JPH0452327A - Stabilized soil and construction method using this soil - Google Patents

Abstract

PURPOSE:To obtain high fluidity in filling and uniform strength as much as manifested in natural ground after solidification by mixing viscous soil containing a specific percentage of specific-size fine grains with water and solidifying agent added thereto. CONSTITUTION:Japanese Kanto loam 1 for which fine grains of size less than 75mum as viscous soil is specially 40wt.% or more of soil grains is mixed with water 2 by high-speed rotation soil mixer 3 into a muddy condition. Next, muddy water obtained in adjustment is transfered to a mixer 4, in which a preset amount of solidifying agent 5 is input for mixing. Stably treated soil A obtained in the mixer 4 is mixed with a preset amount of creamy bubble which is bubbled by a bubbling machine 6 to manufacture lighter stabilized soil B. The lighter stabilized soil B obtained in this way is forcibly filled into the under-footing pile head cavity portion and the under-floor portion 9 of a multiple dwelling house 8 via a pump 7.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is a method of stirring and mixing water and a cement-based solidifying agent into the viscous soil, which is difficult to reuse, in the residual soil generated from excavation work, etc. The present invention relates to the stably treated soil obtained and a construction method in which the stably treated soil is applied to backfilling, cavity filling, embankment, etc.

[Prior art and its problems] Generally, in backfilling methods, there are only a few cases where excavated soil can be used as is as a backfilling material. In other words, excavated soil that can be used as is is limited to some high-quality sandy soils. on the other hand,
In most other cases, construction methods are used in which mountain sand is brought in as backfill material in place of excavated soil, and this is compacted and used.

However, this construction method using mountain sand has the following disadvantages.

(a) Although it is inexpensive as a material, it has poor workability because it requires manual input and compaction (and it also has a large effect on the compaction state and the quality of the product, which may lead to large variations in quality). Become.

(b) It is difficult to reliably and uniformly fill details around buried pipes and piles, and even if final tightening is possible, voids tend to remain in the upper part of the cavity due to breathing.

(c) The better the compaction, the higher the bulk specific gravity. Therefore, when applied to cavity filling or embankment on soft ground, the weight of the sand itself will promote new settlement.

(d) The hardness and softness of the base ground affects the degree of compaction of sand.

(e) It is almost impossible to apply it to detailed underground cavity filling or vibrator filling.

(f) If the compaction is insufficient or gradually compacted due to traffic loads, vibrations such as earthquakes, or the action of groundwater, not only will the intended filling purpose not be achieved, but the pavement surface will become uneven due to the formation of underground cavities. In extreme cases, it can cause road depressions.

Apart from this construction method using mountain sand, it is also possible to make mortar fluid and make it suitable as a filler, and use this instead of mountain sand.In that case, the separation of materials would be large. The strength is comparable to that of a natural rock, that is, the compressive strength is 1~
It is difficult to limit the weight to 5 kg/cm2.

There is also a filling method using cellular mortar, but even in this method, the quality of the cellular mortar cast on site increases due to material separation, and it is difficult to provide high fluidity with self-leveling. figure,
Furthermore, it is difficult to limit the strength to the same level as that of a mountain.

Furthermore, a lightweight embankment construction method is known in which an embankment is formed using styrofoam blocks, but since the bulk specific gravity of these blocks is 0.03, the light weight is a great advantage, but it is difficult to fill irregularly shaped areas. Difficult to stand,
It was almost impossible to apply this method to serving in areas other than the oven space.

This invention was made in view of the above circumstances, and its purpose is to provide stably treated soil that has high fluidity during filling, is homogeneous after solidification, and has strength comparable to that of a rock;
The objective is to provide a construction method using this.

[Means for Solving the Problems] Based on these objectives, the present inventor has made the assumption that excavated soil will be used, and has conducted intensive studies on materials whose bulk specific gravity can be appropriately reduced depending on the ground conditions at the pouring location. went.

As a result, among clay soils such as loam, clay, silt, organic clay soil, beet, and aggravated soil, which were previously difficult to reuse and had to be disposed of, we found that By using soil containing 40% or more of fine particles with a diameter of less than 75 μm and mixing and stirring water and a cement-based or lime-based solidifying agent, fluidity, solidification, and homogeneity can be improved. It was discovered that by mixing cream-like air bubbles prepared in advance with a foaming agent into this soil, stable treated soil with lightness could be obtained.Based on this knowledge, the present invention was completed. .

That is, the stabilized soil of the invention according to claim 1 of the present invention is obtained by adding and mixing water and a solidification agent to clayey soil containing 40% by weight or more of fine particles with a particle size of less than 75 μm. was used as a means of solving the above problem.

The stabilized soil according to claim 2 is a solution to the above problem, in which the stabilized soil according to claim 1 contains fine bubbles generated by foaming with a foaming agent or a foaming machine. .

In the construction method using stably treated soil according to claim 3, claim 1
Alternatively, the above-mentioned problem is solved by using the stably treated soil described in 2 for backfilling around pipes such as buried pipe installation trenches, and for backfilling retaining walls, bridge abutments, etc.

In the construction method using stably treated soil according to claim 4, claim 1
Alternatively, the above-mentioned problem is solved by filling the stabilized soil described in 2 into a cavity formed under the foundation of a structure on soft ground.

In the construction method using stably treated soil according to claim 5, claim 1
Alternatively, the above-mentioned problem is solved by supplying the stabilized soil described in 2 to an embankment on soft ground.

The present invention will be described in detail below.

The stabilized soil according to claim 1 of the present invention has, for example, a composition shown in Table 1 below, and these stabilized soils have the characteristics during filling and after hardening as shown in Table 2. It is something that you have.

As shown in these tables, the stabilized soil has a particle size of 7.
By adding a large amount of water to clay soil containing 40% by weight or more of fine particles less than 5 μm and further mixing with a solidifying agent, high fluidity or filling properties are ensured, and strength development equivalent to the strength of the ground is achieved. It is something that has been maintained. Furthermore, the stabilized soil had sufficient performance as a filler, as shown in Table 2 (based on its properties during filling and after hardening).

Table 1 Example of blending of stabilized soil This is a value indicating weight %.

Margin below The more liquid it is, the better it is. In the case of water, it takes about 9 seconds.

The breathing rate is the volume ratio of floating ice and serves as a measure of material separation.

In this case, as clayey soil, the particle size of the soil particles is 5 μm.
It is preferable to use residual soil in which the fine particles below the waterfall account for 40% by weight or more, and as such clay soil, green soil that has not yet dried is more effective and preferred, but powdered soil You can also use mud or muddy water.

Here, fine particles (for example, total amount of clay and silt)
The reason for setting the amount to 40% by weight or more is to prevent material separation even if a large amount of water is added to obtain fluidity. This is because the finer the particles, the larger the specific surface area, and particles with larger specific surface areas have higher water retention, which is effective in preventing material separation before curing.

In addition, especially when there are many clay particles, the electrical dispersion effect is strong (and effective.By the way, in volcanic ash clay soil such as Kanto loam, allophane and helosite are
In addition, general clay minerals contain a large amount of montmorinite, and these clay minerals have a particularly large specific surface area (
, which maintains a suspended state for a long time even if a considerable amount of water is added and mixed. In addition, these clay minerals have high reactivity with calcium ions, so that the reaction with cement or lime solidifying agents starts early, and the clay minerals harden before material separation begins. Due to the characteristics of the clay content, in the stabilized soil of the present invention, it is necessary to use fine particles with a particle size of less than 75 μm, which account for 40% by weight or more of the clay particles, or to use a homogeneous hardened soil. This will be effective in forming the

Figure 1 shows the relationship between the moisture content of stabilized soil using Kanto loam as the clayey soil, and the fluidity and breathing rate of the stabilized soil during filling. Figure 2 shows the relationship between the moisture content of the stabilized soil and the unconfined compressive strength of the stabilized soil after hardening.
In these figures, wA is the weight ratio of water to solid content in muddy water produced by adding water to clayey soil.

From FIGS. 1 and 2, it can be seen that no breathing occurs over a wide range of wA, high fluidity is obtained, and appropriate strength development is obtained.

Further, as the solidifying material, known materials such as cement-based or lime-based materials can be used.

In such stabilized soil, a foaming agent such as a surfactant may be used in advance, and the foaming agent may be foamed with a foaming machine to generate cream-like fine bubbles, and this may be mixed in. This makes the stabilized soil lighter. The fine bubbles generated in this case are strong bubbles that are difficult to defoam, and have a diameter of 100 μm! It is preferable to have a diameter of approximately That is, such fine pores can be mixed homogeneously, and after being mixed, they exist as closed cells. By incorporating such air bubbles, sedimentation and separation of soil particles can be suppressed,
Therefore, breathing can be reduced. In addition, by adjusting the amount of air bubbles, it is possible to obtain stable treated soil with a bulk specific gravity of up to about 0.7. Therefore, as mentioned above, not only can it be made lighter, but by selecting and using one with an appropriate bulk specific gravity depending on the purpose. It is possible to ensure high fluidity, strength development equivalent to the strength of the ground, and homogeneity, that is, material inseparability.

In this case, it goes without saying that the inclusion of air bubbles must be kept to a level that does not impair the properties of the stably treated soil of the present invention as described above.

Such stably treated soil has the following excellent advantages.

■ As shown in Table 2, it has high fluidity with a flow value of 15 seconds or less using the P funnel, and has sufficient pumpability.
That is, it has filling properties and strength development properties comparable to that of a natural rock, and as shown in FIG. 2, even if a large amount of water is added to obtain fluidity, the material separation property is low.

■ Because stabilized soil exhibits alkalinity, it does not corrode steel materials such as steel pipes and piles, and on the contrary, protects steel materials from corrosion.

■ Fine closed cells obtained by foaming the foaming agent can be homogeneously mixed in, thereby ensuring high fluidity, strength development equivalent to the strength of the ground, homogeneity, that is, material non-separability, and lightweight. It is also possible to achieve

Here, the reason why the air bubbles can be mixed homogeneously is that the air bubbles harden while being evenly dispersed due to the effect of fine particles, especially clay needles, and as a result, the stabilized soil with air bubbles mixed in becomes more homogeneous. is maintained.

■ By using lightweight stabilized soil, the earth pressure of backfilling and embankment can be reduced, which increases the safety of structures, suppresses and prevents ground re-settlement, and further improves the cross-sectional shape of structural members. It is possible to reduce costs by downsizing.

■ Stabilized soil containing air bubbles can be used as an underfloor insulation material because it is lightweight and has high heat insulation properties. It is possible to improve performance and reduce energy costs.

Utilizing the advantages of such stably treated soil, the present invention provides the following construction methods as described in claims 3 to 5.

That is, the construction method according to claim 3 uses the above-mentioned stably treated soil for backfilling around pipes such as buried pipe installation trenches, and for backfilling retaining walls, bridge abutments, etc. As mentioned above, the stable treated soil has high fluidity, which makes filling work easy, and there is little material separation during the process.
In addition, as mentioned in (2) above, the stabilized soil after filling does not corrode steel materials such as steel pipes and piles, and has the effect of protecting steel materials from corrosion.

The construction method according to claim 4 is for filling the above-mentioned stabilized soil into a cavity formed under the foundation of a structure on soft ground,
After all, the filling work is easier than in the above (■), and it has the effect of exhibiting strength comparable to that of a natural ground.If stabilized soil mixed with air bubbles is used, the effects described in the above (■) and (■) can also be achieved. Become.

The construction method according to claim 5 is for supplying the above-mentioned stabilized soil to the embankment on the soft ground, and from the above-mentioned (1), the embankment on the soft ground can have the same strength development properties as the ground. By using stabilized soil mixed with soil, it is possible to reduce the earth pressure of soft ground and embankments on soft ground, and to prevent sliding failure and control and prevention of ground subsidence, etc., as mentioned in (■) above. Become.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.

(Example 1) A five-story reinforced concrete housing complex is being constructed with a pile foundation on a newly developed site on soft ground with a thickness of about 20 cm containing humus soil. Ten years after construction, this housing complex experienced ground subsidence of approximately 1x, and cavities of approximately the same depth were created at the pile heads.

Therefore, the stabilized soil of the present invention was used and filled into the pile head and the lower part of the floor to restore the horizontal resistance of the foundation to the same state as at the time of construction.

The fillers (stabilized soil) used were 360 kg of Kanto loam and 528 kg of water as clayey soil, and Toughrock-3 as cement-based solidifying material in order to obtain the strength after hardening as described below.
A (trade name; manufactured by Sumitomo Cement Co., Ltd. Cement Co., Ltd.) (120 kg) was mixed with 210 kg of air bubbles generated using Sumishield A (trade name; manufactured by Sumitomo Cement Co., Ltd.) as a foaming agent. This is what I did. Regarding the physical properties of this treated soil, the bulk specific gravity is 1.
1. The flow value by P funnel is 12 seconds, and the strength after curing is -axial compressive strength 1 to 2 kg/cM1
It was strong enough to not stick to the pile.

Next, we will explain the method of filling this filler (stable treated soil), or first explain the manufacturing procedure of this filler.As shown in Figure 3, first, Kanto loam 1 and water 2 and are mixed in a high-speed rotating sludge mixer 3,
It turned into muddy water. In addition, in the desilting process to form this muddy water state, it is necessary to sufficiently disperse the soil particles in the water, and the quality of the dispersibility affects the characteristics of the filler itself. This is an extremely important process.

Then, the specific gravity of the mud water is adjusted to a desired value in this desilting process, and then the adjusted mud water is transferred to a mixing mixer 4, and a predetermined amount of solidification material 5 is added to the mixer 4 and mixed. did.

Next, a predetermined amount of cream bubbles foamed in the foaming machine 6 was mixed into the stabilized soil A obtained in the mixer 4 to produce a lightweight stabilized soil B.

The thus obtained lightweight and stabilized soil B of the present invention (as described in claim 2) is pumped and filled by the pump 7 into the pile head cavity under the foundation and the lower floor 9 of the above-mentioned apartment complex 8. did. In this case, since the weight-reduced and stabilized soil had sufficient fluidity, it was possible to perform pressure feeding and filling using the pump 7 well.

Furthermore, there was almost no re-settling after construction, and it was easy to manually excavate the filled lightweight and stabilized soil B even after one year had passed.

(Example 2) Using the stabilized dojin manufactured in Example 1 before weight reduction (before air bubbles were added), this was backfilled around the buried pipe 10 as shown in FIG.

As a result, since this stabilized soil had good filling properties, it was able to sufficiently spread into the narrow areas around the buried pipe 10, and it was possible to perform defect-free and homogeneous backfilling.

In addition, using the lightweight stabilized soil B produced in Example 1,
When the area around the buried pipe 10 was backfilled in the same way as above,
Similarly, it is possible to perform defect-free and homogeneous backfilling.
Furthermore, the earth pressure acting on the buried pipe 1o was significantly reduced, making it possible to suppress the generated stress to a low level.

In addition, after construction, the filled stabilized soil A or lightweight stabilized soil B does not have any unevenness on the surface even after it is opened to traffic, and it can be filled by hand.

Re-excavation was also easy.

(Example 3) Using the stabilized Dojin manufactured in Example 1 before weight reduction (before air bubbles were mixed in), this was filled as a backfill material for the retaining wall 11 as shown in FIG.

As a result, it was confirmed that this stabilized soil A had good filling properties.

In addition, using the lightweight stabilized soil B produced in Example 1,
When filled as a backfill material for the retaining wall 11 in the same way as above,
Similarly, the filling properties were good, and the earth pressure acting on the retaining wall 11 was considerably reduced, making it possible to suppress the generated stress.

In addition, after construction, the stabilized treated soil or lightweight stabilized treated soil B that was filled in did not have any unevenness on the surface even after it was opened to traffic, and it was easy to re-excavate with a shovel by hand.

[Effects of the Invention] As explained above, the present invention makes use of viscous soil, etc., which has been difficult to reuse in the past, among leftover soil generated from excavation work, etc., to create a filler material ( In addition to providing stable treated soil, it is also possible to reliably and effectively perform backfilling, backfilling, cavity filling, and embankment.

That is, according to the stably treated soil according to claim 1, it has high fluidity, so it has good workability in filling, for example, it can be easily pumped, and it has excellent filling properties and has a strength comparable to that of a natural ground. It has expressive properties and has extremely low material separation properties. Furthermore, since it exhibits alkalinity, it does not corrode steel materials such as steel pipes and piles, and can instead protect steel materials from corrosion. In addition, fine closed cells obtained by foaming the foaming agent can be mixed homogeneously, thereby ensuring high fluidity, strength development equivalent to the strength of the ground, and homogeneity, that is, material non-separability. Weight reduction can be achieved.

According to the stably treated soil according to claim 2, the inclusion of air bubbles reduces the weight and imparts high heat insulation properties, so it can be used as an underfloor insulation material, and in that case, it can suppress the diffusion of heat from under the floor. , it is possible to improve heat retention and reduce energy costs.

According to the construction method using the stably treated soil according to claim 3, the stably treated soil according to claim 1 or 2 can be used for backfilling around pipes such as buried pipe installation trenches, and for backfilling retaining walls, bridge abutments, etc. Since it is used for filling, filling work becomes easier and material separation during the process is reduced, and the stabilized soil after filling does not corrode steel materials such as steel pipes and piles, and protects steel materials from corrosion. . Furthermore, by using the stabilized soil according to claim 2, it is possible to reduce the burden of backfilling, thereby increasing the safety of structures, suppressing and preventing re-settlement of the ground, and reducing the cross-section of structural members. Therefore, it is possible to reduce costs.

According to the construction method using the stably treated soil according to claim 4, the stably treated soil according to claim 1 or 2 is filled into a cavity formed under the foundation of a structure on soft ground, so that the filling work is performed. In addition, by using the stabilized soil according to claim 2, the earth pressure of backfilling can be reduced, and the safety of the structure is increased. In addition, it is possible to suppress and prevent re-settling of the ground, and further to reduce costs by reducing the cross section of structural members.

According to the construction method using the stably treated soil according to claim 5, since the stably treated soil according to claim 1 or 2 is supplied to the embankment on the soft ground, the embankment on the soft ground can develop strength comparable to that of a mountain. In addition, by using the stabilized soil according to claim 2, it is possible to reduce the earth pressure of soft ground and embankments on soft ground, thereby preventing sliding failure, suppressing and preventing ground subsidence, etc. can be achieved.

[Brief explanation of the drawing]

Figures 1 to 5 are diagrams according to the present invention, and Figure 1 shows the adjusted mud water content ratio (WA) and the stable treated soil in an example of stably treated soil using Kanto loam as clayey soil. A graph showing the relationship between fluidity and breathing rate during filling, and Figure 2 shows the adjusted mud water content (WA) of an example of stably treated soil using Kanto loam, and the ~ after hardening of the stably treated soil. Graph showing the relationship with axial compressive strength,
Figure 3 is a diagram for explaining the manufacturing process of lightweight, stabilized soil and the filling of the lightweight, stabilized soil into pile cap cavities that occur under the foundations of housing complexes in subsidence areas. The figure is a side sectional view for explaining the filling around the buried pipe, and FIG. 5 is a side sectional view for explaining the filling of the back-filling part of the retaining wall. 9... Pile head cavity under the foundation and lower part of the floor, 10
... Buried pipe, 11... Retaining wall A... Stable treated soil, B... Light weight stabilized treated soil.

Claims (5)

[Claims] (1) Stabilized soil characterized by being obtained by adding and mixing water and a solidifying agent to clayey soil containing 40% by weight or more of fine particles with a particle size of less than 75 μm. (2) The stably treated soil according to claim 1, wherein the foaming agent contains fine bubbles generated by foaming with a foaming machine. (3) The stably treated soil according to claim 1 or 2 is used for backfilling around pipes such as buried pipe installation trenches, and for backfilling retaining walls, bridge abutments, etc. construction method. (4) A construction method using stably treated soil, characterized in that the stabilized soil according to claim 1 or 2 is filled into a cavity formed under the foundation of a structure on soft ground. (5) A construction method using stably treated soil, characterized in that the stably treated soil according to claim 1 or 2 is supplied to embankment on soft ground.