JP4610581B2 - Ground strengthening method - Google Patents

Description

  The present invention is a method in which a plastic gel injection material containing slag and an alkaline hardening agent as an active ingredient is pressed into the ground and the soil is formed while forming a lump of plastic gel over time or by pressure dehydration. It is related to a ground strengthening method that pushes particles around and forms a lump of plastic gel injection material itself in the ground to strengthen the ground.

  In particular, the present invention blends a plastic gel composed of a self-curing powdery material obtained by adding a very slight alkaline curing material to slag so as to obtain a predetermined fluidity, and statically press-fits it into a soft ground. Then, it is a ground strengthening method by compressing the surrounding earth and sand and increasing the density while forming a lump of the injection material itself in the ground.

  As a method of strengthening the ground by increasing the density by statically injecting the consolidated material into the ground and pushing the earth and sand to the periphery, conventional non-fluid low slump or almost slump-free injection material ( A construction method is known in which a mortar) is pressed into the ground to form a consolidated body in the ground, and the ground is consolidated and strengthened (see Patent Document 1).

  However, the above-mentioned known construction method requires a large device, and it is impossible to reinforce the foundation under construction or the foundation directly under the building where liquefaction prevention work or the like is performed.

  In addition, mortar mainly composed of flowable cement and plastic material such as water glass and aluminum salt are respectively transferred by a pump and mixed and mixed near the injection port to form a low flow plastic grout having a slump of 5 cm or less. There is also a cavity filling method that forms and injects, but if it is injected under pressure in soft ground, it will lose fluidity rapidly due to dehydration in the ground, and it will be difficult to form a massive gel that expands, or it will be impossible to inject It is difficult to improve the ground because it splits out of the middle range and deviates like a pulse.

  The present applicant has previously developed a ground strengthening method that presses a plastic gel into the ground to strengthen the ground, but has further conducted various experiments to form a large lump in the ground. As a result of the development, the inventors have found conditions for the plastic gel containing slag as a main component to expand in the ground (see Patent Document 2 and Patent Document 3).

  The inventors of the present invention have used a simple technique called an injection method, and have studied the flow characteristics and strength expression that fluctuate over time after blending a plastic gel injection material containing slag and an alkaline curing agent as an active ingredient. The present invention has been completed by confirming that, under certain conditions, a massive solid body can be formed under certain conditions.

  When suspension grout or instantaneous grouting is injected into the ground, it is difficult to form a hardened lump in a predetermined area because the ground is split and injected into a vein shape. The inventor of the present invention forms a lump of a plastic gel in the ground by press-fitting a plastic gel injection material formed by adding a curing agent to the slag in the ground or further adding a water retaining material. It is possible to increase the density of the surrounding ground by enlarging the lump of plastic gel formed with dehydration in the ground while it is fluid during the injection process. It is a thing.

  In this process, these plastic gel injection materials are controlled by the injection method and injection management system that have been upgraded in recent years, so that a predetermined amount of massive gel can be placed in the unit volume of the injection hole without causing splitting in the ground. They found a method to form a hardened body and succeeded in increasing the density of soft ground.

  Conventionally, a mortar injection solution containing cement as a main material has a slurry-like fluidity and solidifies by a hydration reaction. When such a fluid mortar is injected into the ground, it is injected by splitting the ground and easily deviates, and large breathing occurs. The material separates and settles in the ground and solidifies in a pulse shape.

  On the other hand, in order to reduce the breathing, it is sufficient to increase the cement content. However, if this is done, the hardening of the cement will be accelerated and it will not be possible to fill a wide area, or the ground will split and escape. There is. A method of using aluminum or water glass as a plastic material for fluid mortar mainly composed of cement has been proposed, but such plastic grout is suitable for filling the cavity, but this was pressed into the ground. In some cases, the viscosity is so high that it hardens rapidly in the ground, making it impossible to inject, or splitting easily.

  Also, cement suspension and plastic material are pumped separately, and a slump formed by joining before the injection pipe is pressed into a ground with a plastic grout of less than 5 cm, compressing the surrounding soil particles. A ground strengthening method has also been proposed.

  However, if the slump is less than 5 cm, it is about 8 cm in the flow by the cylinder, and it is somewhat different depending on the material constituting the grout, but it is about 10 cm in the table flow. In this case, the gelled product hardly moves even when vibration due to dropping is applied. When such a low slump plastic grout is poured into the ground, moisture and powder are separated in the ground, and the fluidity is further lost due to dehydration, resulting in rapid hardening and the plastic holding time cannot be obtained. As a result, the injection pressure increases and the injection becomes impossible or the ground is split like a vein and escapes in an unspecified direction, so that the ground reinforcement effect cannot be obtained.

  Therefore, as a result of various studies, the present inventor noticed that the fluidity of plastic grout changes not only with time but also with dehydration. Even after being pressed into the ground, it loses its fluidity over time or by pressure dehydration to form a plastic gel, which pushes the soil particles to the periphery while maintaining a long flow holding time while it becomes a lump. This is a ground strengthening method that makes it possible to form a large lump in the ground and to strengthen the ground.

Japanese Patent Laid-Open No. 06-108449 JP 2007-009194 A Japanese Patent Laid-Open No. 2007-077794

  For the above-mentioned purpose, the ground injecting material for ground reinforcement and the ground strengthening method require liquid flowability in a hose as long as several tens of meters. On the other hand, when pressed into the ground, it does not penetrate between the soil particles. In addition, while maintaining the fluidity in the ground, a lump is formed at a specified position without deviating by splitting outside of the specified improved range, and the lump is grown as large as possible by the injection solution itself, and solidified. It is required to simultaneously satisfy the conflicting characteristics of pushing the surrounding soil particles and increasing the density of the surrounding soil by that amount.

  Therefore, the present invention uses slag, which is an industrial by-product, as an active ingredient, and is blended so that a predetermined flow characteristic can be obtained. In addition, an extremely small amount of an alkali-curing material, that is, cement, lime, plaster, A wide range of alkaline materials such as bicarbonates, carbonates, phosphates containing condensed phosphates, aluminates, caustics, etc. and water are blended at a specified ratio, or water retention and fluidity are improved. In order to reduce dehydration and expand the lump before solidifying in the ground, bentonite, clay, silt, polymer agent, water absorbent, etc. are blended, or further gelation accelerator, gel Addition retarder, thickener, peptizer, foaming agent, press into the ground under the specified conditions, and it is possible to create a lump or lump of solid with plastic gel in the ground To clarify the flow characteristics and consolidation characteristics Which was succeeded in achieving ground reinforcement, to solve the problems existing in the known techniques described above, or to provide a ground injection material and ground reinforcing method was developed. Of course, this method not only aims to increase the density by forming a lump in soft ground, but also can be used for structural foundations by forming a pile that also has an effect as a compression pile or tensile pile. This is a ground strengthening method that can also be applied to stabilization of the slope.

  In the present invention, the plastic gel injection material forms a lump in the ground and further enlarges the lump to strengthen the ground. Focusing on the fact that this technique becomes a problem, these problems have been solved by developing an injection material, an injection method, and a management method thereof.

  1) Conditions for an injection material in which a plastic gel is formed in a lump shape within a predetermined holding area without penetrating between soil particles and does not deviate from the injection range, and the lump is expanded while keeping the lump shape. .

  2) A method of compressing the surrounding earth and sand by expanding in the lateral direction.

  3) A method of improving the soil density by a simple method of pouring under ground conditions that are high enough to be press-fit with the plastic gel itself but too low for the ground.

  4) A technique for minimizing the transfer of the consolidated body in the vertical direction.

  5) A technique that can reliably increase the strength by minimizing ground departure and ground uplift in areas close to the ground surface.

  6) A technique that makes use of the construction method of the injection method and enables long-distance liquid delivery.

  7) Development of an injection management system that enables the above.

  The inventor found that the fluidity until the injection solution was injected into the ground, the fluidity in the ground, the formation of a lump without penetration between soil particles and split injection, and the growth to a large diameter. In order to solve this problem, the slag and water mixture, or the mixture of slag and a small amount of alkaline hardening material, is reduced in fluidity in the process of dehydration in the ground, and a lump is formed in the ground. Focused on. And as an index indicating the above flow characteristics of the injected liquid in the ground, 1) flow and slump value indicating fluidity, 2) gelation time by plastic gel, 3) plastic retention time, 4) non-plastic state We focused on the solidification time.

Among these, the gelation time is the time when the table flow is 20 cm after blending, and the plasticity retention time is the time when the gel does not flow even when external force is applied after gelation, that is, the penetration resistance value exceeds 0.01 MN / m ² . It was set as the time until the time point. We paid attention to the fact that these are greatly affected by the change of water powder ratio due to the phenomenon of press-fitting dewatering in the ground.

  In addition, if the amount of the alkaline curing agent is small, the strength development will be slow, so that it will expand greatly into a lump without forming split injection while maintaining fluidity in the soil to form a consolidated body by the injection material itself I found out that I can do it. In this case, the relative density and the static earth pressure coefficient are increased by expanding the consolidated body and compacting the surrounding ground. It paid attention to the fact that the horizontal stress applied to the consolidated body increased by this, and the high peripheral frictional force with the surrounding earth and sand was exhibited, and the integration with the surrounding ground could be maintained.

  As a result of various studies to solve the above problems, the present inventor has found the following.

(1) Slag is a latent hydraulic material that can be cured by forming a hydrate by a hydration reaction. However, slag does not start a hydration reaction under normal conditions. To reveal. Therefore, the injection material that has started the hydration reaction with the alkaline curing agent causes a decrease in fluidity over time, and forms a plastic gel when the water powder ratio decreases with dehydration in the ground, Furthermore, it solidifies through an unplasticized gelled product. Such a phenomenon can sufficiently achieve the effects of the present invention as long as a lump formed by acceleration in the ground by dehydration has a higher strength than the surrounding ground.

(2) The table flow, slump, and cylinder flow indicate the fluidity of the slag or the injection solution to which the hardening agent is added. The table flow is in the range of 14 cm to 28 cm and the slump is in the range of 10 cm to 28 cm. Is about 9-26 cm, table flow is about 20 cm, slump is about 21 cm, cylinder flow is about 15 cm, and it becomes a plastic gel. Will decline. By controlling the ratio of the powdered body consisting of slag and powdery alkaline hardening material, and the ratio of hardening material in the whole powder, the plastic flow characteristics in the ground and the plasticity in the ground are controlled. Additives such as accelerators, retarders, fluidizers, peptizers, foaming materials, etc., to adjust the expansion of the gelled product and further the gelation time until reaching the plastic gel and the holding time of the plastic gel It is possible to adjust the workability and the size of the plastic gel. If the water powder ratio is too small, or if the ratio of the cured material is too large, the expansion of the columnar improvement body in the ground is inhibited by dehydration, so that ratio is important.

  Especially when the ratio of hardened material is large, strength development appears early, so it hardens immediately from the plastic state, and not only prevents the gel from spreading in the ground, but also a large concrete body is made against the surrounding soil In the same way, the integration of the entire ground is hindered, and the earthquake resistance of the improved ground is lowered because a large local stress is generated and destroyed during an earthquake. In addition, the fluidity injection material that forms a lump by dehydration in the ground can contain not only slag but also soil generated in the field, silica sand, etc., and clay, thickener and water retention material can be added to it. The fluidized soil has a predetermined flow characteristic, that is, a flow and slump value, and is adjusted so as to exhibit a predetermined water-powder ratio, and when dehydrated to a flow of 20 cm or less, it becomes a plastic gel and does not penetrate between soil particles. It is possible to improve the predetermined ground by making the surrounding ground denser by injecting so as not to deviate from the crack. If a hardening expression material is further added as the material, the strength increases.

(3) The fluidity of the ground injection material varies with time during the liquid feeding process and the press-fitting process into the ground. By effectively using the change in flow characteristics, solidified bodies can be formed in the ground, but this makes it difficult to adjust the composition of the injection solution and control the injection. Management system becomes important.

(4) Workability suitable for kneading and pumping of the ground injection material and press-fitting into the ground is 12 cm or more, preferably 14 cm or more and 28 cm or less, and slump larger than 5 cm, preferably slump is 10 cm or more and 28 cm or less. Is larger than 8 cm, preferably 9 cm or more and 26 cm or less. The determination of the water / powder ratio that governs the slump and flow greatly affects the workability and the creation and expansion of columnar improvements in the soil. It is possible to accurately determine the fluidity that changes sequentially with time, and to control the water powder ratio and the hardening material ratio by slump and flow to quickly adjust the composition and the liquid powder ratio. It is important to build a columnar improvement body.

(5) When an additive is added, the gel time for forming a plastic gel according to the amount added can be adjusted. By adding bentonite as a thickener or an aluminum sulfate salt as a promoter, the flow can be easily reduced or the gelation time can be shortened. The slump can be reduced from around 20 cm to about 10 cm. In addition, by forming a plastic gel with dehydration in the ground and continuing the press-fitting for a longer time for the gel to remain in a plastic state, the plastic gel grows and forms a large plastic improvement body in the ground. It can be changed to a cured product through a plastic gel.

(6) On-site generated soil such as clay and earth and sand, quartz sand, coal ash and the like can be added as aggregates. Aggregate not only serves as an extender, but also helps to adjust consolidation strength and fluidity. Generally, the strength decreases as the ratio of aggregate in the powder increases, and the fluidity decreases as the particle size of the aggregate increases.

  Fine particles such as silt and loam in clays such as bentonite and on-site generated soils, polymer agents, etc. are excellent as water retention and thickening agents, and act as a binder to the powdery body by delaying the dehydration of the press-fitted material in the ground. It acts as a fluid having pseudo-bonding properties, and forms a plastic gel mass without separating and dispersing, and helps to expand it.

(7) Cement-based suspension grout is very viscous, but if it is made plastic, the resistance to press-fitting from the injection port of the injection tube that opens into the ground and the liquid feed tube to the injection port There is a problem that the liquid feeding resistance is extremely large and is easily clogged in the liquid feeding pipe and the pump. For this reason, if a thin composition is used to facilitate liquid feeding, it becomes a vein in the ground. For this reason, in the prior art, as with backfill injection, a cement-based suspension with good fluidity and a plastic material are mixed at a point before being sent to the injection tube to instantly make it plastic and slump into the ground. A method for press-fitting plastic grout of less than 5 cm has been proposed. However, the cementitious plastic grout plasticized in front of the injection tube immediately becomes high strength due to dehydration in the ground, so it is difficult to grow into a large lump gel, and it is impossible to inject due to the high injection pressure. Or destroy the ground and deviate.

  The present inventor has noted that the injection of ground improvement that compresses the surrounding earth and sand by press-fitting into the ground to form a large gel, compared to injection of plastic grout for backfill injection and void filling, has been noted. .

  As a result of research, the present inventor has found the following necessary conditions for the plastic gel injection material not to be deviated by splitting and forming a large lump in the ground, and the mechanism of the formation and expansion of the plastic gel improved body. It was.

1. The ground injection material is fluid until it is injected into the ground, but after it is injected into the ground, the ground injection material should not break by splitting the ground.

2. The ground injection material reaches the plastic gel before being injected into the ground, or is injected into the ground and reduced in fluidity by pressure dehydration to form an improved plastic gel. thing.

3. The improved body retains plasticity in the ground, and the improved body is expanded by being pushed and expanded by a plastic gel that is subsequently pressed into the interior. As a result of being expanded at the outer peripheral part of the improved body, it is further dehydrated to become non-plastic and loses its fluidity, and with time, a solidified band is formed from the outer peripheral part to form a large improved consolidated body. Statically compacted by reducing and expanding the voids in the earth and sand.

4). Since the inside of the plastic improvement body retains the plastic shape, if there is further injection of the injection material, some solidification zones on the outer periphery of the lump are torn, and the plastic gel is pushed out to the periphery. It dehydrates and becomes non-plastic, and the plastic gel mass expands. When the lump becomes harder than a certain level, it becomes difficult to break it with normal pump pressure, making it impossible to press fit. That point will be the size of the improved consolidated product.

  As a result of research, the inventor has found that fluidity is maintained even after being pressed into the ground from the tip of the injection pipe installed in the ground without causing resistance pressure in the liquid feeding pipe during pumping or clogging in the pump. And forming a plastic gel having a plastic holding time (a time when it is pressurized to be in a fluid state) in the ground by press-fitting the injection material that exhibits a plastic shape even when dehydrated, The present inventors have found that the improved body grows and completed the present invention.

  Such characteristics have not been known so far. That is, the fluidity injection material is fluid when it is pressed into the ground, and as the press-fitting continues, the grout is dehydrated and the water-powder ratio is reduced from 70% to 60%, further 50%, and after 3 minutes. It shows that a plastic gel is formed, it is greatly formed as a gel, and becomes a non-flowable gel and solidifies as the dehydration or curing phenomenon progresses.

  Therefore, even if it does not exhibit plasticity at the time of injection, it can become plastic by dehydration in the ground. In the injection of such fluid injection solution, even if the compounding solution is injected as a single solution, the powder injection solution is A solution and the gelation promoting material such as aluminum water glass is used as B solution. The liquid A can be applied regardless of the means to use the liquid A as a plastic gel and the liquid B as a gelation accelerator using an alkali material such as water glass.

  As a result of the above research by the present inventors, a reliable ground strengthening method that can be designed by increasing the density by press-fitting a plastic gel injection material to form a large lump in the ground as described below becomes possible. It was.

1. The infusion solution itself is fluid by the pump, but the one injected into the ground will split into veins so that it will not penetrate and solidify indefinitely. This is because only when a solid aggregate is formed by gelation within the range of each injection hole, the soil particle gap in that range decreases and the density of the ground between the injection holes around the mass is increased. This is because it can be expected with certainty.

2. The material injected into the ground is prevented from penetrating between the soil particles, and the soil particles on the ground between the plurality of injection holes are pushed away by a lump. This is because if the injection solution penetrates between the soil particles, the ground between the plurality of injection holes cannot be compressed, and an increase in density due to the compression of the ground in the range of the injection holes cannot be expected with certainty. .

3. The gel press-fitted into the ground forms a consolidated body in a lump shape and grows into a large-diameter consolidated lump. For this,

(1) As the injecting material, a mixture of slag and water has a slump of more than 5 cm or / and a table flow of 12 cm or more and / or a cylinder flow of more than 8 cm, or a slump within 28 cm or / and a table flow of It is formed by using a fluid ground injection material with a flow of less than 30 cm or / and a cylinder flow of less than 28 cm, or a ground injection material mixed with an alkaline hardening material and press-fitting it into the ground. The soil particles are pushed to the periphery by enlarging the lump made of the injection material itself to form a lump in the ground and strengthen the ground.

(2) The ground injection material can reach a table flow of 20 cm or less by dehydration. Here, the time when the table flow becomes 20 cm is regarded as the time when the plastic gel is formed.

(3) As the dehydration proceeds, the ground injection material passes through a plastic gel and becomes non-plastic and solidifies.

(4) The ground injecting material is curable fluidized soil or non-hardened fluidized soil, and loses fluidity by dehydration, and the table flow reaches 20 cm or less and develops strength equal to or higher than the surrounding ground. To do.

(5) If the ground injection material is a mixture that becomes a plastic gel when the water-powder ratio is reduced by less than about 20% by weight, it will become a plastic gel if it continues to be pressed into the ground to form a massive solid body. Is done.

  The following conditions are preferable in order that the lump by the plastic gel grows greatly in the ground to form a consolidated body.

4). Near the ground surface, the ground tends to rise, and the injected solution tends to deviate to the ground surface.

5. The ability to maintain fluidity without separation in a long-distance liquid feeding pipe enables workability for applying this technology to seismic reinforcement of ground where buildings are densely packed.

6). Make it applicable not only to sandy ground but also to viscous ground.
In the route that is injected into the ground from the blending system of the injected solution through the liquid feeding tube and the injection tube line, while maintaining fluidity (the above requirement 5), the above 1, 2, 3, 4 or 4 is satisfied.

  In order to shorten the time until the plastic gel is exhibited, it can be adjusted by adding an alkali-curing material. That is, they act as gelation accelerators that stimulate and initiate the hydration reaction.

In the ground injection material of the present invention, the alkaline hardening material added to the slag as the main material constituting the suspension is 0.1 % by weight or more and less than 1% by weight in the powdery material used. The water powder ratio is 30 to 200% by weight, preferably 40 to 150% by weight, the table flow is 12 cm or more and less than 30 cm, preferably 14 to 28 cm, the plastic holding time is about 10 hours or more, and the breathing rate is within 10%. Preferably, the injection material is within 5%, the slump is larger than 5 cm, preferably 10 to 28 cm, and the flow through the cylinder is larger than 8 cm and less than 28 cm, preferably about 9 to 26 cm.

In Patent Documents 2 and 3 according to the present inventor, the ratio of the cured material when the alkaline cured material is used together with the slag is 1 to 40% by weight, preferably 1 to 20% by weight. Even in extremely small amounts of 0.1 % to less than 1% by weight, which is contrary to previous expectations in the research, the latent hydraulic properties of the slag are manifested, and the strength development is delayed due to the small amount of the alkaline hardening material. The purpose of use is to increase the density by compressing the surrounding earth and sand by statically press-fitting such a plastic gel having a predetermined fluidity into the ground to form a lump with the injection material itself in the ground. It has been found that there is an extremely excellent effect in its handling.

  As described above, the present invention uses a suspension obtained by adding a very small amount of an alkaline curing agent to slag, but the type and combination of the granule materials to be used and the specific blending ratio are used. The desired injection material exhibiting flow characteristics and consolidation characteristics according to the pressure is pressed into the ground, and by forming a lump in the ground, the soil particles surrounded by the injection holes are pushed around the ground. The ground can be strengthened by compaction, and further by a consolidated body closely and integrated with the ground.

  A ground injecting material that forms a plastic gel that can flow by pressurization, but does not penetrate between soil particles and does not split into veins, in order to consolidate in the ground. Ground press fit material showing a range of 12 cm or more and less than 30 cm, preferably 14 to 28 cm for a slump, greater than 5 cm, preferably 10 to 28 cm for a slump, and greater than 8 cm to less than 28 cm, preferably about 9 to 26 cm. It is preferable that In addition, considering the formation of a plastic gel by pressure dehydration in the ground, the plastic gel before injection or the water-to-powder ratio is reduced by about 20%, and the plastic gel (with table flow) It is preferable that it is approximately 20 cm).

  If the flow value or slump is below this level, it will be difficult to grow a solid aggregate of plastic gel in the ground, and if it exceeds this value, it will be split and injected into veins or cracks before it can be dehydrated to form a lump. Hateful.

The slag used in the present invention is preferably blast furnace slag, and may be a general product such as ordinary 4000 (cm ² / g) brane, or more than that, ultrafine particles such as 6000 to 15000 (cm ² / g) brane. Slag may be used.

  In the present invention, as described above, a slag (S material) is blended with a very small amount of an alkaline curing material and water at a specific ratio, and as the alkaline curing material, hydrogen carbonate such as cement, lime, gypsum and sodium hydrogen carbonate is used. Any one of alkali carbonates such as alkali, calcium carbonate, and magnesium carbonate, caustic alkali, or a plurality of groups (C material) and water (W material) are mixed. Further, a fluidity adjusting material (B material) is blended so as to obtain a predetermined fluidity.

  In this case, the composition and the water / powder ratio are selected by filling the mold with a porous stone or filter paper on the top and bottom and filling it with a cylinder at a pressure corresponding to the assumed injection pressure and dehydrating it. After measuring and injecting the strength of the test specimen, it can be set to have a strength equivalent to or greater than the strength corresponding to the average soil density of the surrounding soil. The water powder ratio is 30 to 200%, preferably 40 to 150%. Here, the cured material ratio is C / (S + C + B) × 100, the water powder ratio is W / (S + C + B) × 100, and S, C, B, and W are weights.

  When such a liquid mixture is mixed, it remains as it is if the water powder ratio is small, and when the water powder ratio is large, it becomes plastic sooner or later by dehydrating in the ground. The plastic gel flows when force is applied, but stops flowing when it stops. The gel time for forming a plastic gel is when the table flow is approximately 20 cm. The flowable injection material exhibiting the above water-powder ratio, flow, and slump is left as it is or by adding an additive and dehydrating under pressure in the ground to form a plastic gel even when the water-powder ratio is large. A gel mass can be formed.

  The lump formed in the ground needs to be enlarged over a wide range as much as possible to form a large lump consolidated body while having a low fluidity. For this purpose, the flow, slump and water / powder ratio are important, and the ratio of the curing material and the additive are also important.

  It is difficult to expand the lump in the ground because the strength development occurs rapidly when the ratio of the cured material is excessive, and the fluidized plastic gel consolidates in a short time. Although it was recognized also in 2 and 3, in this invention, since the ratio of an alkaline hardening expression material is less than 1 weight%, naturally, onset of strength occurs quickly, and from a fluid plastic gel in a short time. There is no problem of consolidation.

On the other hand, in the case of not containing any hardening developing material, there is a possibility that the latent hydraulic property of the slag may not be sufficiently exhibited. However, even if 0.1 % by weight of the alkaline hardening developing material is mixed, the latent hydraulic property of the slag may be stimulated. it can. In addition, when the amount of water is large, water separates and breathing increases, and it is difficult to form a plastic gel. For this reason, the ratio of the cured material in the present invention is 0.1 % by weight or more and less than 1% by weight, and a massive solidified product is formed which has grown greatly through the plastic gel in the ground.

  The strength development can be delayed by setting the ratio of cured material to 1% by weight or less, and it is easy to expand due to the long plastic gel retention time in the ground, and the improved ground also has uniform strength and density. It is integrated with the raised surrounding ground and has excellent earthquake resistance.

  Further, in the present invention, an additive is added so that a hard suspension composed of slag, an alkaline curing material and water has a predetermined fluidity. As additives, fluidity can be adjusted by aggregates such as bentonite, clay, on-site generated soil, coal ash, and incinerated ash.

In addition, an aluminum salt such as aluminum sulfate or polyaluminum chloride that can adjust the time for developing plasticity can be added to a hard suspension composed of slag, an alkaline curing material, and water. In this case, a blended grout having an aluminum ratio of 2.0% by weight or less, preferably 0.1 to 1.0% by weight and 0.01 to 0.35% by weight in terms of Al ₂ O ₃ is used. Here, the aluminum ratio is aluminum material / (S + C + B) × 100. Aluminum material represents weight.

  In addition, the ground injection material of the present invention can be added with a foaming agent or a foaming agent to improve fluidity and reduce weight, and clay, bentonite, polymer thickeners such as polyvinyl alcohol and carboxymethyl. Addition of cellulose (CMC), methyl cellulose, etc. suppresses dispersibility in water, reduces sedimentation, improves workability or serves as a water retention material and as a binder for slag as the main material, A fluid having a structure that is difficult to disperse while maintaining fluidity by forming a pseudo gel. As a result, the dehydration in the ground is reduced and the expansion of the blockiness is promoted.

  The present invention should be called a static plastic gel press-in method, and does not generate vibration or the like in a large machine like a sand compaction method, and a non-fluid mortar like a low slump mortar press-in method. Large equipment is not required unlike the press-fitting method. For this reason, the construction method of the present invention can be said to be a construction method having excellent workability with no pollution because it can be easily constructed statically and without noise and in a narrow work area using a simple apparatus used in a normal injection construction method. In addition, since it can be injected through an injection pipe that can be installed by boring in a curved shape, it can be injected obliquely under the building, horizontal injection, as well as seismic reinforcement injection directly under the building combining curved and horizontal. The construction method of the present invention will be described below.

  The above-mentioned ground injection material according to the present invention is pressed into the ground through the injection pipe inserted into the ground, and the soil particles are pushed around and solidified into a lump while pushing the surrounding soil and reinforcing the ground, the same principle It is suitable for the restoration injection method for buildings submerged in It can also be expanded to a columnar shape to increase the effect as a pile, and can be applied as a composite pile by using cast-in-place piles, rebars, and steel pipes, and can also be applied to stabilize slopes and slopes as anchors. You can also

  Furthermore, the plastic gel injection material according to the present invention can be injected from a plurality of injection points to constrain the ground between the injection points, and the ground density between the injection pipes can be increased to consolidate the ground. In order to expect such an effect, it is desirable to install a plurality of injection pipes on the ground at intervals of 0.5 m or more and 3 m or less. If it is more than this, the integrated ground improvement effect of the entire press-fitted ground due to the density rise cannot be obtained, resulting in local ground improvement. When the injection material of the present invention is press-fitted into the ground, if the ground is a viscous soil or a ground with a viscous soil layer interposed, a drain material is installed in the ground, and the plastic gel injection material is dehydrated or ground. It is more effective to press fit while promoting dehydration.

The above-described injection is performed using, for example, the injection pipes shown in the following (a) and (b).
(A) An injection tube having a drilled portion or a discharge port at the tip.
(B) Injection is performed using an injection tube having a plurality of discharge ports in the axial direction.
(C) An injection pipe provided with at least one bag packer in the outer pipe.
(D) An injection pipe provided with a water suction port covered with a discharge port and a water-permeable material in the pipeline.

  If an excessive amount of plastic gel is formed in the ground at the same time in order to greatly improve the strength of soft ground, etc., the ground surface will be raised, the ground will be destroyed laterally, There is a tendency that the strength of the ground does not improve as set. For this reason, it is desirable to take advantage of the characteristics of this ground injection material and to increase the injection amount by injecting at a low discharge amount at the initial stage of injection, gradually increasing the injection pressure, and continuing to press fit within a predetermined injection pressure range. The strength of the ground before injection (N value, etc.), the injection depth (top loading pressure), the injection pressure, the injection amount, and the area of each piece can be used to determine the improved strength after injection. Or more accurate if the ground displacement is taken into account.

  In addition, fluidity is present during the injection, and when the injection is stopped, the fluidity stops and gelation or pressure dehydration occurs, and a pseudo-solid state appears. Inject at repeated intervals) to make it quasi-solidify, compacting without destroying the injected ground, disperse the excluded water among the surrounding soil particles, It is also effective to perform dehydration, increase the consolidated diameter of the gelled product, or inject these grouts with a certain time lag (time difference).

  For example, in the case of vertical injection, the injection is performed by repeating the interval method, and the ground injection material is injected into the ground injection material previously injected, and the ground is split. Without repeating, the ground injection material is repeatedly press-fitted to perform consolidation dehydration on the side of the ground and strengthen the ground. Alternatively, a predetermined number of holes are formed in a predetermined area of the ground, and the ground injection material is not injected into the ground injection material at a single point through the predetermined time lag for each hole. As described above, the design injection amount can be divided into several parts.

  In this way, the plastic grout of each drilling hole is injected with each soil layer at each predetermined time lag by an interval method for each stage, and the plastic grout previously injected consolidates the surrounding ground, or by itself, Alternatively, when the injection solution is dehydrated, the ground injection material to be injected into the predetermined number of holes is added to the ground of each hole by each soil layer or each stage. Similarly, it is possible to perform consolidation dehydration on the side, increase the strength, suppress the displacement as a whole, and enhance the strength of the ground in the predetermined area.

  For example, an injection tube with a discharge port at the tip is inserted up to a predetermined depth, and the step of pulling up the injection tube is stepped up so that the discharge port is positioned within the range of the plastic gel before becoming a non-plastic gel. Enlarge and press the gel lump. Furthermore, the bag body is set in an area near the ground surface in the injection tube to be inserted into the drilling hole, the suspension type grout is press-fitted inside, the bag is inflated to the periphery, and the surrounding ground is consolidated. By improving the ground surface without deviating from the plastic gel injection material and press-fitting the ground injection material from below the bag body, the plastic body does not get over the bag body cured body, and the bag body Due to the restraining effect of the above, there is no displacement of the ground uplift and the like, and the strength due to the ground dewatering action can be achieved over the entire area, and the strength can be improved over the entire region.

  In this case, it is preferable that the installation area of the bag body is within a depth close to the ground surface, for example, within a 3 m range (particularly, a 1.5 m range). This is because even in a plastic gel, this region tends to deviate to the ground surface. For the same reason, it is possible to equalize the compression of the ground surface and prevent the ground surface from being raised by installing injection holes densely in a region close to the ground surface. This is because in a region close to the ground surface, for example, within 3 m (especially within 1.5 m), if a large amount of injection is performed from one injection hole, there is little earth covering, so it is easy to deviate to the ground surface and to easily raise the ground. Because. Therefore, in this region, the vicinity of the ground surface can be uniformly strengthened by making the injection hole denser than the region having a large depth and reducing the injection amount per one.

  In addition, the ground improvement on the ground surface is likely to cause a ground uplift due to a low overlay pressure, and the ground uplift reaches a diameter of several m on the ground surface. Therefore, the injection hole to be injected is not transferred to the adjacent injection hole, but is transferred to the injection hole outside the influence range of the ground uplift, and the injection of the adjacent injection hole is performed when the ground uplift is cured. desirable. In the area close to the ground surface, the injection step is shifted from the upper part to the lower part, the ground injection material is press-fitted to compress the ground near the ground surface, and then the injection pipe is inserted to the bottom of the improved ground. By shifting the injection step upward from the base, the ground surface ridges can be reduced by the injection, or the lower restraint can be reliably improved by the upper restraint effect.

  In addition, in order to eliminate moisture in the soil when the plastic gel injection material is injected into the ground, a drainage drain material is also provided so that intermittent drainage effect (injection after a while) (injection) It is possible to promote the side consolidation dehydration effect of the ground by dehydrating during suspension of the soil or to accelerate the dewatering of the plastic gel injection material (the application of this drain material will strengthen the soil of the viscous soil layer) Suitable for). Alternatively, drainage pipes are installed to remove groundwater and increase the speed of consolidation. By providing a water inlet in addition to the outlet on the side of the pipe, the drain effect can be achieved by sucking in excess water or soil water from the inlet through the inlet while pressing the inlet from the outlet.

  Furthermore, in order to measure changes in the ground uplift, etc., a sensor such as a laser measures the change in real time and grasps the amount of compression of the ground, or responds immediately when the change causes an abnormal design. The injection of plastic grout is adjusted, or the injection volume and injection depth are changed via the controller of the injection device, or the specific gravity of the injection solution, injection volume, interval time, etc. are automatically switched. Thus, the ground strength can be reliably improved by moving to another stage before exceeding a predetermined displacement and by compaction dehydration as designed.

  In addition to measuring the ground uplift on the ground surface, the above ground displacement can be measured by setting a measuring rod with a strain gauge in the ground to know changes in the ground part in the measuring direction. A pore water pressure gauge can be provided to determine the consolidation dewatering status.

  FIG. 1 shows the injection arrangement. In this invention, when the ground injection material is pressed into the soft ground from the injection pipe at a low speed, the plastic gel exhibiting fluidity expands the range of the bulk gel while the injection pressure is applied. In the advanced part, the water content of the grout is reduced by dehydration to the surrounding soil particles by the injection pressure, the fluidity is lost, and the plastic gel is changed to the non-plastic gel. In this way, the density of the soil between the injection holes is increased, the strength of the ground is increased, and the ground is strengthened. The injection hole interval is effectively 0.5 to 3.0 m depending on the quality, the target improvement degree, and the size of the soil cover.

  Next, a mode to be implemented by the present invention will be described as an embodiment mode with reference to FIG. In this case, as shown in FIG. 2A, the rod injection tube is used to sequentially inject from the bottom to the top or from the top to the bottom. Alternatively, a double pipe double packer injection outer pipe may be installed to inject from the inner pipe through a plurality of discharge ports. In this case, it is preferable for enlarging the gelled product to move the stage so that the discharge port is located in a range in which the plastic gel in the ground is in a state before becoming the non-plastic gel.

  The embodiment of FIG. 2 (b) shows an aspect of the basic example of the interval system, and the drilling hole 4 is formed in a predetermined soft ground 3 and similarly in a conventional manner in the same manner in a lateral direction with a predetermined pitch. Is formed at a predetermined depth, an injection pipe 9 (not shown) is inserted into the drilling hole 4, and a suspension type plastic grout is injected from the injection apparatus (not shown) on the ground to a predetermined stage of the injection pipe 9 by an interval method at a predetermined time lag. The injection is performed in series while being converted, and is repeated through a predetermined step-up or step-down, and the injection is repeated for each zone of the ground 3 in a chasing manner. In this case, an injection tube rod may be used as the injection tube, or injection may be performed by inserting the injection inner tube into the outer injection tube and moving the injection stage.

  In this case, the injection in each cycle is injected at a low pressure so that it does not deviate in the initial stage of injection, and it is injected while draining the ground 3 or dehydrating the injection solution, and after a predetermined timing, When the pumping is stopped, the fluidity is lost and solidified with time as described above, and the ground injecting material to be injected later pushes the plastic gel formed in advance from the inside to the side, and the upper ground direction. Injected by a method of laterally polymerizing without deviating, and by dehydrating the side ground, dehydration at the external part of the injection site is achieved, and a hardened zone of a hardened plastic gel Is formed, and the plastic gelled material by the ground injection material for post-injection overlaps to increase into a large lump.

  In this case, a predetermined number of holes 4 are formed in a predetermined area of the ground 3 at predetermined intervals in the transverse direction, and injection pipes 9 are inserted into the respective holes separately. The time 5 lag is connected to the injection device via the valve 5 and the pump p, and the injection material to the drilling hole 4 is shifted via the computer by a controller 6 having a computer to shift the injection timing of the ground injection material through the computer. For the holes 4 formed in parallel in the lateral direction, the ground injection material is injected by the interval method at a predetermined time lag through the valve 5 and the controller 6 and the adjacent holes 4 side of the ground. Consolidation dehydration of the entire area can be performed, and as a result, the strength of the entire area can be improved.

  In other words, the improved ground is injected through the injection hole, and if a large amount of the ground injection material is injected into a predetermined region at once, the surrounding soil may be destroyed before the sufficient area is consolidated, or the ground may rise. However, if the total injection volume is divided and press-fitted at intervals, it will be plastic, so the flow will stop due to the interruption of the injection, it will be held in that position, the surrounding soil will be consolidated and dehydrated, and the plastic grout Given the time for dehydration, the size of the solidified body by the bulk plastic gel grows sequentially, and the composite ground with an increased density sandwiched between the columnar solidified body and the columnar solidified body.

  Of course, in this mode, by taking a predetermined interval method, it is possible to return to the initial drilling hole 4 after making a round of all the drilling holes 4 at a predetermined timing. In the injection of the board injection material, the formed mass of the plastic gel is solidified and maintains a compacted state with respect to the ground 3. In other words, the improved ground is injected through the injection hole, and if a large amount of the main ground injection material is pressed into a predetermined area at once, the surrounding soil will be destroyed before the sufficient range is consolidated. When divided and press-fitted at intervals, it is plastic, so the flow stops when the injection is interrupted and is held in that position, and the surrounding soil is given a time for consolidation dewatering and a time for dehydration of the plastic gel. The size of the consolidated body due to the plastic gel grows and becomes a composite ground of a columnar consolidated body and an increased density region sandwiched between the columnar consolidated body.

  For this reason, the injection pressure produces a consolidation action in the lateral direction rather than acting on the ground uplift.

  In addition, due to the function of the plastic gel injected at a predetermined time lag in the axial direction upward of the drilling hole 4, the displacement is more likely to occur in the horizontal direction than in the vertical direction, and therefore, the upward protrusion of the ground 3 can be avoided.

  FIG. 2 (c) shows the reinforcement of the ground when an injection pipe 9 having an injection pipe having a tensile strength (or a reinforcing material obtained by tying the injection pipe with a tensile material) is placed on the ground and a plastic grout is press-fitted. The model is illustrated. As shown in Fig. 2 (c), the soil around the ground is compressed by drilling the ground and embedding the injection tube 9 and pressing the plastic injection material at a predetermined position to form a consolidated body on the surrounding ground. Thus, a large soil anchor is formed by consolidation. The injection pipe 9 having a tensile strength is fixed to the ground by the soil anchor. Even in this state alone, if the ground is displaced, the tensile body is stretched and tensile strength is imparted to the ground.

  2 (a) and 2 (b), when injecting from the injection outer tube through the injection inner tube, the injection outer tube having a plurality of discharge ports in the axial direction is covered with a rubber sleeve over the discharge port. To play a role. An injection inner tube having a single packer or a double packer is inserted into the injection outer tube, and the ground injection material is press-fitted from the lower outer tube discharge port, and then stepped up and pressed to strengthen the ground.

  In this case, the boring operation and the injecting operation for installing the outer injection tube can be performed separately. In addition, the inside of the injection outer tube can be re-bored and re-injected, the injection can be surely performed at every injection depth, and the tensile force of the injection outer tube can be applied to the ground, thereby obtaining a pile effect.

  Moreover, the ground which consists of an alternating layer of sandy soil and clay soil can be improved by using together this invention injection material and solution type | mold injection material. This viscous soil was not able to infiltrate with solution type grout, so suspension type grout with high gel strength was injected into vein, but its effect was uncertain because it could not be injected within the specified range. was. However, the above-mentioned injection tube is used to perform compaction injection with a plastic gel injection material on the impervious soil layer, and the soil layer that can be infiltrated can be improved with a solution-type grout. For example, if the ground injection material is injected after solution type grout is injected, the entire ground can be improved.

  Thus, as described above, in the invention of this application, the main ground injecting material injected into each drilling hole 4 performs a pressure dehydrating action on the side of the ground 3 to prevent upward deviation. Therefore, although it is difficult for the ground to be raised, a level detection method using a level sensor is used as shown in FIG. 3 in order to measure the amount of deformation on the ground surface and between adjacent holes. As shown in FIG. 3, a laser beam sensor 15 is provided to the laser beam generating device 11 via a laser receiving device 12 provided at a position that is affected by the ground surface of the ground or the injection of a building.

  Then, through the receiving device and the computer 17, the injection control device 18 appropriately adjusts the transfer of the injection stage to the injection tube 9 and the injection amount, interval time, specific gravity, etc. of the injection of the ground injection material as shown in the figure. To control. At this time, the receiving device 12 is displaced up and down with respect to the laser beam sensor 15 in which the laser beam generated from the laser beam device 11 is precisely produced, and the uplift of the ground 3 is accurately detected. Then, an injection control device (not shown) is started and stopped via the computer 17, and injection is performed at the optimum timing and amount for the consolidation and dehydration of the side ground of the main ground injection material to be intermittently injected, and the ground uplift is measured. However, the injection is optimally performed such as stopping the injection, adjusting the injection amount, and moving to another injection point.

  As shown in FIG. 3, laser beam is used for measurement detection such as lateral displacement of the compacted body of injection and ground uplift, and precise measurement in mm is required for optical detection. is there.

  Accordingly, the displacement of the drilling hole 4 and the bulge of the ground 3 can be measured accurately over a wide range, and a minute displacement such as the displacement of the ground 3 can be accurately detected and the strength of the ground 3 as designed. Improvements can be made.

  Thus, in the above-described embodiment, it is basically possible to improve the strength of the ground 3 through the consolidation dehydration action on the side ground 3, but the injection site of the ground injection material to the ground 3 is possible. In order to eliminate potential causes such as liquefaction phenomenon, the moisture in the ground 3 may escape to the other and increase the fluidity of other ground 3 parts. In order to forcibly dispose the moisture in the ground 3 that is removed along with the injection, a drain material such as a paper drain or sand drain (through drainage and soil layers with different drainage properties) is provided together with the compaction action. The dehydration action can be performed positively over both.

  FIG. 4 shows a plurality of outer holes in a borehole obtained by bending to the ground to be improved, boring with any combination of flexure and straight line, or horizontal boring from the pile to the foundation of the building. Install an outer pipe with a pipe discharge port, insert the inner pipe into this outer pipe movably, and inject this ground injection material into the ground from the inner pipe and outlet through the outer pipe discharge port As a result, the supporting ground under the existing structure, which is difficult to be injected, can be injected quickly, reliably and economically to prevent subsidence or liquefaction of the ground during an earthquake. Can be prevented.

  FIG. 4A is a basic schematic diagram of the ground treatment to be improved directly under the structure. As shown in FIG. 4 (a), bent from the ground surface near the ground to be improved directly under an immovable structure such as a building, a waste disposal site, a reservoir, a reservoir, or the like, or into the ground Boring holes are formed by combining bending and straight lines. Next, a plastic injection material is press-fitted from an injection tube provided in the borehole.

  FIG. 4B is an example of ground injection below the structure, and a plurality of layers can be laminated and processed in the depth direction below the structure.

  Next, FIG. 5 shows another embodiment in which the invention of this application is to be carried out. FIG. 5 (a) shows a case in which a tubular body such as a casing is provided in the ground and a tensile material such as a reinforcing bar is inserted, the casing is pulled out while being pressed into the ground injection material, and a solid aggregate is formed in the ground. In addition to compressing and strengthening the surrounding ground, it is a mode of aiming for composite ground strengthening with a pile body that also has an effect as a compression pile or tensile pile, and FIG. 5 (b) is a pile foundation by press-fitting a plastic injection material Fig. 5 (c) shows a mode of anchor formation by a plastic injection material on the retaining wall. 5 (b) and FIG. 5 (c) may use the method of FIG. 5 (a), or the effect of the outer tube as a tensile material by injecting from the inner tube using an outer tube having a tensile force. May be given.

  As the injection management method of the present invention, the injection status from the mixing of the ground injection material to the injection into a plurality of injection points in the ground through the injection material feeding system is displayed on the screen, and the injection management is performed by performing batch monitoring.

  FIG. 6 is a flow sheet showing a specific example of the injection management method used in the implementation of the present invention. The centralized management device X1 performs batch monitoring and management of the injection status, and the status is always in the injection monitoring panel X2. Is displayed on the screen.

  FIG. 6 will be described with reference to FIG. 7 showing an operation flowchart of the centralized management apparatus X1. First, an injection specification file is previously set in the central management system X1 according to the injection purpose and injection conditions (system specification setting registration), and then the start switch of the central management device X1 is turned on to start data recording. At this time, the injection monitoring panel X2 is also turned ON by a lamp, and injection data is displayed on the screen. The injection specification file referred to here is the amount of material blended, the specified flow rate of the grout (appropriate flow range), the specified pressure value (appropriate pressure range), the specified injection amount (appropriate integrated injection range), that is, desired The flow characteristics, injection pressure, flow rate (flow rate per unit time and / or integrated flow rate), etc. In the above, an appropriate range of ground uplift may be added.

  In accordance with an instruction from the central control device X1, water and powder material are supplied in a fixed amount to the mixer 27 from the water tank 4 provided with the measuring device 23 and the hopper 25 storing the powder material, respectively, and mixed by stirring. In addition, when adding the gelation accelerator at this time, the gelation accelerator is added from the hopper 26 for storing the gelation accelerator via the measuring device 23.

  The grout sufficiently mixed in the mixer 27 is subjected to flow measurement by a flow characteristic measuring device 28 attached to the mixer 27 or separately provided, and the result is displayed on the injection monitoring board via the central control device X1. The The flow characteristics shown here are determined by the grout flow, slump, gel time, viscosity, shear strength (cone penetration measurement or the like is used), and the like. When the predetermined fluidity is obtained, the blending is completed, and the grout is further fed from the mixer 27 through the conduit 29 to the grout pump 30. In addition, when the predetermined fluidity is not obtained, the material (water, the granular material, or the gelation accelerator) is added again according to the instruction of the central control device X1, and this is the predetermined flow characteristic. Is repeated until is obtained.

  Here, it is also possible to take out the grout directly from the mixer 27, and it is possible to actually confirm the fluidity manually without using the flow characteristic measuring device 28 and the central control device X1.

  The grout is sent to the grout pump 30 and the grout is transferred to the injection process. In response to an instruction from the central control device X1, the valve 5 is opened, and the grout pump 30 pressurizes the grout with a desired pressure. The pressurized grout is injected and press-fitted into the ground 3 through the conduit 29 ′, the injection hose 31 and the injection pipe 9.

  A pressure gauge p0 and a flow meter f0 are attached to the conduit 29 ', and the measured injection pressure and flow rate (flow rate per unit time and / or integrated flow rate) are transmitted to the flow pressure control device 32, and the central control device Managed by X1.

  Injection is interrupted if the injection pressure and flow rate are not a preset pressure regulation value (appropriate pressure range) or prescribed injection amount (appropriate integrated injection amount range), or if the ground uplift is greater than the appropriate range. Or an instruction for adjustment and control is transmitted by the centralized management apparatus. In addition, since the data is always displayed on the injection monitoring board, the injection conditions can be changed or the emergency injection can be stopped according to the injection status.

  An arbitrary flow meter such as a rotary flow meter or an electromagnetic flow meter can be used as the flow meter f0, and an electric signal output in pulses is input to the centralized management device X1 via the flow pressure control device 32. Will be counted. The flow rate and injection pressure per minute are controlled by adjusting the rotational speed of the grout pump 30 according to an instruction from the central control device X1 based on information from the flow meter f0 and / or the pressure gauge p0.

  Further, the central control device X1 controls the flow rate by adjusting the rotational speed of the pump with an inverter.

  Grout pump 30 may be a pump having an inverter or a continuously variable transmission, or a pump having a return device. The inverter and the continuously variable transmission can directly adjust the flow rate and set it to a predetermined pressure value without receiving an instruction from the central control device X1. The return device can also be adjusted directly to return the pressure in the conduit 29 'to maintain the desired pressure. The above adjustment may be performed manually.

  A compressor may be used instead of the grout pump 30. The grout from the mixer 7 is first provided with a pressurized container and filled therein, and then the grout in the pressurized container is pressurized by the operation of the compressor to form a pressurized injection grout.

  A valve 5 is attached to the injection pipe 9, and this valve 5 is automatically opened and closed by an electrical signal from the central control device X1. Using a plurality of injection pipes 9, simultaneous injection from a plurality of injection points 22 in the ground 3, continuous injection, interval injection, or a combination thereof is performed. The valve 5 can be manually closed when the injection is completed.

  After all injections are completed, turning off the start switch of the central management device X1 ends the data recording by the central management device X1.

  The data from blending to injection is sent to the central control device X1, and the injection status is monitored by displaying the screen on the injection monitoring board X2, and the flow characteristics of the grout, the injection pressure of the liquid delivery system, and the flow rate are determined in advance. Inject while maintaining the range and complete, stop, continue or reinject.

  In addition, by installing a gelation promoting material branch valve 34 that is automatically opened and closed in accordance with an instruction from the central management device X1, the mixing time of the gelation accelerator is managed. The time of addition of the gelation accelerator is registered in advance in the system specification settings, mixed in the mixer 27, added before feeding to the grout pump 30, and pumped from the grout pump 30 via the gelation accelerator pump 35. It is also possible to add a gelling accelerator to the finished grout.

  In FIG. 6, the injection method used in the present invention is provided with a flow characteristic measuring device 28, a flow pressure control device 32, a ground (or structure) displacement measuring device, or a valve 5 that can be automatically opened and closed. It is characterized in that it is connected to the management device X1 and the data is displayed on the injection monitoring board X2. The injection monitoring panel X2 includes “hour data” such as the injection date and time, “grout data” such as the blending amount of the material and grout properties, injection block No. “Place data” such as the injection hole number and injection point, and “injection data” such as injection pressure and flow rate (unit time flow rate and integrated flow rate) are displayed. In addition, injection liquid identification data and ground (or structure) displacement data can also be displayed.

  In FIG. 8, for example, the data of the liquid feeding system (40 data in total including flow rate, pressure, integrated flow rate, and maximum pressure) when injecting with 10 liquid feeding systems is displayed on the injection monitoring panel X2 on one screen. Shows the screen. The screen of FIG. 8 will be described in detail as follows.

Upper two screens:
Group 1: No. 1 to No. 5 integrated flow rate, maximum pressure digital display Group 2: No. 6 to No. 10 integrated flow rate, maximum pressure digital display integrated flow rate is an injection amount for 20 minutes. The maximum pressure was displayed every 30 seconds, and the maximum value from 19 minutes 30 seconds to 20 minutes was displayed. If the maximum pressure continues to be higher than the set pressure, it is judged that the injection of the liquid delivery system is finished. Further, when the integrated flow rate reaches the set integrated flow rate, it is determined that the injection of the liquid feeding system is finished.

Lower half 2 screens:
Group 3: Flow and pressure trend display of No. 1 to No. 5 Group 4: Flow and pressure of No. 6 to No. 10 Each left side of the trend display 2 screen is an instant corresponding to the passage of time (t) in each liquid delivery system A chart of flow rate and instantaneous pressure is shown, and the right side shows average instantaneous flow rate (l / min) and average instantaneous pressure (MPa) from 19 minutes 30 seconds to 20 minutes.

  In this manner, as shown in the screen of FIG. Although 1 to 10 liquid feeding states are displayed at the same time, they can be displayed while switching the screen for each liquid feeding system. The set pressure, the actual pressure, the liquid supply flow rate, and the integrated liquid supply flow rate in the flow rate pressure control device 32 may be displayed on the same screen or different screens. Thereby, the relationship between the pressure and the flow rate can be grasped in real time, and the injection can be managed so as to be within a predetermined setting range. Further, in FIG. 8, pressure and flow rate may be displayed instead of the maximum pressure. Further, the central management device X1 can also create forms such as injection specification files, injection result lists, injection charts, daily tables, weekly tables, monthly tables, and analysis data.

  The injection specification file is an operation setting file of the centralized management device X1, and sets the specified pressure value and the specified injection amount for the injection completion condition of the injection liquid feeding system. Each form file is converted and created from the registered flow rate, pressure, integrated flow rate or maximum pressure data and data such as manual input or automatic input of hole numbers. Furthermore, analysis data is converted and created from each form.

  In the screen of the injection monitoring board X2 in FIG. 8, one for each liquid delivery system, for example, for each injection point in the injection hole shown in FIG. , Injection hole No. , And stage no. At the same time, pressure, flow rate, and chart can be displayed.

  Further, from these data, for example, the block No. of FIG. 1, injection hole No. If 3 is displayed, as shown in FIG. 10, the injection pressure P, the flow rate Q, and the integrated flow rate with respect to time t can be displayed for each stage. In addition, by displaying these three-dimensionally as shown in FIG. 11, the allowable injection pressure assumed from the N value and soil cover pressure at each stage, the range, and the allowable injection amount assumed from the target N value are used as a reference. Set. It is possible to predict the ground improvement effect corresponding to the target N value after injection from the injection amount at each injection stage from the N value data before injection in real time. Control the flow rate.

  In this way, liquid feeding is injected with a predetermined flow rate or set pressure of the pressure injection grout, or with a flow rate or pressure within a limit range. As a result, it is possible to reliably and predict the improvement effect. The set pressure and the set injection amount can be corrected in consideration of the test injection data.

  EXAMPLES Hereinafter, although this invention is described concretely based on an Example, this invention is not limited by these Examples.

Materials Used (1) Slag Blast Furnace Slag 4000 Brain Value (2) Cement Portland Cement, Alkaline Hardening Material (3) Bentonite Swelling Level 2.5g / g or more, Thickener and Water Retaining Material (4) Sulfate Band Aluminum Sulfate, Al ₂ O ₃ = 17.2%, Gelling accelerator (5) Foaming agent Special protein, pre-foaming air generating agent, gelling modifier

Formulation Examples 1-9
Slag, cement, and water were mixed together, and bentonite was added, and the mixture was blended so that it became plastic immediately after blending. Table 2 below shows the adjustment conditions and physical property values of the ground injection materials of Formulation Examples 1 to 9 thus obtained. Formulation examples 5, 6, and 7 are examples of the present invention, and formulation examples 1 to 4, 8, and 9 are comparative examples.

  In Table 2, the plasticity retention time refers to the time during which a gel-like shape is retained if it is stationary but is in a state of flowing when force is applied. In the blending examples in Table 2, by adding bentonite to the slag and cement suspension, it becomes plastic immediately after blending. Therefore, there is almost no breathing.

Further, when the ratio of the cured material is large, the plastic holding time is shortened, and such an injection material is further dehydrated in the ground and quickly solidifies, so that a large lump cannot be formed. Even a small amount of the cured material is sufficiently effective, and the strength development is delayed but the strength increases with time. Therefore, the cured material ratio is 0.1 % by weight or more and less than 1% by weight as described above.

[Factors and conditions as plastic gel]
(1) Hardening expression material ratio Alkaline hardening expression material, that is, cement content: cement (hardening expression material) weight / {relative to the content of powder contained in grout, that is, slag and cement, and bentonite. Slag weight + cement weight + bentonite weight} x 100 [%]

  When the ratio of the cured material is increased, the strength development occurs rapidly and the plastic holding time is shortened, or the precipitation and the breathing increase, so that the precipitated material hardly flows and does not easily become a plastic gel. In other words, when the ratio of the hardening developing material is large, it deviates in a vein shape in the ground or affects the expansion of the massive body. In the present invention, the ratio of cured material is 0.1% by weight to less than 1% by weight.

(2) Water powder ratio Water content with respect to the powder in the grout: water weight / {slag weight + cement weight + bentonite weight} × 100 [%]

When this value is small, it tends to be plastic. That is, the time for forming a plastic gel after blending is shortened, and the flow value is decreased. However, if the water powder ratio is too small, workability is impaired, so the range is made 40 to 150% (weight ratio). By using a thickener or a gelation accelerator, the water powder ratio can be increased. In addition, since the properties of the grout differ depending on the mixing conditions, environment, and materials, the measurement of the breathing rate, flow value, and strength described later is important.

(3) Bentonite addition amount Bentonite content with respect to the powder in the grout: Bentonite weight / {slag weight + cement weight + bentonite weight} × 100 [%]

By adding bentonite to a slag or cement suspension, the viscosity in the grout increases and becomes plastic. The fluidity can be easily adjusted by using bentonite. Further, bentonite can increase the viscosity of the grout and suppress the dispersion in water. The amount of bentonite added is 10% by weight or less.

  Moreover, the addition amount can be decreased by using bentonite having a swelling degree of 20 g / g or more and excellent swelling properties.

(4) Amount of sulfate band added Amount of sulfate band added to the powder in the grout: sulfate band weight / {slag weight + cement weight} × 100 [%]

  The sulfuric acid band is a gelation accelerator, and when added to the fluid state of slag and cement, it promotes gelation and accelerates the time to become a plastic gel. However, since the sulfuric acid band also has an effect of reducing the consolidation strength, its addition amount is 2.0% or less, preferably 0.1 to 1.0%.

(5) Foaming agent addition amount Foaming agent addition amount to powder in grout: foaming agent weight / {slag weight + cement weight} × 100 [%]

  The foaming agent is a gelling regulator that reduces the weight of the grout. If the amount of foaming agent added is large, the amount of air generated in the grout increases, so the grout pushes the soil particles in the ground. A lump cannot be formed. Therefore, the amount of foaming agent added is preferably 0.1 to 2.0%.

(6) Gel time Here, it does not mean chemical gelation that is solidified as found in general water glass grout, but after blending, it loses fluidity due to its own weight, and plastic that flows when force is applied. The physical gelation time until it becomes a gel is expressed as gel time. Unlike a grout made from a common water glass, it cannot show a clear gelation time. Therefore, using the flow value by the table flow, when the value became 20 cm or less was regarded as gelation, this was defined as gel time.

(7) Plasticity retention time Asphalt penetration test method Static penetration resistance was measured using a penetration cone with a total mass of 230 g, tip angle of 15 degrees, and 36 mm according to JIS K 2530-1961. When it exceeded MN / m ² , it became a non-plastic gel and was regarded as consolidated or cured, and the time from gelation to consolidation was defined as the plastic retention time.

(8) Breathing rate After blending, mix the grout thoroughly, then place the grout in a 200ml graduated cylinder and seal it statically. After 1 hour, measure the amount of breathing water (superior liquid). Ask. (Breathing water volume / measuring cylinder capacity) x 100 [%]

  Here, the breathing rate after 1 hour is shown. When the blending rate is 10% or more after 1 hour, the injected solution is easily separated and easily injected in the form of veins or cracks. Thereafter, the breathing rate further increases as time elapses. Therefore, the blending rate after 1 hour is preferably 10% or less, preferably within 5%.

(9) Flow value Based on the flow test (JIS R 5201 table flow), the grouting was given 15 drop motions in 15 seconds, and the spread was measured. About 18 to 19 cm is said to be suitable as the plastic grout, but in the present invention, the fluidity due to its own weight disappeared when the flow value became 20 cm or less, and the gel time was used. The flowable injecting material in the present invention is used in such a composition that the water-to-powder ratio is lowered by pressure dehydration by pouring into the ground and the flow reaches 20 cm or less.

  The flow through the cylinder is to measure the spread of the grout when the cylinder is 8 cm high and 8 cm in diameter filled with grout and the cylinder is removed. Since it can be measured more easily than the above table flow, it is often used in the field. However, since it is simple, an artificial error may occur. FIG. 12 shows the approximate relationship between the table flow and the cylinder flow.

(10) Uniaxial compressive strength After blending, a well-mixed grout was packed in a mold having a diameter of 5 cm and a height of 10 cm, cured in a stationary state, and the uniaxial compressive strength was measured after 1 day or 7 days.

  In order to confirm the effect of the formation of the lump by the plastic gel injection material, the soil tank experiment was carried out using a cylindrical soil tank equipped with an internal pressure of 150 cm, a height of 150 cm, a lateral pressure loading device, and a displacement meter. Went. Assuming that the plastic gel was injected at a depth of 3 m in sandy ground with an N value of about 20, the sand tank was filled in the sand tank so that the relative density was 50%, and the upper pressure of 60 kPa was applied. It was loaded. Formulation Example 5 was used as the plastic gel injection material. The injection rate was 5 l / min, press-fitted for 2 minutes, then interrupted for 3 minutes, and 40 liters of plastic gel was injected by an interval method in which press-fitting was repeated again.

  FIG. 13 and FIG. 14 show changes in press-fitting speed and injection amount during press-fitting, and changes in displacement and upper pressure / side pressure. With injection, the injection rate decreased and the lateral pressure increased. The displacement of the ground surface showed a tendency to evolve at the beginning of press-fitting, but it tended to rise from the point when the injection volume exceeded about 20 liters. This is due to the increase in volume of the plastic gel due to the press-fitting and due to dilatancy. The side pressure increased with the press-fitting as the plastic gel pushed the soil particles, but showed a tendency to decrease during the interval when the press-fitting was interrupted. This may be due to earth pressure redistribution during the interval.

  Next, FIG. 15 shows the relationship between the injection amount obtained from the above measurement results, the gap ratio, and the earth pressure coefficient. The gap ratio and earth pressure coefficient were obtained from the following equations.

Pore ratio = {soil particle density × (volume in the earth tank after press-fitting−plastic gel press-fitting volume) / mass of sand used} −1
Earth pressure coefficient = side pressure / top pressure

  The gap ratio decreased with the press-fitting, but increased slightly from the point when the injection volume exceeded 30 liters where the ground surface displacement began to appear. The earth pressure coefficient increased with the press-fitting, and finally reached about 1.7 times the initial value.

  In this way, a lump made of plastic gel was formed in the ground, and further expanded to a columnar improvement body to increase the density of the surrounding ground, compacted, and further imparted high peripheral frictional force with the ground Create a pile and make a strong ground improvement.

It is a model figure of ground reinforcement by press-fitting of plastic gel, (A) is a cross-sectional view of column connection showing the arrangement of consolidated bodies by plastic grout in the area to be improved, (B) and (C) are plan views and plasticity It is injection arrangement | positioning drawing of an injection material. (B) is a square layout, and (C) is a triangular layout. (a) is a cross-sectional view of a state of pull-up injection from the bottom to the top by a rod injection tube of plastic gel drilled adjacent to the ground of a predetermined area, (b) is adjacent to the ground of the predetermined area It is a cross-sectional view showing an example in which an outer injection pipe is installed and a plastic gel is press-fitted from the injection inner pipe, and is a cross-sectional view of a press-fitting mode by an interval method while switching the valve 5 from one pump, (c) is a cross-sectional view showing the effect of reinforcing the injection tube tensile strength by a high density body of solid ground by forming a solidified body with a plastic gel at intervals between predetermined installations of the injection tube having tensile strength. It is. It is a schematic diagram of the displacement measurement aspect in the middle of construction of the ground. (a), (b) is a basic schematic view and a cross-sectional view of the seismic reinforcement injection just under the structure. (a) is a schematic diagram of press-fitting of a plastic gel by inserting a reinforcing bar into a drilled casing and pulling out the casing. Since the plastic gel does not deviate, the surrounding ground is consolidated to form a grout pile having a large strength. . (b) is a cross-sectional view of ground reinforcement of a pile foundation by plastic grout, and (c) is a cross-sectional view of anchor formation by press-fitting of plastic grout in the retaining wall. It is a flow sheet which shows one specific example of the injection | pouring management method until mixing of the material in this invention and injection | pouring of grout. It is the flowchart of the mixing | blending and injection | pouring which operation of a centralized management apparatus and the centralized management system manages. It is an example of the screen display which represented the integrated flow volume and the maximum pressure about 10 liquid feeding systems, and the flow volume and the pressure on the injection | pouring monitoring board using the centralized control apparatus. The four injection block sections No. It is an example of the screen display which expressed 1-4 on the injection | pouring monitoring board. Ground stage No. It is the graph (chart) which represented the flow volume and injection | pouring pressure in 1-3 on an injection | pouring monitoring board. It is an example of a three-dimensional display of the injection amount or the injection pressure. It is a graph showing the relationship between a table flow and the flow by a cylinder. It is the graph showing the relationship at the time of press injection, the press injection speed, and the injection amount. It is the graph showing the relationship at the time of press-fitting, a ground surface displacement, a mounting pressure, and a side pressure. It is a graph showing the relationship between the injection amount, the gap ratio, and the earth pressure coefficient.

Explanation of symbols

3 Ground 4 Drilling hole 5 Valve 6 Controller 7 Computer 8 Casing 9 Injection pipe
10 Rebar
11 Laser beam generator
12 Laser receiver
14 Footing
15 Laser beam sensor
16 Steel pipe injection pipe
17 Computer
18 Injection controller
19 Reinforced support pile
20 Pile foundation
21 Earth retaining wall
22 Injection points
23 Weighing scale
24 water tank
25 Hopper
26 Gelling accelerator hopper
27 Mixer
28 Flow characteristics measuring device
29 conduit
29´ conduit
30 grout pump
31 Injection hose
32 Flow pressure controller
34 Gelation accelerator branch valve
35 Gelling accelerator pump
36 Level sensor X1 Central control device X2 Injection monitoring panel f0 Flow meter p0 Pressure gauge

Claims (3)

A plastic gel injection material is pressed into the ground through an injection hole provided in the ground, and the plastic gel injection material loses fluidity with time or by dehydration and is made of a plastic gel. The soil is pushed to the periphery while forming a plastic gel injection material itself in the ground to form a lump, and the ground improvement method for strengthening the ground, wherein the plastic gel injection material is the following (1 ), (2) and (3), or (4) as an active ingredient, the ratio of cured material is 0.1 wt% or more and less than 1 wt%, and the water powder ratio is 40 wt% or more and 150 wt%. Less than wt% , and the table flow during press-fitting is 12 cm or more and less than 30 cm and / or slump is greater than 5 cm, and / or the flow through the cylinder is greater than 8 cm and less than 28 cm, before or during press-fitting into the ground To a plastic gel Ground reinforcement wherein the grout der is, and the content of bentonite to the powder injection material is 10 wt% or less.
(1) Slag (S material)
(2) Alkaline curing material (C material)
(3) Water (W material)
(4) Gelatinizing material for powdery materials including bentonite (material B)
However, the ratio of hardening expression = C / (S + C + B) × 100 (%), the ratio of water powder = W / (S + C + B) × 100 (%), and S, C, B, and W each represent weight.   The ground reinforcement method according to claim 1, wherein the plastic gel injection material has a plastic holding time of 10 hours or more and less than 35 hours, and a breathing rate of 10% or less.   The alkaline curing agent is made of any one or a plurality of alkali carbonates such as cement, lime, gypsum and sodium bicarbonate, alkali carbonates such as calcium carbonate and magnesium carbonate, and caustic. The ground strengthening method according to 1 or 2.

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