and the pre-made pile 20. The pile 21 is formed. In addition, as the ready-made pile 20 in FIG. 5, a steel construction pillar is used as an example.

  The stabilization liquid 16 is filled in the excavation hole 11 to protect the inner wall surface N of the excavation hole 11. Next, a rebar cage 13 having a mesh structure is built in the excavation hole 11.

A tremy tube 17 is suspended in the excavation hole 11 in which the reinforcing bar 13 is built in the excavation hole 11.
Next, a pump is connected to the head of the tremy tube 17 to remove slime (not shown) at the tip S of the excavation hole 11. Thereafter, a predetermined amount of expanding concrete 12 to which a foaming agent has been added is placed on the tip side from the mixer truck (not shown) through the treme tube 17.

  Thereafter, the ready-made pile 20 is inserted into the expanding concrete 12 before hardening, and the composite pile 21 composed of the concrete pile 10 and the ready-made pile 20 is constructed.

  Thus, the tip supporting force, the peripheral surface friction force, and the pulling resistance force are increased by forming the composite pile 21 in which the concrete pile 10 in which the concrete 12 that expands in the lower part is hardened and the ready-made pile 20 are formed. The synthetic pile 21 can be constructed.

(Modification 2 of cast-in-place concrete pile)
In the second modification, as shown in FIG. 6, the concrete 12 that is made of the concrete pile 10 and the ready-made pile 20 is formed by driving the concrete 12 that expands into the excavation hole 11 and inserting the ready-made pile 20 into the expanding concrete 12. Is formed. In addition, as the ready-made pile 20 in FIG. 6, a steel construction pillar is used as an example.

  The stabilization liquid 16 is filled in the excavation hole 11 to protect the inner wall surface N of the excavation hole 11.

  A tremy tube 17 is suspended in the excavation hole 11. Next, a pump is connected to the head of the tremy tube 17 to remove slime (not shown) at the tip S of the excavation hole 11. Thereafter, a predetermined amount of expanding concrete 12 to which a foaming agent has been added is placed on the tip side from the mixer truck (not shown) through the treme tube 17.

  Thereafter, the ready-made pile 20 is inserted into the expanding concrete 12 before hardening, and the composite pile 21 composed of the concrete pile 10 and the ready-made pile 20 is constructed.

  Thus, the tip supporting force, the peripheral surface friction force, and the pulling resistance force are increased by forming the composite pile 21 in which the concrete pile 10 in which the concrete 12 that expands in the lower part is hardened and the ready-made pile 20 are formed. The synthetic pile 21 can be constructed.

(Variation 3 of cast-in-place concrete pile method)
In the third modified example, as shown in FIG. 7, after the reinforcing bar 13 and the ready-made pile 20 are integrated and built in the excavation hole 11, the expanding concrete 12 that is expanded is driven, and the concrete pile 10 and the ready-made pile 20 are used. The synthetic pile 21 to be formed is formed. In addition, as the ready-made pile 20 in FIG. 7, a steel steel pipe is used as an example.

  The stabilization liquid 16 is filled in the excavation hole 11 to protect the inner wall surface N of the excavation hole 11. Next, the upper part of the rebar cage 13 having a mesh structure is inserted and fixed in the intermediate space of the ready-made pile 20 and integrated.

The ready-made pile 20 integrated with the reinforcing steel basket 13 is built in the excavation hole 11, and the tremy pipe 17 is suspended in the excavation hole 11 through the inner hole of the ready-made pile 20.
Next, a pump is connected to the head of the tremy tube 17 to remove slime (not shown) at the tip S of the excavation hole 11. Thereafter, a predetermined amount of expanding concrete 12 to which a foaming agent has been added is placed on the tip side from the mixer truck (not shown) through the treme tube 17.

  A composite pile 21 composed of the concrete pile 10 and the ready-made pile 20 is constructed. That is, the ready-made pile 20 and the rebar basket 13 are integrated, and the concrete 12 that expands with the form in which the upper part of the rebar basket 13 is inserted into the hollow of the ready-made pile 20 is cured to build the composite pile 21.

  In this way, the composite pile 21 in which the concrete pile 10 in which the expanded concrete 12 is hardened, the ready-made pile 20 and the reinforcing steel basket 13 are integrated is constructed in the lower portion, thereby increasing the tip support force, the peripheral friction force, and the pulling resistance force. The constructed synthetic pile 21 can be constructed. Thus, the composite pile 21 which a pile head can endure enough when a horizontal force is applied can be constructed by using the ready-made pile 20 of a steel pipe for the pile head.

(Modification 4 of cast-in-place concrete pile)
In the modified example 4, the difference between the synthetic pile method 3 in FIG. 7 and the synthetic pile method 4 in FIG. 8 described above is that only the integration method of the reinforcing bar 13 built in the excavation hole and the ready-made pile 20 is different. Is a form in which the upper part of the reinforcing bar 13 is overlapped and fixed on the outer periphery of the tip part (rooting part) of the ready-made pile 20, and the other configurations are the same, and the same reference numerals are attached and overlapping description is given. Omitted.

  As shown in FIG. 8, a composite pile 21 composed of a reinforcing bar 13, a ready-made pile 20 and a concrete pile 10 is constructed.

  In this way, the composite pile 21 in which the concrete pile 10 in which the concrete 12 expanding in the lower part is hardened, the ready-made pile 20 and the rebar cage 13 are integrated is constructed, so that the tip support force, the peripheral friction force, and the pulling resistance force are increased. The increased composite pile 21 can be constructed.

  In addition, in the modification of the cast-in-place concrete pile in FIGS. 5-8, it is also possible to implement each modification by the ready-made pile root consolidation method using the expanding concrete as the tip root consolidation of a ready-made pile.

(Variation 5 of cast-in-place concrete pile)
In the modified example 5, as shown in FIG. 9, the concrete pile 10 is driven into the upper part (pile head) of the reinforcing bar 13 in the excavation hole 11 by wrapping the ready-made pile 20 so as to be integrated and expanded. The synthetic pile 21 which consists of the rebar basket 13 with the pile 20 is formed.
In order to improve the bending strength of the pile, the composite pile 21 is a cast-in-place steel pipe concrete pile in which the pile head of the cast-in-place concrete pile using expanding concrete is reinforced with a steel pipe with protrusions, a striped steel pipe, or a bare steel pipe. Cast-in-place concrete pile reinforced with carbon fiber pipe.

  The stabilization liquid 16 is filled in the excavation hole 11 to protect the inner wall surface N of the excavation hole 11. Next, the steel bar 13 having a mesh structure is reinforced with a ready-made pile 20 such as a steel pipe or a carbon fiber pipe and is built in the excavation hole 11.

The ready-made pile 20 is integrated into the upper part of the reinforcing bar basket 13 and built in the excavation hole 11, and the tremy pipe 17 is suspended in the excavation hole 11.
Next, a pump is connected to the head of the tremy tube 17 to remove slime (not shown) at the tip S of the excavation hole 11. Thereafter, a predetermined amount of expanding concrete 12 to which a foaming agent has been added is placed on the tip side from the mixer truck (not shown) through the treme tube 17.

  A synthetic pile 21 composed of the concrete pile 10 and the rebar cage 13 with the ready-made pile 20 is constructed. That is, since the diameter of the ready-made pile 20 is larger than the diameter of the reinforcing bar 13, the expanding concrete 12 is hardened while the upper part of the reinforcing bar 13 is inserted into the hollow of the ready-made pile 20, and the composite pile 21 is built.

  As described above, the composite pile 21 in which the concrete pile 10 in which the expanding concrete 12 is hardened and the rebar cage 13 with the ready-made pile 20 is integrated is built, thereby increasing the tip support force, the peripheral friction force, and the pulling resistance force. The constructed synthetic pile 21 can be constructed. In this way, by using the ready-made pile 20 for the pile head, it is possible to build a synthetic pile that the pile head can sufficiently withstand when a horizontal force is applied.

  Moreover, you may comprise so that a coupling | bonding with a concrete pile may be increased by providing a protrusion or an unevenness | corrugation in the outer periphery or inner periphery of a ready-made pile.

  The above-mentioned ready-made pile 20 is a steel pile or a ready-made concrete pile. High Strength Concrete Piles), ST Pile (Step Tapered Piles), Nodal Piles, SC Pile (Steel Composite Concrete Piles), PRC Pile (Pretensioned & Reniforced Spun High Strength Concrete Piles), SL Pile (Slip Layer Compund Piles) ) Etc.

  Note that the expanding concrete may contain a fiber material. Examples of the fiber material include steel fiber, vinylon fiber, carbon fiber, and wollastonite fiber. Expanding concrete containing fiber material has the effect of improving crack resistance, toughness and strength.

  The shapes of the piles in FIGS. 5 to 9 described above are straight piles (straight piles) of cast-in-place concrete piles using expanding concrete. However, as shown in FIG. It may be in a form in which ordinary concrete is cast on the top. In addition, application to tip widening piles and midway widening piles of cast-in-place concrete piles using expanding concrete, and underground continuous wall piles including tip widening and midway widening (including wall piles and wall foundations) Is also possible.

(Modification of cast-in-place pile method)
The cast-in-place pile method of the present invention is a basic method for placing or injecting a cement fluid into an excavation hole formed in the ground, and the cement fluid in which a foaming agent having an expansion action is added to the excavation hole in advance. This is a method of constructing a foundation pile in which the cement fluid is foamed and expanded into a reverse taper shape and the cement fluid that expands and hardens generates an expansion pressure in the reverse taper shape. The construction method is to construct foundation piles and foundation bodies.

  Although not shown, micropile for building foundation piles, ground anchors for building anchor foundations, underground wall foundations and continuous wall foundations for building foundation piles for wall piles and wall foundations, bottoms These are foundation methods such as caisson foundations and steel pipe sheet pile foundations for building the foundations of foundations, and earthen reinforcement earthworks and grouting works for building foundations of reinforcement bodies.

  Since these foundation methods are methods of constructing foundation piles and foundations by pouring or injecting cement fluid into the excavation holes formed in the ground, cement fluid to which a foaming agent has been added in advance is applied. Since the cement fluid can be foamed and expanded in a reverse taper shape by installing or injecting, the cement fluid that expands and hardens under a pressure such as the hydraulic pressure in the drilling hole generates an expansion pressure in the reverse taper shape. Foundation piles and foundation bodies can be built.

[Verification test of expanding concrete]
Hereinafter, the verification test of the expanding cement fluid to which the aluminum powder of the foaming agent is added will be described in detail. In conducting the demonstration test, eight types of blending examples are prepared and each blending example is sequentially explained and considered.
[Composition Example A]
Formulation example A is cement milk blended with aluminum powder as a foaming agent and cement paste (water, ordinary Portland cement, high-performance AE water reducing agent standard form).
FIG. 10 is a graph showing the expansion rate when the amount of aluminum powder is changed and added to cement paste (water, normal Portland cement, high-performance AE water reducing agent standard form) as cement milk. Table 1 shows an example of blending cement paste and aluminum powder.

Ｊ１４ロート流下時間 ２５秒
・アルミニウム粉末（セルメックＰ）の添加量は表２に示す。

J2 funnel flow time 25 seconds. The amount of aluminum powder (Celmec P) added is shown in Table 2.

膨張率試験は、土木学会規準（ＪＳＣＥ−Ｆ ５２２）プレバックドコンクリートの注入モルタルの膨張率試験方法（ポリエチレン袋方法）によって測定した。

The expansion coefficient test was measured by the method of expansion coefficient test (polyethylene bag method) of injection mortar of the Japan Society of Civil Engineers (JSCE-F 522) pre-backed concrete.

That is, the graph shown in FIG. 10 shows the relationship between the amount of aluminum powder added as a foaming agent and the expansion rate of cement milk.
The expansion rate of the cement milk was shown by the addition amount of the aluminum powder of the foaming agent of 0 g / m ³ , 50 g / m ³ , 100 g / m ³ , 150 g / m ³ , and 200 g / m ³ .
The expansion coefficient in the range of the addition amount of aluminum powder from 100 g / m ³ to 200 g / m ³ can be obtained from a predictive approximate straight line indicated by a dotted line.

Since the expansion rate of cement milk has a correlation that increases substantially linearly with the increase in the amount of aluminum powder added to the cement mass, the amount of aluminum powder added in Table 2 is 0 g / m ³ , 50 g. In the case of / m ³ and 100 g / m ³ , the respective expansion coefficients are 0%, 5%, and 8%, so that the amount of aluminum powder added is 10 g / m ³ , 150 g / m ³ , and 200 g / m ³ . The expansion coefficient can be estimated as 1%, 12%, and 16% from a predictive approximate line, and the expansion coefficient can be appropriately adjusted by the amount of aluminum powder added.

Further, the addition amounts of aluminum powder of 50 g / m ³ and 100 g / m ³ are 0.8 g and 1.5 g, respectively, with respect to the cement mass (see Table 2). 10 g / m ³ , 150 g / m ³ , 200 g / m ³ are Table 2 and 10 g / m ³ are 0.155 g and 150 g / m ³ are 2.32 g at an addition rate of 0032% and 0.006%. 200 g / m ³ can be estimated to be 3.1 g, and the addition rates are about 0.00062%, about 0.0092%, and about 0.0124%.

  Therefore, the addition amount of aluminum powder that causes the expansion rate of cement milk to which the foaming agent is added to be 1% to 16% is about 0.00062% to about 0.0124% with respect to the cement mass.

[Composition Example B]
Formulation example B is a mortar in which aluminum powder as a foaming agent and mortar (cement + water + fine aggregate: sand, etc.) are blended. Table 3 shows the compounding materials. Table 4 shows the blending amounts of the blending materials. Table 5 shows the expansion rate of a mortar containing aluminum powder as a foaming agent as shown in Table 4.

膨張率試験は、土木学会規準（ＪＳＣＥ−Ｆ ５２２）プレバックドコンクリートの注入モルタルブリーディング率および膨張率試験方法（ポリエチレン袋方法）によって測定した。

The expansion rate test was measured by the Japan Society of Civil Engineers standard (JSCE-F 522) pre-backed concrete injection mortar bleeding rate and expansion rate test method (polyethylene bag method).

  That is, the graph shown in FIG. 11 shows the relationship with the expansion rate of the mortar depending on the addition rate of the aluminum powder of the foaming agent.

The expansion rate of mortar has a correlation that increases substantially linearly with the increase in the amount of aluminum powder added to the cement mass. Therefore, the amounts of aluminum powder added in Table 4 are 0 g / m ³ and 20 g / m. ³ and 40 g / m ³ , the respective expansion coefficients are 0%, 1.09% and 2.53%, and by drawing a predictive approximate line, the amount of aluminum powder added is 230 g / m ³ . In this case, it can be estimated that the expansion coefficient is 16.3%, and the expansion coefficient can be appropriately adjusted by adding the aluminum powder.

The addition amounts of aluminum powder of 20 g / m ³ , 40 g / m ³ , and 230 / m ³ are 0.003%, 0.006%, and 0.0337% with respect to the cement mass of 681 kg / m ³ , respectively. There than 11 1% and 16%, estimated to each ^{18g / m 3, 226g / m} 3, about 0.0026% addition of aluminum powder, respectively, it is about 0.0332%.

  Therefore, the addition amount of the aluminum powder causing the expansion rate of the mortar to which the blowing agent is added to be 1% to 16% is about 0.0026% to about 0.0332% with respect to the cement mass.

[Composition Example C]
Here, in the expansive concrete (slump blend) using ordinary Portland cement, the expansibility and restraint of concrete based on Table 6 (materials used table), Table 7 (concrete blend table), and Table 8 (concrete test results). A demonstration test of compressive strength was conducted in the case of none and in the case of restraint. FIG. 12 is a graph showing the transition of the aluminum powder addition rate and the expansion amount, and FIG. 13 is a graph showing the relationship between the aluminum addition amount on the horizontal axis and the strength on the vertical axis in the case of no restraint and in the case of restraint. It is.
The cement ratio when the added amount of aluminum powder is 0 g, 20 g, and 40 g with respect to the cement mass of 344 kg is calculated as 0%, 0.0058%, and 0.0116%. Moreover, each expansion coefficient according to the addition amount of aluminum powder will be -0.38%, 0.26%, and 1.58%. The water cement ratio is 45%.
As shown in Formulation Example C in FIG. 43, the expansion coefficient of the concrete to which aluminum powder is added increases approximately linearly according to the amount of aluminum powder added. Thus, the amount of aluminum powder added can be calculated by drawing an approximate straight line.
Therefore, when aluminum powder is added at an addition rate of 0.025%, the expansion rate of concrete can be predicted to be about 4.5% from a predictive approximate line. The addition rate is 0.030% and the expansion rate is 5.6%. Therefore, the expansion rate of concrete can be appropriately adjusted by the amount of aluminum powder added.
Considering the graph of FIG. 13, without restraint, the strength reduction decreases substantially linearly as the addition rate of aluminum powder increases, and the reduction strength rate when the addition rate of aluminum powder in the foaming agent is 0.0058%. When the addition rate of aluminum powder is 0.0116%, the reduction strength rate is 74.9%, and when the addition rate is 0.025%, the reduction strength rate is 45.36%. It can be predicted that the reduced strength rate is 33.78% at 0.030%.
Under restraint, when the addition rate of the aluminum powder is 0.0058%, the reduction strength rate is 94%, and when the addition rate of the aluminum powder is 0.0116%, the reduction strength rate is 94.98%. When the addition rate is 0.025%, it can be predicted that the reduced strength rate is 89.18% and the added strength rate is 0.030%, and the reduced strength rate is 86.87%.
From this graph, it is clear that the compressive strength is not significantly reduced under restraint.

・膨張は２時間程度で開始し、４から５時間程度で終了した（図１２参照）。
・供試体の拘束がない場合の強度低下は、膨張率１．５％程度で２５％低下した。
・供試体を拘束することで強度低下を抑えることが出来る。

Expansion started in about 2 hours and ended in about 4 to 5 hours (see FIG. 12).
-The decrease in strength when the specimen was not restrained was reduced by 25% at an expansion rate of about 1.5%.
-The strength reduction can be suppressed by restraining the specimen.

[Verification test of expanding concrete]
In the following, various demonstration tests of expansive concrete will be conducted, and the demonstration test of expansible concrete to which aluminum powder as a foaming agent is added will be described in detail. In conducting the demonstration test, five kinds of blending examples are prepared, and after discussing each blending example in order, consideration is given.

[Formulation Example 1]
FIG. 14 is a list showing materials used in Formulation Example 1, FIG. 15 shows the amount of materials used in Formulation Example 1, and FIG. 16 shows the amount of AL (aluminum powder) added in Formulation Example 1 varied. FIG. 17 is a graph showing the relationship between the expansion rate and the elapsed time in Formulation Example 1, and FIG. 18 is a regression of the AL addition amount and the expansion rate in Formulation Example 1. It is a graph which shows a type | formula.

  In Formulation Example 1, it is an expandable high-fluidity concrete using ordinary Portland cement. As shown in FIG. 16, the addition rate of aluminum powder as a foaming agent (cement mass ratio) 15 g, 30 g, and 45 g of aluminum powder with respect to 500 kg of cement are cement ratios of 0.003%, 0.006%,. It is calculated as 009%. Moreover, the expansion coefficient according to the amount of aluminum powder added is 0.2%, 1.0%, and 2.5%. The water cement ratio is 35%.

  As shown in FIG. 18, the expansion rate of the concrete to which aluminum powder is added increases substantially linearly according to the amount of aluminum powder added. Regression equation with rate y = 0.078X−1.0733 or an approximate straight line can be drawn in a predictive manner to calculate the amount of aluminum powder added.

  Therefore, as shown in Formulation Example 1 of FIG. 43, according to a regression equation, the expansion rate of concrete is about 3.6%, the addition rate is 0.015%, and the expansion rate is 0.012% when the addition rate of aluminum powder is 0.012%. About 4.77%, addition rate is 0.020, expansion rate is about 6.72%, addition rate is 0.025%, expansion rate is about 8.67%, addition rate is 0.030%, expansion rate is It can be calculated as about 10.62%, the addition rate of aluminum powder with an expansion rate of 1% of concrete is about 0.0053%, and the addition rate of aluminum powder with an expansion rate of 16% can be calculated as about 0.0437%. The amount of aluminum powder added causing an expansion ratio of 1% to 16% is about 0.0053% to about 0.0437% with respect to the cement mass.

  Therefore, since the expansion coefficient of concrete can be calculated from the addition amount of aluminum powder, the expansion coefficient of concrete can be set by appropriately adjusting the addition amount of aluminum powder.

[Formulation Example 2]
19 is a list showing materials used in Formulation Example 2, FIG. 20 shows the amount of materials used in Formulation Example 2, and FIG. 21 is a fresh test when the AL addition amount in Formulation Example 2 is changed. FIG. 22 is a graph showing a regression equation of the AL addition amount and the expansion coefficient in Formulation Example 2.

  In compounding example 2, it is an expandable high-fluidity concrete using blast furnace cement type B. As shown in FIG. 21, the addition rate of aluminum powder as a foaming agent (cement mass ratio) 0 g, 25 g, 37.5 g, and 50 g of the aluminum powder with respect to the cement amount of 407 kg are the cement ratios of 0%, 0.006%, It is calculated as 0.009% and 0.012%. Moreover, the expansion coefficient according to the addition amount of the aluminum powder is −0.3%, 0.5%, 1.35%, and 1.98%. The water cement ratio is 43%.

  As shown in FIG. 22, the expansion rate of concrete to which aluminum powder is added increases substantially linearly according to the amount of aluminum powder added. Regression equation with rate y = 0.0592X−0.9433 or an approximate straight line can be drawn to predict the amount of aluminum powder added.

  Therefore, as shown in Formulation Example 2 of FIG. 43, according to the regression equation, the addition rate of aluminum powder is 0.015%, the expansion rate of concrete is about 2.67%, the addition rate is 0.020%, and the expansion rate. Is about 3.87%, addition rate is 0.025%, expansion rate is about 5.08%, addition rate is 0.03%, expansion rate can be calculated as about 6.28%, concrete expansion rate is 1% The addition rate of aluminum powder is about 0.008%, the addition rate of aluminum powder with an expansion rate of 16% can be calculated to be about 0.0703%, and the expansion rate of concrete is 1% to 16%. The amount of aluminum powder added is 0.008% to 0.0703% with respect to the cement mass.

  Therefore, since the expansion coefficient of concrete can be calculated from the addition amount of aluminum powder, the expansion coefficient of concrete can be set by appropriately adjusting the addition amount of aluminum powder.

  In addition, since the expansion rate of the addition example 2 is 0% for the aluminum powder and the expansion rate for the concrete is -0.3%, the mixing rate is 0.3% + 6.28% at the addition rate 0.030% for the aluminum powder. = 6.58%.

[Composition Example 3]
FIG. 23 is a list showing materials used in the blending example 3, FIG. 24 is a list showing blending amounts of the materials used in the blending example 3, and FIG. 25 is a list showing the results of the fresh test of concrete. FIG. 27 is a list showing the fresh test and the expansion rate when the AL addition amount is changed in Formulation Example 3, FIG. 27 is a list showing the AL addition amount and the expansion coefficient measurement result, and FIG. 29 is a graph showing the relationship between the expansion rate and elapsed time, and FIG. 29 is a graph showing the regression formula of the AL addition amount and the expansion rate in Formulation Example 3.

  In Formulation Example 3, it is an expandable high-fluidity concrete using a low heat Portland cement. As shown in FIG. 26, the addition ratio of aluminum powder as a foaming agent (cement mass ratio) 20 g, 40 g, and 60 g of aluminum powder with respect to 500 kg of cement are cement ratios of 0.004%, 0.008%,. It is calculated as 012%. Moreover, the expansion coefficient according to the amount of aluminum powder added is 0.94%, 3.28%, and 4.67%. The water cement ratio is 34%.

  As shown in FIG. 29, the expansion rate of concrete to which aluminum powder is added increases substantially linearly according to the amount of aluminum powder added. Regression equation with rate y = 0.0935X−0.78 or an approximate straight line can be drawn in a predictive manner to calculate the amount of aluminum powder added.

  Therefore, as shown in Formulation Example 3 of FIG. 43, according to the regression equation, the addition rate of aluminum powder is 0.015%, the expansion rate of concrete is about 6.23%, and the expansion rate is 0.020%. Is approximately 8.57%, the addition rate is 0.025%, and the expansion rate can be calculated to be about 10.9%. The addition rate of aluminum powder with 1% concrete expansion rate is about 0.0038%, and the expansion rate The addition rate of 16% aluminum powder can be calculated to be about 0.0358%, and the addition amount of blowing agent aluminum powder that causes the expansion rate of concrete to be 1% to 16% is about 0.000% of the cement mass. From 0038% to about 0.0358%.

  Therefore, since the expansion coefficient of concrete can be calculated from the addition amount of aluminum powder, the expansion coefficient of concrete can be set by appropriately adjusting the addition amount of aluminum powder.

[Formulation Example 4]
FIG. 30 is a list showing materials used in Formulation Examples 4 and 5, FIG. 31 is a list showing (a) blending conditions and tests, (b) used mixers and mixing methods, and FIG. 32 is a blend. FIG. 33 is a list showing the blending amounts of the materials used in Example 4, FIG. 33 is a list showing the concrete test results when the AL addition amount in Blending Example 4 is changed, and FIG. 35 is a graph showing the relationship between the elapsed time and the elapsed time, and FIG.

  In compounding example 4, it is expansive concrete (slump compounding 18 cm) using ordinary Portland cement. As shown in FIG. 33, the addition ratio of aluminum powder as a foaming agent (cement mass ratio) 0 g, 30 g, 37 g and 44 g of the aluminum powder with respect to the amount of cement of 370 kg are the cement ratios of 0%, 0.008%,. It is calculated as 010% and 0.012%. Moreover, the expansion coefficient according to the addition amount of aluminum powder is −0.89%, −0.52%, −0.26%, and −0.02%. The water cement ratio is 50%.

  As shown in FIG. 35, the expansion rate of the concrete to which aluminum powder is added increases substantially linearly according to the amount of aluminum powder added. Regression equation with rate The amount of aluminum powder added can be calculated by drawing an approximate straight line y = 0.0357X-1.5881 or predictively.

  Therefore, as shown in Formulation Example 4 of FIG. 43, from the regression equation, the expansion rate of concrete is about 0.39% when the addition rate of aluminum powder is 0.015%, and the expansion rate when the addition rate is 0.020%. Is about 1.05%, the addition rate is 0.025%, the expansion rate is about 1.71%, the addition rate is 0.03%, and the expansion rate is about 2.37%. The expansion rate of concrete is 1 % Aluminum powder addition rate is about 0.0195%, and the expansion rate of 16% aluminum powder can be calculated to be about 0.1331%, and the expansion rate of concrete causes 1% to 16% foaming The amount of aluminum powder added to the agent is about 0.0195% to about 0.1331% with respect to the cement mass.

  Therefore, since the expansion coefficient of concrete can be calculated from the addition amount of aluminum powder, the expansion coefficient of concrete can be set by appropriately adjusting the addition amount of aluminum powder.

  Moreover, since the expansion rate of the compounding example 4 is 0% of the addition rate of aluminum powder and -0.89% of the expansion rate of concrete, 0.89% + 2.37% when the addition rate of aluminum powder is 0.030% = 3.26%.

[Formulation Example 5]
FIG. 36 is a list showing the blending amounts of the materials used in blending example 5, FIG. 37 is a list representing the concrete test results when the AL addition amount in blending example 5 is changed, and FIG. 38 is a blending example. 5 is a graph showing the relationship between the expansion rate of 5 and the elapsed time, and FIG. 39 is a graph showing a regression equation of the AL addition amount and the expansion rate in Formulation Example 5.

  In compounding example 5, it is expansive concrete (slump compounding 18 cm) using ordinary Portland cement. As shown in FIG. 37, the addition ratio of aluminum powder as a foaming agent (cement mass ratio) 0 g, 30 g, 37 g and 44 g of the aluminum powder with respect to the amount of cement of 370 kg are the cement ratios of 0%, 0.008%,. It is calculated as 010% and 0.012%. Moreover, the expansion coefficient according to the amount of aluminum powder added is −0.55%, 0.47%, 0.90%, and 1.25%. The water cement ratio is 45.9%.

  As shown in FIG. 39, the expansion rate of the concrete to which aluminum powder is added increases substantially linearly according to the amount of aluminum powder added. Regression equation with rate y = 0.0557X-1.1881 or an approximate straight line can be drawn in a predictive manner to calculate the amount of aluminum powder added.

Therefore, as shown in Formulation Example 5 of FIG. 43, from the regression equation, the addition rate of aluminum powder is 0.015%, the expansion rate of concrete is about 1.9%, and the expansion rate is 0.020%. Is about 2.93%, the addition rate is 0.025%, the expansion rate is about 3.96%, the addition rate is 0.030% and the expansion rate is about 4.99%, and the expansion rate of concrete is 1 % Aluminum powder addition rate is about 0.0106%, expansion rate of 16% aluminum powder addition rate can be calculated to be about 0.0834%, and the expansion rate of concrete causes 1% to 16% foaming The amount of aluminum powder added to the agent is about 0.0106% to about 0.0834% with respect to the cement mass.
Therefore, since the expansion coefficient of concrete can be calculated from the addition amount of aluminum powder, the expansion coefficient of concrete can be set by appropriately adjusting the addition amount of aluminum powder.

  In addition, the actual expansion rate of the blending example 5 is 0% for the addition rate of aluminum powder and −0.55% for the expansion rate of concrete. Therefore, when the addition rate of aluminum powder is 0.030%, 0.55% + 4.99% = 5.54%.

[Summary of Formulation Examples C, 1 to 5]
From the above-described demonstration tests of Formulation Examples 1 to 5, the expansion rate of the expanding concrete based on the addition rate of the aluminum powder of the foaming agent can be predicted in advance, and naturally the expansion rate of the concrete is the addition of the aluminum powder. The amount can be adjusted as appropriate.

In addition, in Formulation Example 1 and Formulation Example 3, when the addition rate of the aluminum powder of the foaming agent is 0%, the initial expansion rate is 0% as shown in FIGS. As shown in FIG. 15, the water cement ratio of Formulation Example 1 is 35%, and as shown in FIG. 24, the water cement ratio of Formulation Example 3 is 34%.
Therefore, from the blending examples 1 to 5, the water cement ratio to make the initial expansion coefficient 0% can be estimated from the relationship between the concrete initial expansion coefficient (when the addition ratio of aluminum powder is 0%) and the water cement ratio.

  Here, the relationship between the initial expansion coefficient of the aluminum powder addition rate of 0% and the water cement ratio is shown as a graph in FIG. In FIG. 45, NO1 indicates the relationship between the expansion rate of 0% and the water cement ratio of 35% in Formulation Example 1, and NO2 indicates the relationship between the expansion rate of -0.3% and the water cement ratio of 43% in Formulation Example 2. NO3 indicates the relationship between the expansion rate of 0% of the blending example 3 and the water cement ratio of 34%, and NO4 indicates the expansion coefficient of the blending example of -0.89% and the water cement ratio of 50%. NO5 indicates the relationship between the expansion coefficient of -0.55% in Formulation Example 5 and the water cement ratio of 45.9%.

As shown in FIG. 45, each plot of the initial expansion coefficient of the water cement ratio of the blending examples C, 2, 4, and 5 is connected with a straight line, and further, an approximate straight line drawn with a dotted line is connected to the expansion coefficient of 0%, whereby concrete It can be read predictably that the initial expansion rate (when the addition rate of aluminum powder is 0%) is about 39.5% of the water cement ratio.
As a result, for Formulation Examples C, 1 to 5, the water cement ratio was set to 39.5% or less, and then the aluminum powder as a foaming agent was added to make the concrete based on the initial expansion coefficient of 0%. The set expansion coefficient can be reliably generated.

Moreover, the bleeding test was implemented about the compounding examples 4 and 5. FIG.
FIG. 40 is a list showing the blending amounts (without AL) of the materials used in blending examples 4 and 5, and FIG. 41 is a list representing the concrete test results in blending examples 4 and 5. FIG. 42 is a graph showing the amount of bleeding (cm ³ ) per elapsed time in Formulation Example 4 and Formulation Example 5.

  In FIG. 40, NO1 is Formulation Example 4 using the admixture SV10L, and NO2 is Formulation Example 5 using the admixture SF500S. That is, as shown in FIG. 41, the formulation example 4 of NO1 has a bleeding rate of 3.57% when the admixture SV10L (AE water reducing agent standard form) C × 1.0%, and the formulation example 5 of NO2 When the agent SF500S (high performance AE water reducing agent) C × 0.8%, the bleeding rate is 1.24%.

  On the other hand, when the foaming agent aluminum powder (Celmec P) is added to the concrete blend using the AE water reducing agent of the admixture, the amount of sedimentation is canceled because of the large amount of the original sedimentation. The amount of expanded concrete is reduced.

  On the other hand, when the foaming agent aluminum powder (Celmec P) is added to the concrete blend using the high-performance AE water reducing agent of the admixture, the unit water amount can be reduced, so that the amount of sedimentation is reduced, and finally The concrete can be expanded by a predetermined amount.

  As shown in FIGS. 41 and 42, the amount of concrete settling increases as the amount of concrete bleeding increases. Therefore, when the sedimentation amount of concrete increases, the amount of expansion due to the aluminum powder (Celmec P) of the foaming agent decreases.

  Therefore, it is possible to generate an expansion coefficient from an initial expansion coefficient of 0 by appropriately determining the amount of admixture added such as a high performance AE water reducing agent so that the bleeding rate of the concrete becomes 0%. It becomes.

  Therefore, the expansion of concrete due to the amount of aluminum powder added as a foaming agent is determined as appropriate by determining the amount of aluminum powder required for the set expansion rate by adding 0% of the initial expansion rate to suppress bleeding from the water-cement ratio. It is preferable to do.

  In order to increase the expansion rate of concrete, a large expansion rate can be obtained by increasing the unit cement amount and increasing the amount of aluminum powder added as a foaming agent.

[Concrete compressive strength verification test according to the amount of AL added]
FIG. 44 is a graph showing the relationship between the aluminum powder addition rate and the concrete compressive strength in Formulation Examples C, 3, 4, and 5.
As shown in FIG. 44, in the blending examples 3, 5, and 4, as the addition rate of the aluminum powder as the foaming agent increases, the reduction of the compressive strength changes substantially linearly. When the aluminum powder addition rate is 0.008%, the reduction strength rate of Formulation Example 3 is 92.02%, the reduction strength rate of Formulation Example 5 is 93.29%, and the reduction strength rate of Formulation Example 4 is 93. 60%. Therefore, when the aluminum powder addition rate is 0.008%, the reduction strength rate can be predicted to be about 92% at maximum.

  Further, when the aluminum powder addition rate is 0.012%, the reduction strength rate of Formulation Example 3 is 80.67%, the reduction strength rate of Formulation Example 5 is 84.91%, and the reduction strength rate of Formulation Example 4 Is 88.24%. Therefore, when the aluminum powder addition rate is 0.012%, the reduction strength rate can be predicted to be about 80% at the maximum, and the blending plan of the amount of the aluminum powder added as the foaming agent can be made in advance.

  In addition, since the reduction in compressive strength transitions substantially linearly, when the aluminum powder addition rate is predicted to be 0.015%, the reduction strength rate of Formulation Example 3 is 79.36%, which is a reduction of Formulation Example 5. The strength rate is 81.19%, and the reduced strength rate of Formulation Example 4 can be estimated to be 85.15%. Therefore, when the aluminum powder addition rate is 0.015%, the reduction strength rate can be predicted to be about 79% at the maximum.

  In addition, when the aluminum powder addition rate is 0.020%, the reduction strength rate of Formulation Example 3 is 68.40%, the reduction strength rate of Formulation Example 5 is 75.04%, The reduced intensity rate can be estimated as 80.41%. Therefore, when the aluminum powder addition rate is 0.020%, the reduction strength rate can be predicted to be about 68% at the maximum.

  As shown in Formulation Examples 3, 4, and 5 in FIG. 44, when the addition rate of the aluminum powder is 0.025%, the reduction strength rate of Formulation Example 3 is 60.58%. The reduced strength rate is 68.9%, and the reduced strength rate of Formulation Example 4 can be estimated to be 75.25%.

  In addition, when the amount of aluminum powder added is 0.030% predictively, the concrete compressive strength and the reduced strength rate of blending examples 3, 5, and 4 can be estimated as follows.

That is, the strength of Formulation Example 3 is 34.8 N / mm ^{2 and} the reduction strength rate of Formulation Example 3 is 53.37%. Moreover, the intensity | strength of the compounding example 5 will be 34.0N / mm < ² >, and the reduction | decrease strength rate of the compounding example 5 will be 63.31%. The strength of Formulation Example 4 is 33.8 N / mm ² , and the reduced strength rate of Formulation Example 4 is 69.69%.

  Therefore, when the addition rate of the aluminum powder is 0.025%, the reduction strength rate can be predicted from the approximate straight line as about 60% at the maximum.

  Moreover, when the addition rate of aluminum powder is 0.030%, the reduction strength rate can be predicted from an approximate straight line with a maximum of about 53%.

  From this, when the aluminum powder addition rate is 0.008%, the reduction strength rate is about 92% at the maximum, and when 0.012%, the reduction strength rate is about 80% at the maximum, and the reduction strength rate is 0.015%. When the rate is about 79% at the maximum and 0.020%, the reduced strength rate is about 68% at the maximum. When the rate is 0.025%, the reduced strength rate is about 60% at the maximum. When the maximum value is about 53% and the addition rate of aluminum powder is increased by 0.005%, it can be estimated that the concrete strength decreases substantially linearly in the range of about 7% to 11%.

  Therefore, since the aluminum powder addition amount and the cement amount are in a correlation, the concrete compressive strength due to the aluminum powder addition amount can be predicted.

The demonstration test of combination example C with and without constraint (free expansion) will be described.
First, in the case where there is a restriction in the blending example C, when the aluminum powder addition rate is 0%, the concrete strength is 51.8 N / mm ² . When the aluminum powder addition rate is 0.0058%, the concrete strength is 48.7 N / mm ² and the strength reduction rate is 94.01%. When the aluminum powder addition rate is 0.0116%, the concrete strength is 49.2 N / mm ² and the strength reduction rate is 94.98%.
When the addition rate of aluminum powder is 0.025%, the strength reduction rate can be estimated to be 89.18% at a concrete strength of 46.2 N / mm ² . In the case of 030%, it can be estimated that the concrete strength is 45.0 N / mm ² and the strength reduction rate is 86.87%.

  From this strength relationship, since the concrete strength of 0.0116% with a large addition amount is slightly higher than 0.0058%, the concrete expansion due to gas generation is present in the formwork. As a result, it is considered that the adhesion between the aggregate and the cement is improved, and the strength is slightly increased accordingly.

  However, when the aluminum powder addition rate is 0.025%, the strength reduction rate can be estimated as 89.18%, and when the aluminum powder addition rate is 0.030%, the strength reduction rate can be estimated as 86.87%. From the result that this reduction in strength is leveling off, it is considered that the restrained state is much better than the other blending examples 3, 4, and 5 and can form the restrained state.

  This is because in the cast-in-place concrete pile construction method of the present invention, by placing the expanding concrete in a constrained state (in the excavation hole), the decrease in the strength of the concrete can be at least leveled, that is, it expands. Concrete can reduce strength reduction due to expansion.

  On the contrary, in the case where there is no restraint in the blending example C, the concrete strength is greatly lowered when the addition amount of the aluminum powder is increased.

The unrestricted strength reduction in the blending example C shows a substantially linear relationship, and when the addition rate of the aluminum powder is 0.0058%, the strength reduction rate is 89.76%. When the addition rate of the aluminum powder is 0.0116%, the strength reduction rate is 74.9%. Predictably, when the addition rate of aluminum powder is 0.025%, the strength reduction rate can be estimated to be 45.36%. Predictably, when the addition rate of aluminum powder is 0.030%, the strength reduction rate can be estimated to be 33.78%, and the strength can be estimated to greatly decrease to 17.5 N / mm ² .

  Furthermore, in the case where the addition rate of the aluminum powder is 0.030%, the restriction of the combination example C is compared with the restriction of the combination example C. The unrestricted strength reduction rate of 33.78% of the blending example C is 86.87% (33.78 ÷ 86.87 × 100 =) of the restraining strength reduction rate of the blending example C is about 1 / 2.5. Yes, the strength reduction rate of the blending example 4 of 69.69% (33.78 ÷ 69.69 × 100 =) is about ½. Therefore, although there is a large difference in compressive strength between unconstrained and constrained, since the expanding concrete is securely restrained by the wall surface of the excavation hole, it can form a good restraint state as well as the restraint of Compounding Example C. Further, it is possible to produce a concrete that expands with little strength reduction due to expansion.

  As a result, in the demonstration test of the cement fluid to which the aluminum powder of the foaming agent is added, the amount of the aluminum powder of the foaming agent that causes the expansion rate of the cement fluid of cement milk, mortar and concrete to be 1% to 16%. Is about 0.00062% to 0.0124% based on cement weight for cement milk and about 0.0026% to 0.0332% based on cement weight for mortar.

In the case of concrete, in the blending examples 1 to 5, the blending example 3 having a small addition rate and a large expansion rate is about 0.0038% to about 0.0358% with respect to the cement mass, and the addition rate is large. In Formulation Example 4 having a small value, the content is about 0.0195% to about 0.1331% with respect to the cement mass.
Therefore, in the case of concrete, it is about 0.0038% to about 0.1331% with respect to the cement mass.

  Further, since the expansion rate due to the addition rate of the aluminum powder has a characteristic that the reaction rate becomes slower and the expansion rate becomes smaller as the temperature becomes lower even at the same addition rate, the addition amount of the aluminum powder is set to 0. In the case of mortar, it is preferably 0.003% to 0.04%, and in the case of concrete, 0.004% to 0.14%.

Further, as shown in FIG. 43, there is a correlation in which the expansion rate of cement milk, mortar, and concrete cement fluid depending on the addition rate of aluminum powder increases substantially linearly as the addition rate of aluminum powder increases. The expansion rate of the cement fluid can be predicted from the addition rate of the aluminum powder.

  Further, as shown in FIG. 44, the strength of the cement fluid due to the addition rate of the aluminum powder has a correlation that decreases substantially linearly as the addition rate of the aluminum powder increases. The compressive strength of the fluid can be predicted.

  Therefore, the cement fluid can predict a predetermined expansion rate and strength by appropriately adjusting the amount of aluminum powder added while taking into account the required expansion rate and required strength. The expansion coefficient and strength can be confirmed by a blending test or test kneading.

  Hereinafter, embodiments will be described with cast-in-place concrete piles, micropile, ground anchor, and PC well.

Predict the embodiment with cast-in-place concrete piles.
(Example 1 of cast-in-place concrete piles)
For example, pile diameter φ2000mm (excavation hole), excavation depth GL-25m, pile length L = 25m (between the pile tip GL-25m and GL-15m is concrete added with aluminum powder, GL-15m to GL ± 0m ( The construction ground) will be carried out with large-diameter foundation piles (composite piles in which ordinary concrete will be placed).

  First, the tip portion 10m (10m between GL-25m and GL-15m) of a pile having a pile length of 25m is placed with expanding concrete. Subsequently, normal concrete is placed for 15 m from the upper end of the expanding concrete to the top of the pile head (15 m between GL-15 m and GL ± 0 m).

  The expansive concrete to be placed first is a concrete to which aluminum powder whose reaction start time with cement has been appropriately adjusted is added. The expansion rate of the example 3 is 4.67% (addition rate of aluminum powder is 0.012%). use.

  The addition rate of aluminum powder that causes this expansion rate of 4.67% at GL-15m is 2.5 times because the pressure at the digging depth GL-15m is 2.5 atm, and the specific gravity of concrete is 2. Multiply by 3

That is, since the addition rate of 0.012% × 2.5 × 2.3 = 0.069% and the cement mass is 500 kg / m ³ , the amount of aluminum powder added is 500 kg / m ³ × 0. 069% = 0.345 kg / m ³ = 345 g / m ³ .
Therefore, since this expanding concrete has a GL-15m and an expansion coefficient of 4.67%, the expansion coefficient at the GL-25m of the pile tip is 4.67% × 2.5 (GL- 15m atmospheric pressure) = 11.675%, and 11.675% ÷ 3.5 (GL-25m atmospheric pressure) ≈3.33%.

  The expansion rate is 4.67% when the excavation depth is GL-15m, the pile diameter φ2000mm is the size of φ2046mm, and the expansion rate of GL-25m is 3.33% when the pile diameter φ2000mm is the size of φ2033mm. It is the magnitude of the inflation pressure.

  When the ground of the excavation hole is normal or loose, the foundation pile that forms a pile length of 25 m with a pile diameter of φ2000 mm has a pile diameter of 15 m on the pile head side (ordinary concrete) within the pile length of 25 m. Then, at 10 m on the lower end side of the pile (expandable concrete), the pile diameter of the upper excavation depth GL-15 m is φ2000 mm to φ2046 mm, and the lower excavation depth GL-25 m The pile diameter of this part swells from φ2000 mm to φ2033 mm, causing an expansion pressure of 13 mm reverse taper to form an inversely tapered expansion.

  The foundation pile that forms expansion in this reverse taper shape tries to spread the side wall ground in the reverse taper shape when the foundation pile sinks due to loading, so the side wall ground expresses resistance to settlement and suppresses settlement. Supporting force is improved.

Further, since the loose ground is pressed and compacted by the expansion pressure of the concrete that expands the looseness of the ground due to excavation, the foundation pile and the peripheral ground are firmly integrated and the peripheral frictional force is improved.
Moreover, since it is an expanded wedge shape having a reverse taper shape of 13 mm with a height of 10 m, the wedge shape that is firmly integrated with the peripheral ground surface greatly improves the pulling resistance.
Therefore, the foundation pile which formed the reverse taper-shaped expansion | swelling improves a tip support force, a surrounding surface friction force, and a drawing-out resistance force.

When the hole wall ground of the excavation hole is hard, the pile diameter φ2000mm of the expansive concrete pile part of the foundation pile expands in the excavation hole, but because the ground is hard, the expansion is sufficiently constrained by the excavation hole wall Since the foundation pile that has been expanded and hardened does not swell and forms an insufficient expansion with the reverse taper-shaped expansion pressure generated, the remaining expansion pressure that restrains the expansion presses the wall of the drilling hole and reacts. By receiving the reaction force, the expansion pressure of the foundation pile and the reaction force of the reaction from the excavation ground have the effect of firmly integrating the foundation pile that expands and hardens with the hole wall ground.
Therefore, the foundation pile which produces the expansion pressure of the reverse taper shape and formed the expansion of the insufficient reverse taper shape improves the tip support force, the circumferential frictional force, and the pulling resistance force.

When the hole wall ground of the excavation hole is very hard (for example, a rock formation), the diameter of the foundation pile is about 2,000mm, but it will try to expand in the excavation hole. However, since the expanding concrete generates a total expansion pressure with a reverse taper shape, it is stronger than the hole wall ground due to the reaction force of the total expansion pressure restrained by the drilling hole wall. Integrate.
Therefore, the foundation pile in which the expansion is restrained and the total expansion pressure is generated improves the tip support force, the circumferential frictional force, and the pulling resistance force.

Moreover, in terms of compressive strength, since the addition rate of the aluminum powder of Formulation Example 3 in FIG. 44 is 0.012% to 52.6 N / mm ^2, it is a good strength of the concrete pile.

(Example 2 of cast-in-place concrete piles)
For example, a pile foundation with a small diameter of pile diameter φ800 mm, excavation depth GL-20 m, pile length 20 m (pile tip 10 m is expansive concrete pile + pile upper end 10 m is normal concrete pile = composite pile 20 m) is carried out.
Concrete mix is 370kg / m ³ of cement amount of blending example 5 close to the current cast-in-place concrete pile, slump is 18cm and expansion rate is 4.99% (addition rate of aluminum powder of blending example 5 of FIG. 43 is 0.030%) ) Concrete is used.

First, the amount of aluminum powder added is 0% at normal pressure (atmospheric pressure) so that the expansion rate of concrete cast at a digging depth GL-10 m is 4.99%. Therefore, the amount of aluminum powder added at the digging depth GL-10m is 0.030% × 2 (atmosphere of GL-10m) × 2.3 (concrete specific gravity) = 0.138% with respect to the cement mass. Therefore, the addition amount of the aluminum powder is the cement mass of 370 kg / m ³ × 0.138% =. 0.5106 kg / m ³ ≈510 g / m ³ .

  Further, from Boyle's law, the expansion rate at a depth of 20 m is 4.99% × 2 (atmospheric pressure at a depth GL−10 m) ÷ 3 (atmospheric pressure at a depth GL−20 m) = 3.32%.

  The expansion rate of concrete with an excavation depth of GL-10m is 4.99%, the pile diameter φ800mm is expanded to φ819mm, and the expansion rate of depth GL-20m is 3.32%, the pile diameter φ800mm is expanded to φ813mm. Is the size of

  Therefore, the foundation pile forming a pile length of 20 m with a pile diameter of φ800 mm is 10 m in height from the tip of the pile, and the pile diameter of the portion of the excavation depth GL-10 m at the upper end is φ800 mm to φ819 mm, and the lower end ( The pile diameter of the portion of the excavation depth GL-20m at the tip of the pile) is expanded from φ800mm to φ813mm, creating an inverse taper-shaped expansion pressure of reverse taper 6mm, or forming an inverse taper-shaped expansion, or It is a foundation pile which has formed an insufficient reverse taper-shaped expansion, or has generated an inverse taper-shaped expansion pressure.

Moreover, in concrete strength, it is 34 N / mm < ² > from the mixing examples 5 of FIG. 44, and is a favorable concrete pile strength.

Next, the embodiment is predicted by micropile.
(Micropile)
A micropile is a generic name for cast-in-place piles and embedded piles with a small diameter of about φ100 mm to φ300 mm.
A natural pile is drilled and steel reinforcements such as rebars and steel pipes are inserted, and a cement pile is injected to build a foundation pile.

  For example, it is carried out with a foundation pile having a pile diameter of 200 mm, an excavation depth of 15 m, and a pile length of 15 m (expandable cement milk on the pile tip side 10 m + normal cement milk = synthetic pile 15 m on the pile top end side 5 m).

  First, in order to expand cement milk to 12% at a position where the excavation depth is 5 m, the addition amount of aluminum powder that is generated in the same manner as the expansion rate of the cement milk to be injected is obtained.

  In order for the expanding cement milk to cause 12%, the addition rate of aluminum powder is 0.0092% from FIG. 11, so 0.0092% to cause the expansion rate to be 12% at the digging depth GL-5m. (Addition ratio of normal pressure) × 1.5 (1.5 atm at a depth of 5 m) × 1.92 (cement milk specific gravity of 30% water cement ratio) ≈0.0264% of the added amount of aluminum powder.

Further, according to Boyle's law, the expansion rate at the depth of 15 m is 12% × 1.5 (atmospheric pressure at a depth of 5 m) ÷ 2.5 (atmospheric pressure at a depth of 15 m) = 7.2%.
This expansion rate is the magnitude of the expansion pressure at which the pile diameter φ200 mm expands to φ211 mm at the excavation depth GL-5 m, and the pile diameter φ200 mm of the depth GL-15 m (pile tip) expands to φ207 mm.

  Therefore, the foundation pile that forms a pile length of 15 m with a pile diameter of φ200 mm is 10 m in height from the tip of the pile, the pile head side of the pile length of 15 m forms a pile diameter of φ200 mm, and the pile tip side (lower side) of 10 m The upper end (excavation depth GL-5m) has a pile diameter of φ200mm and the lower end (pile tip) expands to a pile diameter of φ200mm and a diameter of φ207mm. In addition, the foundation pile has formed an inverse taper-shaped expansion, an insufficient reverse taper-shaped expansion, or an inverse taper-shaped expansion pressure.

Subsequently, the embodiment is predicted by a ground anchor.
(Ground anchor)
This is a foundation method in which cement fluid is injected into a drilling hole excavated in the ground, and an embodiment is predicted with a ground anchor for constructing a foundation body (anchor body).

The ground anchor is an anchor body (basic body) by inserting PC steel into a drilling hole drilled with water in a casing with a hole diameter of φ50mm to φ165mm and inserting cement fluid (cement milk, mortar, etc.). Is a basic construction method that stabilizes slopes, earth retaining walls, and structures by building a strong and stable ground.
Since this stable ground is a strong ground such as a rock formation or a formation close to a rock, an anchor body built in the stable ground can be expected to have a peripheral frictional force with an expansion pressure with a small expansion rate.
The expansion rate at which water becomes ice is about 9%, and this expansion rate is an expansion pressure that bursts the tubular tube under the restraint of the tubular tube such as a water pipe. Since the anchor body is also constrained in a strong stable ground, the expansion rate of the cement fluid to be injected is 5%.

  For example, an anchor body having a drilling diameter of 90 mm, a drilling depth of GL-25 m, and a fixing length of 7 m (injecting cement milk with aluminum powder added to the tip side 5 m into a strong stable ground + normal cement milk to the upper 2 m (Injection = 7 m synthetic anchor body)

First, the amount of aluminum powder added to build an anchor body having a 5% expansion rate of cement milk under a high water pressure with a drilling depth of GL-20 m is determined.
In order to produce 5% of cement milk, it can be seen from FIG. 10 that the rate of addition of aluminum powder is 0.0032% / m ³ with respect to the cement mass, so that an expansion rate of 5% occurs at a depth of GL-20 m. Is 0.0032% × 3 (atmospheric pressure at depth GL-20 m) × 1.92 (cement milk specific gravity at 30% water cement ratio) = 0.0096% / m ³ addition amount of aluminum powder addition rate It is.

Further, the expansion rate of the drilling depth GL-25m is 5% × 3 (atmosphere of depth GL-20m) ÷ 3.5 (atmosphere of depth GL-25m) ≈4.285% according to Boyle's law. It is.
Therefore, the anchor body has a depth of GL-20m and an expansion rate of 5% is φ90mm to φ92.2mm, and at a depth of GL-25m, the expansion rate is 4.285% and φ90mm to φ91.9mm. Occur.

The anchor body fixing length of 7 m is that the anchor body has a drilling diameter of 90 mm, and the anchor body has a hole diameter of 2 m from the drilling depth GL-18 m to GL-20 m. The diameter is φ90 mm, and between 5 m of drilling depth GL-20 m to GL-25 m, the expanded cement milk anchor body is GL-20 m, φ90 mm is φ92.2 mm, GL-25 m and φ90 mm is φ91.9 mm Inverse taper of bulges into a shape with a size of 0.3 mm, causing an expansion pressure.
Since this expanding anchor body is built in a strong stable ground (such as a rock formation or a formation close to a rock), a reverse taper-shaped expansion pressure is generated in the drilling hole in the stable ground, but the expansion is reduced. It does not swell and is restrained by the hole wall ground, and it is in a state where it receives the reaction force of the total expansion pressure by the reaction while generating the inverse taper-shaped expansion pressure, and applies the reverse taper-shaped expansion pressure to each other to apply the anchor body and the drilling hole. The ground is an anchor body that is integrated with a strong cohesive force.

Subsequently, the embodiment is predicted in the PC well.
(PC well method)
The PC well method is one of the caisson foundations and one of the open caisson press-fitting methods.
This method is a method in which a cylindrical single block is drilled with a hammer grab etc. while prestressing is introduced with a post-tension method, and a ground anchor or the like is used as a reaction force to press-fit and sink to a predetermined depth. This is a construction method in which an underwater inseparable concrete is placed on the bottom plate using the tremy method to construct the foundation of the bottom plate concrete.

  For example, under water pressure with a PC well outer diameter of 3,000 mm and an inner diameter of 2400 mm and a digging depth of GL-20 m, underwater concrete is cast to a digging depth of GL-17 m to construct a 3 m thick bottom base concrete foundation.

  The underwater concrete to be cast is an underwater inseparable concrete to which an underwater inseparable admixture is added, and uses an expansion coefficient of 3.28% (addition ratio of aluminum powder of 0.008%) in the blending example 3.

Under the water pressure of digging depth GL-20m, the addition rate of aluminum powder that causes this expansion rate of 3.28% is 0.008% × 3 (atmosphere of GL-20m) × 2.3 (concrete specific gravity) = It is 0.0552%, and the addition amount is a cement mass of 500 kg / m ³ × 0.0552% = 0.276 = 276 g / m ³ .

  Also, according to Boyle's law, the expansion rate at the digging depth GL-20m is 3.28%, so the expansion rate at the digging depth GL-17m is 3.28% × 3 (GL-20m atmospheric pressure) / 2. .7 (atmospheric pressure of GL-17m) ≈3.64%.

  The expansion rate at the top edge of the bottom base concrete with the excavation depth GL-17m is 3.64%, which is the magnitude of the expansion pressure that expands φ2400mm to φ2443mm, and the expansion at the lower end of the bottom base concrete with the excavation depth GL-20m The rate is 3.28%, which is the magnitude of the expansion pressure that expands φ2400 mm to φ2439 mm.

  Therefore, the foundation of the bottom concrete is 3 m in height (thickness), and the bottom base concrete of φ2400 mm swells to a size of a reverse taper of 4 mm with an upper part of φ2443 mm and a lower part of φ2439 mm. .

Further, the strength of this bottom base concrete is good at 60 N / mm ² from Formulation Example 3 in FIG.

  In this method, the cast concrete is poured into the bottom wall under pressure in the excavation hole and cemented fluid is added to the underwater concrete. Since the pressure is applied, the expansion of the inner wall surface of the PC well is restrained to generate a reaction force of the expansion pressure, and the PC well and the bottom concrete are firmly integrated with each other.

  In addition, concrete added with foaming agent placed on the bottom applies expansion pressure to the ground in the PC well tip, and the looseness of the ground due to excavation of the tip is pressed with the expansion pressure to consolidate the tip. As a result, the initial settlement of the PC well is suppressed and the tip supporting force is improved, and the inner wall surface of the PC well has a large water stop effect because the bottom base concrete is firmly integrated with the inverse taper-shaped expansion pressure.

  Thus, the caisson foundation for underwater excavation in the caisson includes a PC well method, a hyac press-in caisson method, an automated open caisson method (SOCS), an urban ring method, and the like. The steel pipe sheet pile foundation that excavates the steel pipe sheet pile underwater and constructs the foundation of the bottom base concrete is the same method.

As described above, the embodiment has been described with the cast-in-place concrete pile, the micropile, the ground anchor, and the PC well. However, when the ground of the excavation hole is normal or loose, the loosening of the ground due to excavation becomes large. Increase the expansion rate of cement fluid, press the loose drilling hole wall with expansion pressure and strengthen the consolidation, and apply the pressure of action and reaction to expand and harden foundation pile and foundation body and peripheral ground Can be firmly integrated.
Also, if the hole wall ground of the excavation hole is hard or very hard, the ground loosening due to excavation is small or not loose, so even if the expansion rate of the cement fluid to be cast or injected is reduced, it will loosen. The foundation pile and the foundation body and the peripheral ground are more firmly integrated by the adhesion force of the action-reaction compaction force that presses the ground with small or no looseness with the reverse taper-shaped expansion pressure.

  In the large-diameter caisson-based PC well, the expansion ratio of the PC well inner diameter φ2400 mm (outer diameter φ3000 mm) is expanded from φ2400 mm to φ2410 mm is 0.84%, and the expansion ratio is expanded from φ2400 mm to φ2420 mm. Yes, the expansion coefficient swells from φ2400 mm to φ2430 mm is 2.51%.

The large diameter cast-in-place concrete pile expands from φ2000mm to φ2010mm, the expansion rate is 1%, the expansion rate expands from φ2000mm to φ2020mm is 2%, and the expansion rate expands from φ2000mm to φ2030mm is 3%. is there.
As described above, in a large-diameter excavation hole, it is possible to generate an inverse taper-shaped expansion pressure that expands from about 10 mm to about 30 mm with a small expansion rate of 1% to 3%.

In addition, the small-diameter cast-in-place concrete piles expand from φ800 mm to φ810 mm, the expansion rate is 2.51%, the expansion rate from φ800 mm to φ820 mm is 20 mm, the expansion rate is 5.06%, and the expansion rate is from φ800 mm to φ830 mm, 30 mm. The expansion coefficient is 8.65%.
As described above, in a small-diameter excavation hole, it is possible to generate an inverse taper-shaped expansion pressure that expands from about 10 mm to about 30 mm with an expansion rate of 2% to 9%.

Further, the micropile with a small diameter expands the pile diameter φ200 mm to φ205 mm, the expansion coefficient is 5.06%, the expansion coefficient that expands φ200 mm to φ210 mm is 10.2%, and the expansion coefficient that expands φ200 mm to φ215 mm is 15.56. %.
In this way, in an excavation hole with a smaller diameter, an inverse taper-shaped expansion pressure that swells from 5 mm to 15 mm with an expansion rate of 5% to 16% can be generated.

In addition, since the anchor body is built in a stable ground (such as a rock formation or a formation close to a rock), a small-diameter ground anchor has a large expansion restraint. A peripheral friction force can be expected with an expansion pressure of a small expansion amount of about 1 mm to 4 mm.
The expansion rate is about 9%, the expansion rate is about 6.8%, the expansion rate is about 6.8%, the expansion rate is about 4.5%, and the expansion rate is about 4.5%. The expansion rate of swelling to 91 mm is about 2.2%.
As described above, the ground anchor can be expected to have a peripheral frictional resistance even if the expansion rate of the cement fluid is small.

As described above, some of the embodiments of the present invention have been described in detail with reference to the drawings. In these embodiments, a cement fluid to which a foaming agent has been added in advance is placed or injected into a drilling hole formed in the ground. Since it is a foundation construction method, it can be carried out by a foundation construction method in which a cement fluid to which a foaming agent has been added in advance is poured into an excavation hole formed in the ground and mixed with excavation soil to form a soil cement.
For example, there are a ready-made pile embedding method, a steel pipe soil cement pile method, a rotary pile consolidation method, a solidification method for ground improvement (a shallow layer mixed method, a middle layer mixed method, a deep layer mixed method), and a natural ground reinforced earth method.
These are methods of injecting cement fluid with foaming agent added into the excavated hole in the ground and mixing it with the excavated soil to form a soil cement. A foundation pile, a foundation body, an improved body, a reinforcing body, etc. can be created in which a soil cement which is expanded by foaming and expanded and hardened causes an inversely tapered expansion pressure.
In addition, the present invention can be implemented in other forms in which various modifications and improvements are made based on the knowledge of those skilled in the art, including the aspects described in the disclosure section of the present invention.

DESCRIPTION OF SYMBOLS 10 Cast-in-place concrete pile 11 Excavation hole 12 Expanding concrete 13 Reinforcing bar cage 14 Tip widening part 15 Middle widening part 16 Stabilizing liquid 17 Tremy pipe 18 Normal concrete 19 Bubble 20 Ready-made pile 21 Composite pile A Ground B Upper slope part C Lower part Rising part G Outer wall N Inner wall S Tip T T Midway

Claims (4)

It is a foundation method for placing or injecting cement fluid into an excavation hole formed in the ground,
The borehole of the blowing agent cement flow animals Da設or infusion supplemented with pre-expansion agent, the cement flow animals reversed tapered shape is foamed and expanded, cement flow animals cured by expansion of reverse tapered Causing expansion pressure ,
Moreover, the cement fluid is at least cement milk, mortar, and concrete made of cement, and the foaming agent is added so that the expansion rate of cement milk, mortar, and concrete is 1% to 16%. A cast-in-place pile construction method. Examples of the foaming agent having an expanding action include at least an aluminum powder, an amphoteric metal powder such as zinc, a carbon substance, a peroxide substance, a sulfonyl hydrazide compound, an azo compound, and a nitroso compound. The cast-in-place pile method according to claim 1, wherein the cast-in-place pile method is one or more selected from hydrazine derivatives. The amount of aluminum powder added as the foaming agent that makes the excavation depth of the drilling hole up to 150 m so that the expansion rate of the cement milk is 1% to 16% is 0.001% to 0.005% with respect to the cement mass. 8%
The addition amount of the aluminum powder as the foaming agent that makes the drilling depth of the drilling hole up to 150 m so that the expansion rate of the mortar is 1% to 16% is 0.003% to 1.5% with respect to the cement mass. %
The amount of aluminum powder added as the foaming agent that makes the excavation depth of the drilling hole up to 150 m so that the expansion rate of the concrete is 1% to 16% is 0.004% to 5.2 with respect to the cement mass. %
The cast-in-place pile method according to claim 1 or 2 , characterized in that: The cast-in-place pile method according to claim 3, wherein the amount of aluminum powder added is calculated according to a water depth pressure and specific gravity at a predetermined depth in the excavation hole .

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