JP5390060B2 - Ground strengthening method - Google Patents

Description

The invention of fly ash ground grout according Porazon reaction between fluidity and calcium-based powdery productive product ground grout that applies a special characteristic of the gelling and this was pressed into the ground of the ground grout It is related to a ground strengthening method that pushes soil particles to the surroundings by expanding the gel to create a massive solid body consisting of gelled material in the ground, thereby strengthening the ground.

  Conventionally, a mortar injection solution containing cement as a main material has a slurry-like fluidity and solidifies by a hydration reaction. Such flowable mortar causes large breathing if the cement content is low, and separates into the ground and settles to solidify. For this reason, it is unsuitable for gap filling.

  On the other hand, in order to reduce the breathing, it is sufficient to increase the cement content. However, in this case, there is a problem that the hardening of the cement is accelerated and the wide area cannot be filled. For this reason, a method has been proposed in which aluminum, water glass, or the like is used as a plastic material for the flowable mortar mainly composed of cement. However, since such plastic grout has high viscosity and poor flowability, the liquid is fed from the mixer. The fluidity is lost in the middle of the pipeline until it is injected into the ground through the pipe and the injection pipe.

  For this reason, recently, a plastic grout has been developed in which a cement-based suspension and a plastic material are separately pumped and merged and injected before the injection pipe, and used as a gap filling or backfill material. Further, a ground strengthening method has been proposed in which the same method is used to press-fit into the ground and compress surrounding soil particles.

  However, in reality, when injected into the ground, moisture and powder separate in the ground and rapidly lose its fluidity due to dehydration and harden rapidly, making it impossible to extend the plastic holding time. As a result, the ground is split into veins and escapes in an unspecified direction, and the ground strengthening effect cannot be obtained.

  In addition, there are problems such as easy leakage from cracks and dispersibility in groundwater even when used for the purpose of filling voids and preventing evacuation of revetments.

  In recent years, plastic grout has been applied as a gap filler such as a backing material for existing tunnels, cavities under foundations, and shield tunnels. There has also been proposed a ground improvement method for strengthening the ground by press-fitting plastic grout into the soft ground.

  The present invention solves the problems of mortar or plastic grout in which plastic material is added to or merged with such conventional cement as a main component by using grout mainly composed of fly ash. . The present inventor, when fly ash mortar is used in the ground injection method, has characteristics that are completely different from conventional cement-based fluid mortar and plastic grout with cement-based fluid mortar plus plasticizer The present invention was completed.

  That is, a method for improving the fluidity by adding fly ash to cement grout has been already known, but a method in which a small amount of cement is added to fly ash as a main material and a ground injection material is injected is used. Absent. According to the present inventor, when fly ash is used as a main material and a calcium-based powdery hardening material such as cement is mixed with the mixture, the mixture itself thickens with the passage of time, and the ratio of hardening developing material and the ratio of the liquid powder are determined. It was found that even if the powder concentration is increased and the viscosity is increased by adjusting, a suspension having excellent fluidity and stable fluidity can be obtained without separation from water and precipitation.

  Furthermore, when this suspension is used for ground injection, the suspension itself exhibits plasticity over time, or exhibits a plastic gel by dehydration in the ground, and is cured from a plastic gel through a non-plastic gel. I understand. Moreover, it has been found that the plastic holding time for producing a plastic gel is extremely long. Therefore, when it is injected into a cavity where water tends to dehydrate, such as a water-permeable ground or an old tunnel, it is rapidly transformed into a plastic gel due to dehydration from the cracks in the concrete, or in soil with low density. When it is press-fitted into, it is dehydrated and transformed into a plastic gel to form a massive solid body, and it is possible to expand the surrounding ground and increase the density. That is, in the state before injection, the ground injection solution that does not exhibit plasticity is injected into the ground, and then injected into the ground to become plastic. Therefore, the mixing operation and liquid feeding of the injection solution are extremely easy. Therefore, it was found that injection by a simple device was possible. As a result, it is excellent in filling property when injected into a large cavity or a long cavity, is excellent in workability, does not produce an unfilled part, and is easy to disperse even in the presence of groundwater, and can achieve uniform consolidation. I understood.

  In addition, it has been found that even in the filling of gaps in aged tunnels, it is difficult to deviate even if there are cracks that are likely to leak from the concrete part. It was also found that by adjusting the water body ratio itself, it becomes a plastic gel, and in the stationary state, it loses the fluidity, and when a force is applied, a characteristic that produces fluidity is obtained. In other words, it was found that a plastic grout was obtained without adding a plasticizer, and a grout having a very long retention time for the plastic gel was obtained. Furthermore, it was found that the gelation time until reaching the plastic gel can be shortened by adding water glass or aluminum salt to the suspension. Especially noteworthy property is that water glass or aluminum salt is added to the above suspension with a mixer to form a plastic gel, and then it can be fed with a pump to obtain sufficient liquid feeding properties. Can be injected inside. That is, it is possible to inject into the ground without using a conventional method in which cement suspension and plastic material are combined and injected using separate pumps.

  For this reason, there is no problem that the liquid mixture B is mixed with the liquid A which is a suspension, so that the mixing ratio of the suspension is thinned and an easily injected dispersion is injected into the ground. In addition, a method is proposed in which B liquid is mixed in a small ratio (for example, 9: 1 or 19: 1, etc.) with cement-based A liquid, but in the case of void filling, pressure is applied to the ground. In this case, it becomes difficult to mix the same ratio using different pumps as the pump pressure increases, and it becomes difficult to inject the plastic grout into the ground reliably. It can be considered that the difference in flow characteristics is essentially different between cement-based grout and fly ash-based grout.

  The reason why the ground injection material of the present invention has characteristics different from those of conventional flowable mortar or plastic grout is that it mixes special properties of fly ash itself with a small amount of calcium-based hardening agent such as cement. In addition, various fluidity can be expressed by adjusting the ratio of cured material, water powder ratio, and gelation modifier ratio with the prescribed composition, and this is injected from the blender through the liquid feed pipe. By injecting into the ground from the hole, it has been found that ideal characteristics corresponding to the purpose of injection are expressed, and the present invention has been completed.

  The plastic injection material refers to an injection material that is formed by mixing a suspension and a plasticizer, exhibits fluidity when pressed, and exhibits non-flowability when stationary. Conventionally, this type of plastic injection material is a combination of cement suspension or cement bentonite suspension with water glass or aluminum salt, or slag with slaked lime added to water glass or aluminum salt. The merged ones are known (see Japanese Patent Application Laid-Open No. 2003-105745), and have been used for filling such as backfill injection and void injection.

About the difference of these characteristics, the following thing was understood.
・ As the mixing ratio of cement amount to fly ash increases, the characteristics as plastic grout deteriorate.
-In a mixture of fly ash and cement, a grout based on cement has a higher viscosity, a faster curing time, a shorter plastic retention time, and a greater breathing than a grout based on fly ash.

  In contrast, when fly ash is used as the main material, the plasticity retention time is long and the breathing is small when the viscosity is low and plasticity is achieved. That is, when it was seen as a fluid grout for cavity injection, it turned out that it was extremely effective to use fly ash as the main material, but when this was pressed into soft ground, a lump gel was formed in the ground. It was found that the ground could be strengthened by making the surroundings dense.

  Moreover, although the above-mentioned known plastic injection material is vaguely plastic, it can be used as backfill injection, but it forms a massive solid body made of gelated material in the ground which is the object of the present invention. It has proved difficult to use for the purpose of compressing. This is because, conventionally, when plastic grout is injected into the ground in order to achieve such a purpose, it becomes split injection in the ground, and it deviates from the injection target unevenly, making it impossible to consolidate in a lump. This is because there is no research that specifically clarifies the flow characteristics of plastic grout and the caking property in the ground, so the development of a practical composition and construction method for plastic injection materials that meet these objectives has been conducted. It wasn't.

  Conventionally, a non-flowable low slump or almost slump-free injection material (mortar) has been used as a method of strengthening the ground by increasing the density by statically injecting the caking material into the ground and pushing the earth and sand around it. ) Is press-fitted into the ground to form a consolidated body in the ground, and a method of consolidation strengthening the ground is known. (Refer to Japanese Patent Laid-Open No. 2002-294686.) Further, a fluid mortar suspension mainly made of cement and a plastic material are pumped together and injected before entering the injection pipe, and a plastic grout is obtained. A method of press-fitting into the ground has also been proposed.

  However, the former of the above known methods requires a large apparatus, and it is impossible to reinforce the construction conditions in which the building is built and the foundation directly under the building from the viewpoint of workability.

On the other hand, the latter method uses a mortar mainly composed of a flowable cement as described above, and plastic materials such as water glass and aluminum salt are respectively transferred by a pump and mixed and mixed by a pipe-shaped mixing device near the inlet. Although it is made into a plastic shape and pressed as it is, it is difficult to form a lump gel in the ground, and if it can not be completely plasticized in the pipe, of course it is lumped in the ground when it becomes plastic It is difficult to form a gel, and it is normal to split and inject out of the ground to deviate into a pulse shape.
JP 2003-105745 A JP 2002-294686A

  As mentioned above, the plastic grout for ground reinforcement needs fluidity in the hose as long as several tens of meters. On the other hand, if it is pressed into the ground, it does not penetrate between the soil particles, and it is outside the specified improvement coverage range. In addition, a gelled material is formed in a lump in a predetermined position without departing from the splitting site, and a gelled material is formed by the injection solution itself as large as possible. It is required to simultaneously satisfy the contradictory characteristics of pushing and forming a large lump gel and increasing the density of the surrounding sediment.

  Therefore, the present invention uses fly ash, which is an industrial by-product, as a main material, and a small amount of cement or calcium-based cured powder such as lime, gypsum, and slag and water are blended at a predetermined ratio, and flow characteristics and consolidation characteristics. It was succeeded in strengthening the ground by press-fitting it into the ground and creating a solid consolidated body with plastic gel in the ground, solving the problems in the above known technology An object of the present invention is to provide a ground injection material and a ground reinforcement method that effectively use the industrial by-product, and an injection management method thereof. Of course, this ground injecting material can be used not only for the press-fitting method but also for filling the gap such as general backfilling injection, anti-sucking injection for revetment.

  The inventor focuses on the use of special characteristics of fly ash to solve the conflicting problems of fluidity and the formation of massive solids due to the gel of the ground injection material in the ground and the growth to a large diameter. did. Because fly ash is fired, it is porous and lightweight, reacts with a small amount of calcium-based curing material, becomes a plasticity by a primary reaction by pozzolanic action, and passes through a plastic gel to a non-plastic gel. Focusing on solidification by secondary reaction by hydration reaction, this characteristic is extremely useful for forming large blocky plastic gel in the ground by using coal ash (fly ash) as the main material. I found it excellent.

  Conventionally, coal ash has been used as an additive to improve fluidity as part of the aggregate of cement grout. However, it has not been used as the main material of the injection solution injected through the injection tube into the ground. Because it was not caustic in itself.

The present inventor pays attention to the following points of coal ash, and finds that excellent characteristics are expressed by inserting it into the ground through the injection pipe as the main material of the ground injecting material used for the above purpose. It was.

1) Since the main component is calcined silica, the unit volume weight is light, the surface is activated, and the reactivity with Ca is excellent.

2) Fly ash is not self-hardening by itself, but hardens by adding a small amount of cement and mixing it with an appropriate amount of water. For example, fly ash mortar becomes a hardened body even if the amount of cement added to fly ash is a very small amount with a hardening developing material ratio of 10% by weight or less.

3) Fly ash is in the form of spherical particles. When it is made into mortar, it becomes a material with extremely good fluidity due to the bearing effect. In addition, the mixing of the kneaded water contained between the spherical particles increases the binding force in a state close to capillary action, making it difficult to separate and for a viscous material.

4) Since it has the above characteristics, it reacts with a small amount of Ca composition such as cement and lime, and adsorbs Ca to the surface at an early stage to cause an electrochemical reaction, which is itself a self-hardening plastic suspension. It has been found that it becomes a turbid liquid to form a plastic gel and further solidifies via a non-plastic gel.

5) On the other hand, the mixture of fly ash and cement is very sensitive to water because the slump and flow values change greatly due to a slight difference in the water powder ratio, and management of the water powder ratio is important. It will be something. When there is little water, fluidity | liquidity will lose | eliminate, and when there is too much water, it will be in a slurry state and the coupling | bonding of particle | grains will become inadequate.

6) Furthermore, the ground injection is controlled by adjusting the ratio of the powdered body consisting of fly ash, which is a non-self-hardening powdery material, and powdered calcium-based hardened material, and the ratio of hardened material in the whole powder. Adjust the flow characteristics of the material in the ground and the expansion of the gelled material in the ground, and further adjust the gelation time until reaching the gel with an accelerator or retarder to improve workability and the gel in the ground. It turned out to adjust the size.

7) The properties of fly ash vary greatly depending on the coal ash production area and the combustion state at the power plant. Variations in properties change the specific gravity, unit weight, properties with respect to the water body ratio, and the like. Furthermore, the fluidity varies with time during the process of feeding the injected liquid and the process of injecting the injected ground. The liquid mixture makes it difficult to adjust the composition and control the injection. For this reason, not only the setting of the blending range but also the blending management system and the injection management system are important.

8) The unit volume weight is as small as 1.7 tf / m ² degrees, and the effective weight decreases especially when injected under the groundwater surface, which is effective for reducing the amount of ground subsidence and earth pressure.

9) The fly ash particle size distribution is mostly 100 microns or less, and the fly ash mortar of the present invention becomes a dense hardened body, so its own water permeability coefficient is on the order of 10 ⁻⁷ cm / sec. The injected solidified structures are made continuous to form a uniform water-impervious structure.

10) Aging deterioration is very small, and the fly ash mortar of the present invention satisfies the environmental standards in the water quality test and the dissolution test results. Moreover, even if it is injected into a cavity in the ground under ground water, the turbidity is partially concentrated and difficult to diffuse. The well-kneaded fly ash mortar injection solution of the present invention has little breathing and almost no volume change of the solidified body, and the boundary surface between the injected solidified bodies is united to fill the cavity without gaps. By adding a gelation accelerator, a plastic gel that can immediately stand in water is formed.

11) Due to “hydrophilicity” which is the nature of fly ash, it is difficult to become familiar with water, and it takes a long time to mix with mixed water until the flow and slump are stabilized. While general concrete kneading time is less than 1 minute, fly ash mortar requires more than 3 minutes. For this reason, a sufficient kneading device and a pressure feeding device are important. Alternatively, fly ash and cement may be mixed in a predetermined ratio as powder and then kneaded with mixed water. In this case, fly ash and cement may be kneaded while being metered by a continuous meter provided for each belt conveyor, and further kneaded by a patch mixer.

12) The workability suitable for kneading and pumping fly ash mortar is most preferably around 25 cm by table flow and around 20 cm slump. The determination of the amount of kneading water that governs slump and flow greatly affects workability. It is important to accurately determine the fluidity that changes sequentially with time and to quickly adjust the blending ratio and the water content ratio in order to form a massive plastic gel in the ground. By controlling the water powder ratio and the hardening material ratio by the flow, it is possible to grow the plastic gel in the ground.

13) As described above, when a gelling accelerator is added to fly ash cement, the gel time for forming a plastic gel according to the amount added can be adjusted. By adding fly ash mortar with water glass or aluminum sulfate as a promoter, slump is easily reduced from about 20 cm to 10 cm or less to form a plastic gel with dehydration in the ground, and the gel retains its plastic shape. By continuing the press-fitting from a long time, a lump gel grows to form a large lump gelled product in the ground, and further changes to a hardened body via a non-plastic gel with the passage of time or dehydration. Such characteristics are due to the fact that most of the active ingredients of fly ash mortar are fly ash, and the characteristics of fly ash appear greatly because only a small amount of cement is required. In other words, because fly ash is spherical, it has excellent fluidity due to bearing action and viscosity that is difficult to separate due to the binding force of kneaded water that is close to capillary action, and it is difficult to separate with water due to water repellency, making a lump gelled product It seems to enable the phenomenon that gelled material grows greatly.

14) In the above, further aggregate can be added. 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.

15) Immediately after adding an aluminum salt such as aluminum sulfate or water glass (including an acidic water glass obtained by mixing water glass and acid) to fly ash mortar. Flow and slump are greatly reduced. It is thought that aluminum sulfate reacts with calcium hydroxide in fly ash mortar to produce an ethrin guide. Due to the formation of etrin guide and hydrated compound and the consumption of crystal water accompanying it, the viscosity of fly ash mortar immediately increases and fluidity decreases.

(Al ₂ (SO ₄ ) ₃ · 18H ₂ O / sulfuric acid sardine) + (6Ca (OH) ₂ / calcium hydroxide) +
8H ₂ O
→ 3CaO · 3CaSO ₄ · Al ₂ O ₃ · 32H ₂ O / Etrin guide

  Addition of sulfate to fly ash mortar results in a decrease in slump, a decrease in flow and an increase in viscosity with stirring for 1-2 minutes. In order for the fly ash mortar to form a plastic gel in the ground without splitting into veins and the bulk gel to grow large, the hard ash mortar expression ratio, water body ratio, aluminum ratio, flow value, slump The conditions for the plastic injection material, such as the range of values, and the injection method are important.

The relationship between the composition of the fly ash mortar ratio and the flow characteristics in the present invention is as follows.
Cured material ratio C / F + C × 100 (%): 1% by weight or more and less than 50% by weight
Preferably 1 to 40% by weight
More preferably 1 to 20% by weight
Water powder ratio W / F + C × 100 (%): 20 to 150% by weight
Aluminum ratio Aluminum / F + C × 100: 0 to 2.0% by weight
Water glass: 0 to 7.0% by weight in silica content
Slump (cm): 26 cm or less
Preferably about 4-26cm
Flow (cm): Less than 30 cm
Preferably about 13-28cm

16) The biggest problem in press-fitting plastic grout into the ground is that the cemented suspension grout has a high viscosity, but if it is made plastic, the inlet of the injection pipe that opens into the ground There is a problem that the resistance to press-fitting from the liquid and the liquid feeding resistance of the liquid feeding pipe up to the injection port are extremely large and are easily clogged in the liquid feeding pipe and the pump. For this reason, there was a concern that if a thin blend was used to facilitate liquid feeding, the veins would form in the ground. For this reason, in the prior application technique, a cement-based suspension with good fluidity and a plastic material are mixed at the time before being sent to the injection pipe in the same manner as in the backfilling injection, and instantly turned into a plastic gel. A method of press-fitting into was proposed. However, it is difficult for high-strength, fast-setting cementitious plastic plastic gel that has become a plastic gel in the injection tube to grow into a large block gel in the ground, and requires a large injection pressure. To do.

  The present inventor has improved the ground by compressing the surrounding earth and sand by injecting into the ground to form a large gel, compared to the injection in which the injection of plastic grout for backfilling and filling of voids requires almost no injection pressure. We focused on the completely different things in the injection. This is because, in the case of press-fitting, a dehydration phenomenon occurs, so if it is left on the ground part, even if it is a compounded liquid that does not exhibit plasticity, it will exhibit plasticity, but it will take a long time to exhibit plasticity (gelation time) Is long). The suspension compound liquid is liquid A, the plastic material is liquid B, and when it is merged into the injection tube, the water body ratio rapidly changes in the process of dehydration that occurs at the same time as it is injected into the ground even if it does not become plastic. It has been found that the plastic grout is reduced and the plastic gel grows large and solidifies through the non-plastic gel.

  In particular, it has been found that such a phenomenon becomes very remarkable in the present invention mainly composed of fly ash and having a small ratio of cured material. This is probably due to the fluidity of the fly ash described above.

As a result, resistance pressure in the liquid feeding pipe during liquid feeding and clogging in the pump no longer occur.
That is, although it is a non-plastic grout when it is injected into the ground from the discharge port of the injection tube, it rapidly becomes a plastic gel in the process of permeating into the ground, and the gel is held while holding the plastic gel. It will be expanded.

  That is, as shown in Table 1, the blending times 1 and 2 require 480 minutes or 300 minutes for the gelation time to become a plastic gel in the above-ground part (until the injection pipe discharge port). However, in the ground, as the water body ratio decreases from 35% to 30% to 25% due to dehydration, it decreases to 0.1 minutes, and the plastic holding time is 7.5 hours, so that the breathing is small and the viscosity is increased. As a result, it becomes difficult to diffuse and the solidified product has high strength. Such characteristics are the flow characteristics of the injection material of the present invention, which has not been known so far.

  Therefore, although it does not exhibit plasticity at the time of injection, it becomes plastic only after dehydration in the ground. In the injection of the plastic grout, even if the compounding liquid is injected as it is, the suspension can be applied as liquid A and the gelation promoting material can be injected as liquid B, regardless of the means. Moreover, the plastic gel can be formed in the ground without using a blending device or the like in the injection tube due to the reactivity of fly ash.

17) While fly ash mortar has fluidity, it exhibits characteristics that the reaction changes with time in the process of maintaining fluidity due to excellent reactivity. The present inventor has completed the present invention by using this change in characteristics over time to clear the contradictory conditions for adapting to the purpose of the plastic injection material described above.

  As a result of the following studies by the present inventors, a ground improvement method that can be designed by increasing the strength by pressing a ground injection material to form a large gelled material in the ground and making it possible to design can be realized.

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 the density of the ground between the injection holes around the massive consolidated body is reduced only after the formation of a massive solidified body by gelled material within the receiving area of each injection hole. This is because an increase can be expected with certainty.

2. The material injected into the ground is prevented from penetrating and solidifying between the soil particles, so that the soil particles on the ground between the plurality of injection holes are pushed away by the massive gelled product. 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.

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 pipe allows the workability to apply this technology to seismic reinforcement of ground with dense buildings.

6). Make it applicable not only to sandy ground but also to viscous ground.
In the route that is injected into the ground via the liquid feeding pipe and the injection pipe line from the infusion solution blending system, while maintaining fluidity (Requirement 5), 1, 2, 3, 4 above after being injected into the ground Allows for the requirements of

  In order to cause such a process to occur between soil particles in the ground by means of injection, it is impossible with cement-based mortar, and a small amount of the hardening-expressing material is mixed into the incinerated fly ash. Only possible.

  In order to shorten the time until the plastic gel is exhibited, it can be adjusted by adding water glass or aluminum salt. That is, they act as gelation accelerators. When acidic water glass is used in which water glass and an acid such as sulfuric acid are mixed to remove alkali from the water glass, a gel is formed almost instantaneously. In the present invention, acidic water glass is also treated as water glass. In this case, the gelation time can be adjusted by using sodium bicarbonate or sodium carbonate in combination. A gel retarder such as lignin sulfonate can also be used.

  Even when the injection material is not plasticized at the time when it is press-fitted into the injection ground by a pump, it becomes a plastic gel easily by pressure dehydration in the ground. In addition, if a self-hardening plastic suspension that exhibits plasticity itself, which loses its fluidity when mixed at rest, is kneaded with a mixer, etc., fluidized and pressed into the ground, a slight amount of injection pressure is generated in the ground. Dehydration reduces the liquid mass ratio of the suspension and loses the fluidity, and the plastic grout that is fed one after the other presses and compresses the surrounding ground by pressing and compressing the gelled material that has lost the fluidity by injection pressure. The volume of the massive solid body is expanded and finally reaches a strength that cannot be expanded by the injection pressure. A solid body composed of a gel is formed and finally hardened by a hydration reaction.

  As a result, the solidified body formed in the ground does not penetrate between the soil grains, nor does it penetrate into the veins, and a solidified body is formed by the gelled product compressed by the injection pressure. It can be said that the ground improvement with high density and reliability can be achieved as a result of the corresponding interval between the soil particles being reduced. Even if there are more aggregates than cement, such a phenomenon tends to split into veins as long as the cement is the main material of the hardening developing material.

  On the other hand, the advantage of plastic grout with fly ash as the main material is that it has a large flow before being injected into the ground or in the ground after injection, that is, a composition having fluidity of 20 cm to less than 30 cm and slump exhibiting 15 to 26 cm. Even if it is used, it is dehydrated by press-fitting into the ground, and even if the flow is 30 cm or more before injection or the slump is 26 cm or more, it becomes a plastic gel in the ground and has a sufficient plastic holding time. In that it can grow into a sufficiently large lump gel.

  As a result, a self-hardening suspension produced using fly ash as the main material is pumped into the ground with a pump, thereby causing phenomena 1, 2, 3, 4, and 5 in the ground. Has been successfully consolidated.

  In addition, the present inventor, when injecting a plastic gel having a small flow and slump and having a low fluidity, is pumped with a pump after blending with a mixer. Further, by feeding the liquid from the mixer to the pump via a snake pump or a liquid feeding device having a rotating shaft having spiral wings, it is possible to easily feed a highly viscous plastic grout. According to this method, it was found that even a highly viscous plastic gel of 1000 cps or more can be pumped.

Speaking of typical examples of the plastic injection material of the present invention, a powdery hardening material composed of cement or slaked lime added to the fly ash of the powder that is the main material constituting the suspension is contained in the granular material used. It is less than 50% by weight, preferably 1 to 40% by weight, more preferably 1 to 20% by weight, and the water powder ratio is 20 to 150% by weight, preferably 20 to 80% by weight. In the case of adding the gelation accelerator, the powder is mixed in the injection material, that is, 0.01 to 0.35% in terms of aluminum salt Al ₂ O _{3 with} respect to the total amount of the main material and the hardening developing material, and the flow is performed. 13 to 28 cm (If dehydrated in the ground, a plastic gel is formed in the ground even if it is 28 cm or more before injection), preferably 15 to 25 cm, gel time is within 3 minutes to several hundred minutes, plastic state retention time is several 10 hours or more from the time, breathing rate is within 5%, slump is 26cm or less (if dehydrated in the ground, slump will become a plastic gel in the ground even if the slump is 26cm or more before injection), preferably 25-5cm plastic injection It becomes with material.

Due to these characteristics of the present invention, addition of silica such as water glass or acidic water glass as a gelation accelerator can greatly reduce gel time and plastic holding time, and also breathing and slumping. Furthermore, the flow becomes smaller. The ground injection material of the present invention is pressed into the ground to become a plastic gel, pushes the soil particles to the periphery, grows into large aggregates in the ground, and can strengthen the ground.

  The present invention relates to a ground injection material that applies the special properties of plastic gel by the polazone reaction between the fluidity of fly ash and the calcium-based powdered cured product, and press-fitting this into the ground to expand the soil by expanding the plastic gel. The particles are pushed to the periphery, and a massive solid body made of gelled material is created in the ground to strengthen the ground.

  As described above, the present invention uses a suspension that exhibits plasticity itself by adding a smaller amount of calcium-based hardening agent to fly ash, but is blended with the type and combination of the granular material to be used and a specific blending ratio. Therefore, a desired plastic injection material that exhibits flow characteristics and consolidation characteristics according to the purpose is obtained, and this injection material is pressed into the ground to form a massive solid body in the ground. The soil particles in the ground surrounded by the hole can be applied to the surrounding area to strengthen the ground.

  The massive solidified substance in the ground is a ground injection material that forms a plastic gel that can move by pressurization but does not penetrate between soil particles and does not split into veins. When expressed, it is preferably a ground injection solution that forms a plastic gel in the ground or in the state before injection, preferably in the range of 13 to 28 cm, preferably 15 to 25 cm, and slump in the range of 26 cm or less, preferably 4 to 26 cm. Further, as described above, by dehydrating in the ground, a plastic gel is formed in the ground even when the flow is 28 cm or more and the slump is 26 cm or more before the injection.

  If the flow value or slump is less than this, it will be difficult to grow a solid aggregate of plastic gel in the ground, but if there are large voids or the ground is extremely soft, the gelation The flow and slump can be applied by increasing the amount and reducing the amount.

  As described above, the present invention mixes fly ash with a powder material of hardening-expressing material and water at a specific ratio, but fly ash (F material) and a hardening-expressing material that is a calcium-based powder include cement, lime, gypsum, Either slag or a plurality of groups (C material) and water (W material) are mixed.

Incidentally, the slag may be a conventional 4000 (cm ² / g) Blaine such general products in the above, 15000 (cm ² / g) or ultra fine slag such Blaine. The ratio of the cured material is less than 50% by weight, preferably 1 to 40% by weight, more preferably 1 to 20% by weight, and even 1 to 10% by weight has a very excellent effect. The water powder ratio is 20 to 150%, preferably 20 to 60%. Here, the cured material ratio is C / (F + C) × 100, the water powder ratio is W / (F + C) × 100, and F, C, and W are weights, respectively.

  If such a liquid mixture is mixed, it remains as it is when the water powder ratio is small, and when the water powder ratio is large, it becomes a plastic gel with a flow of 15 to 25 cm sooner or later by dehydrating in the ground. The plastic gel flows when force is applied, but stops flowing when it stops. Therefore, by dehydrating under pressure in the ground, a plastic gel having a flow value in the above range is formed in the ground even when the water powder ratio is large.

  The plastic gel formed in the ground needs to be expanded as widely as possible to form a large aggregated solid while having a low fluidity. For this purpose, not only the water powder ratio is important, but also the ratio of the cured material is important.

  If the ratio of cured material is excessive, the characteristics of the mortar grout made mainly of cement, etc. will be strong, the water will separate, the breathing will increase, and it will be difficult to become a plastic gel. It becomes a gel and solidifies in a short time to form a high strength consolidated body. For this reason, it splits and deviates or solidifies and becomes impossible to inject. That is, because the main material is fly ash, the ratio of cured material is less than 50%, preferably 1 to 40%, more preferably 1 to 20%, most preferably 1 to 15%, A massive solidified material that has grown greatly through the plastic gel in the ground is formed.

Furthermore, the present invention relates to aluminum sulfate in order to adjust the time during which a self-hardening suspension composed of fly ash, one or a plurality of cement, lime, slag as a hardening developing material and water develops plasticity. Or an aluminum salt such as polyaluminum chloride. In this case, it is preferable that the ratio of the cured material is 2 wt% or more and less than 50 wt%, the water powder ratio is 20 to 60 wt%, and the aluminum ratio is 2.0 wt% or less, preferably 0.1 to 1.0 wt%. The blended grout is 0.01 to 0.35% by weight in terms of Al ₂ O ₃ . Here, the aluminum ratio is aluminum material / (F + C) × 100. Aluminum material represents weight.

In the above, the aluminum salt or water glass as a gelation accelerator may be mixed with fly ash or hardening material and press-fitted into the ground with a pump, or may be joined in or near the injection pipe. They may be mixed, or in the process of injecting a mixed solution of fly ash, a curing agent and a gelation accelerator, a gelation accelerator may be further mixed and injected.

  Furthermore, the present invention mixes fly ash as the main material of the granular material, gypsum, gypsum, cement, lime, slag, or a group (G) of a plurality of groups (G) and water (W) as the hardening material. . The gypsum ratio and the mixture of gypsum is 1 to 40% by weight, preferably 1 to 20% by weight, and the water powder ratio is 20 to 70% by weight. Here, the gypsum ratio and the mixture ratio of gypsum are G / (F + G) × 100, and the water powder ratio is W / (F + G) × 100. G represents weight.

  Furthermore, the present invention includes fly ash as the main material of the granular material, cement, lime, gypsum, slag or a group of plural as the hardening developing material, in addition to water, incineration ash, clay, on-site generated soil It is also possible to mix silica sand. The plastic injection material of the present invention can be reduced in weight by adding a foaming agent or a foaming agent. In the above, by adding bentonite and further polymer thickeners such as polyvinyl alcohol, carboxymethylcellulose (CMC), methylcellulose, etc. as clay, water dispersibility is suppressed, precipitation is reduced, and workability is improved. effective.

  Moreover, when the ground injection material of the present invention includes any one of incineration ash, clay, on-site generated soil, and silica sand, the ratio of cured material is 1% by weight or more and less than 50% by weight, and the water powder ratio is 20 to 150. %. Here, the water body ratio = W / F + C + B × 100 (%), where B is the weight of any one of incinerated ash, clay, on-site generated soil, and silica sand, or a plurality of these. .

  The present invention is a static plastic gel press-in method, which does not generate vibrations in a large machine like a sand compaction method, and has a special equipment for mortar that does not flow like a low slump mortar press-in method No large equipment is required unlike the press-fitting method. This is due to the excellent workability due to the fluidity of fly ash. For this reason, the construction method of the present invention can be said to be a construction method with excellent workability with no pollution because it can be easily constructed even in a narrow work area with no noise and no noise using a simple apparatus used for the normal injection hole method. . The construction method of the present invention will be described below.

  The above-mentioned plastic injection material according to the present invention is suitable for filling the gap of the old tunnel, filling the back of the shield tunnel, filling the gap of the foundation, filling the gap of the revetment back through the injection pipe inserted into the ground. However, it is suitable for the restoration injection method of buildings that have been pressed into the ground and pushed into the surrounding area, solidified into a lump while pushing the surrounding earth and strengthened, or submerged on the same principle. When injecting such a ground injection material, the initial injection pressure is lowered to increase the injection pressure stepwise while dehydrating the preceding injection, or injection is performed while intermittently pressurizing by repeating injection and interruption. Thus, the gelled product exhibiting plasticity may be consolidated while increasing the density of the ground by spreading the soil particles to the periphery while preventing the penetration due to the penetration between the soil particles and the splitting of the ground.

  In addition, this injection is performed by simultaneous injection from a plurality of injection points, switching injection to another injection point, that is, continuous injection as shown in FIG. 2B, and shifting from one injection point to another injection point. An interval injection method in which injection is performed and then returned again and repeatedly injected, or a combination of these methods is performed.

  Furthermore, the ground injection material according to the present invention is injected from a plurality of injection points to restrain the ground between the injection points, or a plurality of injection pipes are installed on the ground at intervals of 0.5 m or more and 3 m or less. The ground density can be increased and the ground can be consolidated. In addition, when injecting the injection material of the present invention 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 ground injecting material injected into the ground Injection can be performed while promoting dehydration or ground dehydration.

The above-described injection is performed using, for example, the following injection tubes shown in (a), (b), and (c).
(A) An injection tube having 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) A multi-pipe having at least one bag packer is used for the outer tube, and the inner tube is injected through the outer tube.

  In order to significantly improve the strength of soft ground, etc., if an excessive amount of ground injection material is injected at a time, the surface of the ground will rise, or the ground will be destroyed in the lateral direction. Although the strength does not improve as set, it takes advantage of the characteristics of the ground injection material, and it has fluidity during the injection. When the injection is stopped, the fluidity stops and gelation or pressure dehydration occurs. Since the gel state appears, it is repeatedly injected into the target injection soil layer by a small interval method (injecting at intervals of time) to make it quasi-solidify, compacting without destroying the injected ground, The excluded water is dispersed between the surrounding soil particles, compacted and dewatered to the side of the ground, and the consolidation diameter by the gelled product is increased, or these grouts are injected with a certain time lag (time difference).

  For example, in the case of the vertical injection, the injection is repeated by the interval method, and the ground is split by press-fitting the plastic grout repeatedly into the plastic grout previously injected. Instead, the suspension type 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 ground injection material of each drilling hole is injected into each soil layer or each stage by an interval method with a predetermined time lag, and the plastic grout injected in advance consolidates the surrounding ground, or by itself In addition, when the injection solution is dehydrated, by repeatedly injecting repeatedly, the plastic grout to be injected into the predetermined number of holes is for each soil layer or each stage with respect to the ground of each hole, 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. The ground surface is improved without deviating from the ground injection material, and the ground injection material is press-fitted from below the bag body, so that the ground injection material does not get over the hardened body of the bag and restrained by the bag body. Due to the effect, 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 be within a depth close to the ground surface, for example, within a range of 3 m. This is because even in the case of ground injection material, 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 a depth of 3 m, if a large amount of injection is performed from one injection hole, the soil cover is small and the ground surface is likely to deviate and the ground is likely to rise. 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. Also, in the area close to the ground surface, the injection step is shifted from the top to the bottom, the plastic 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 upwards and injecting, ground uplift on the ground surface can be reduced, or the upper constraining effect allows reliable improvements below it.

  Furthermore, in order to eliminate soil moisture in the injection of the ground injection material to the ground, a drain material for drainage is also provided, and intermittent drainage effect (injection is interrupted). It is possible to promote the side consolidation dehydration effect of the ground by dehydrating during the operation) or to accelerate the dehydration of the ground injection material (the application of this drain material is suitable for strengthening the ground of the cohesive soil layer) . Alternatively, drainage pipes are installed to remove groundwater and increase the speed of consolidation.

  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. In general, the injection of the ground injection material is adjusted, or the injection amount and the injection depth are changed via the control device of the injection device, or the specific gravity of the injection solution, the injection amount, the interval time, etc. are automatically set. By switching and adjusting and moving to another stage before exceeding the predetermined displacement, the ground strength can be reliably improved by compaction dehydration as designed, and the above ground displacement measurement is the ground uplift on the ground surface In addition to the above measurement, you can set a measuring rod with a strain gauge in the ground to know the change of the ground part in the measuring direction, and install a pore water pressure gauge in the ground to check the consolidation dehydration status. I can grasp it.

  FIG. 1 shows an injection arrangement of ground injection material. In this invention, when a suspension-type ground injection material is pressed into a soft ground at a low speed from an injection tube, while the injection pressure is being applied, the plastic gel exhibiting fluidity expands the range of the bulk gel. In the advanced part of the grout, the water content of the grout is reduced by dehydration to the surrounding soil particles due to the injection pressure, and the fluidity is lost, resulting in an unplasticized 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, the embodiment of the present invention to be implemented will be described as an embodiment of the present invention with reference to FIG. In this case, as shown in FIG. 2A, the rod injection tube 9 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 possible to expand the gelled product by moving the stage so that the discharge port is located in the range before the gel of the ground injection material injected into the ground is in the state before becoming the non-plastic gel. This is preferable.

  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 the suspension-type ground injection material of the present invention is suspended from the injection apparatus (not shown) on the ground by an interval method at a predetermined time lag. The injection is carried out in series while being converted into a predetermined stage, 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, plastic grout in each cycle is injected at a low pressure so as not to deviate in the initial stage of injection, and is injected while draining the ground 3 or dehydrating the injected liquid, and at a predetermined timing. After that, 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 grout previously injected sideways from the inside to the upper ground direction. Injected in a laterally overlapping manner without deviating, the side ground is consolidated and dehydrated, and the dehydration at the injection site is achieved, increasing the strength of the ground injection material gel and ground However, the ground injection material for post-injection will improve with each cycle.

  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. At a time lag, the valve 5 and the pump p are connected to the injection device, and the plastic grout is shifted by the controller 6 having the computer 7 through a predetermined program and the injection timing for the drilling hole 4 is shifted via the computer 7. The side ground of the adjacent drilling holes 4 by injecting plastic grout into the drilling holes 4 formed in parallel in the lateral direction through a valve 5 and a controller 6 at a predetermined time lag by an interval method. As a result, the strength of the ground can be improved over the entire area.

  In other words, the improved ground is injected through the injection hole, and if a large amount of ground injection material is injected into a predetermined area at once, the surrounding soil will be destroyed before the sufficient area is consolidated, or the ground will rise. However, if the total injection volume is divided and press-fitted at intervals, it will be plastic, so the flow will stop when the injection is interrupted, it will be held in that position, the surrounding soil will be consolidated and dehydrated, and the ground injection material will be dehydrated. Thus, the size of the solidified body by the lump gel is gradually grown, and the columnar solidified body and the composite ground having an increased density sandwiched between the columnar solidified bodies are obtained.

  Of course, in this aspect, 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 injection material, the injected plastic grout 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 ground injection material is injected into a predetermined area at once, the surrounding soil will be destroyed before the sufficient range is consolidated, but the total injection amount is divided. However, when it is pressed in at intervals, it is plastic, so the flow stops when the injection is interrupted and is held at that position, and the surrounding soil is given a time for consolidation dewatering and a time for dehydration of the ground injection material. The size of the consolidated body due to the gel grows and becomes a composite ground of the 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 ground injection material that is 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.

  FIG. 2C illustrates a ground reinforcement model in the case where an injection pipe 9 having tensile strength (or a reinforcing material obtained by tying a tensile material to the injection pipe) may be installed on the ground and a plastic grout is press-fitted. . As shown in Fig. 2 (c), the surrounding soil is compressed by drilling the ground and burying the injection pipe 9 and press-fitting the ground 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 on the discharge port. To play a role. An injection inner pipe having a single packer or a double packer is inserted into the injection outer pipe, and a ground injection material is press-fitted from the lower outer pipe discharge port, and then stepped up and press-fitted to strengthen the ground.

In this case, the boring operation and the injecting operation for installing the outer injection tube can be performed separately. Moreover, the inside of the injection outer tube can be re-bored and re-injected, and 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, and the pile effect can be obtained.

  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. Since this clay soil cannot be osmotically injected with a solution-type grout, a suspension-type grout with a high gel strength was injected into a vein, but its effect is uncertain because it cannot be injected within a predetermined range. was. However, it is possible to improve the soil layer which can be infiltrated by a solution type grout by using the above-mentioned injection tube to perform the consolidation injection with the soil injecting material to the soil layer which cannot penetrate. For example, if a plastic grout 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 ground injection material injected into each drilling hole 4 performs the pressure dehydrating action on the side of the ground 3 and the upward deviation is prevented. 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 adjusts the injection stage shift with respect to the injection tube 9, the injection amount of the ground injection material, the interval time, the specific gravity and the like as shown in the figure. Try 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 consolidation dehydration of the side ground of the ground injection material to be intermittently injected, and the rise of the ground 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 in the injection site of the ground injection material to the ground 3. In order to eliminate potential causes such as liquefaction phenomenon, the water in 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 excluded along with drainage materials such as paper drains and sand drains (through the different formations with different drainage and soil properties), compaction and dehydration Can be carried out actively 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. An outer pipe having a pipe discharge port is installed, and the inner pipe is movably inserted into the outer pipe, so that the ground injection material is injected into the ground from the inner pipe and the outlet through the outer pipe discharge port. This shows the mode, so that the supporting ground under the existing structure where it is difficult to inject ground can be injected quickly, reliably and economically to prevent land subsidence and ground liquefaction in the event of an earthquake. I can do it.

  FIG. 4A is a basic schematic diagram of the ground treatment to be improved directly under the structure 10. As shown in FIG. 4 (a), bent from the ground surface near the ground to be improved directly under the immovable structure 10, such as a building, a waste disposal site, a reservoir, a reservoir, etc., into the ground, Alternatively, a boring hole is 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 10, and a plurality of layers can be laminated in the depth direction below the structure.

  Next, FIG. 5 shows a mode of another embodiment of the invention of this application. 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, and the casing is pulled out while being pressed into a plastic injection material, thereby forming a massive solid body in the ground. In addition to compressing and strengthening the surrounding ground, it is an aspect of a composite ground reinforcement with a pile body that also has an effect as a compression pile or a tensile pile, and FIG. FIG. 5C shows a form of anchor formation by a plastic injection material on the retaining wall. 5 (a) and 5 (c) may use the method shown in FIG. 5 (a), and the outer tube having the tensile force may be used to inject from the inner tube to obtain the effect of the outer tube as a tensile material. It may be given.

  As the injection management method of the present invention, the injection status from injection material mixing to injection into a plurality of injection points in the ground through the injection material feeding system is displayed on the screen, and 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 powdered raw materials are quantitatively supplied to a mixer 27 from a water tank 24 provided with a measuring device 23 and a hopper 25 for storing the powdered raw materials, and are stirred and mixed. 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 or viscosity, shear strength (such as penetration measurement using cones). 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 rate pressure control device 32 and a centralized management 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 27 is first provided and filled with a pressurized container, 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. 7, 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. 9, for example, liquid injection system data (a total of 40 data of flow rate, pressure, integrated flow rate, and maximum pressure) at the time of injection having 10 liquid supply systems is displayed on a single screen on the injection monitoring panel X2. Shows the screen. The screen of FIG. 9 will be described in detail as follows.

Upper two screens:
Group 1: No. 1 to No. 5 integrated flow rate and maximum pressure digital display Group 2: No. 6 to No. 10 integrated flow rate and maximum pressure digital display integrated flow rate are infusions 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: No. 1 to No. 5 flow rate and pressure trend display Group 4: No. 6 to No. 10 flow rate and pressure Trend display 2 The left side of each 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. The pressure, flow rate, and chart can be displayed together with the stage number.

  Further, from these data, for example, the block No. of FIG. 1. Injection hole No. If 3 is displayed, the injection pressure P, the flow rate Q, and the integrated flow rate with respect to time t can be displayed for each stage as shown in FIG. Also, 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 to. 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 ・ Coal ash discharged from fly ash thermal power plant: FA,
Density 1.9 to 2.3 g / cm ³ , particle size distribution 0.1 mm or less is 90% or more (2) Incineration ash density 2.5 to 2.7 g / cm ³ discharged from incineration ash waste incinerator
(3) Cement ordinary Portland cement: PC, hardening expression material (4) sulfate aluminum sulfate, Al ₂ O ₃ = 17.2%, gelation accelerator (5) water glass
JIS No. 3 water glass, SiO ₂ = 29.0%, Na ₂ O = 9.0%, molar ratio 3.3
(6) calcium hydroxide for slaked lime industry (7) slag slag 8000 brane value (8) gypsum hemihydrate gypsum

Formulation Examples 1-3
Mix fly ash, cement and water. The blending amount of fly ash and cement was similarly changed only in the blending amount of water. Table 1 below shows the adjustment conditions and physical property values of the ground injection materials of Formulation Examples 1 to 3 thus obtained.

  In Table 1, gelation time refers to the time to exhibit a plastic gel. The plastic holding time refers to the time during which a gel-like state is maintained if it is stationary, but is in a state of flowing when a force is applied. In order to make a non-flowable plastic grout immediately after blending, as shown in Formulation Example 3, it is considered that the water powder ratio needs to be 25% or less. However, the finished grout properties vary depending on the mixing conditions and the materials used. Therefore, it is important to measure not only the blending ratio but also the above breathing, flow and strength.

Formulation Examples 4-6
Mix fly ash, cement and water. The amount of water was changed in the same manner as that of fly ash and cement. Table 2 below shows the adjustment conditions and physical property values of the ground injection materials of Formulation Examples 4 to 6 thus obtained.

  From Table 2, when the PC addition amount is increased, the breathing rate is increased, the plastic holding time is shortened, and the initial viscosity is also increased, so that workability is also lowered. Therefore, the PC addition amount is less than 50%, preferably 1 to 20%, more preferably 1 to 15%, and most preferably 1 to 10%. In the present invention, blast furnace cement, alumina cement, early-strength cement, slag cement, or any other cement can be used instead of Portland cement.

Formulation Examples 7 and 8
A sulfate band was added to Formulation Examples 1 and 2 in Table 1 to promote gelation. Here, to promote gelation means to shorten the time until the plasticity is exhibited after blending or to reduce the flow. Table 3 below shows the adjustment conditions and physical property values of the ground injection materials of Formulation Examples 7 and 8 thus obtained.

  From Table 3, it is considered that by adding a sulfuric acid band, the gel time is shortened, but the plastic holding time is not so much reduced, and the breathing rate is also reduced, so that the workability as a plastic grout can be improved. However, since the sulfuric acid band has the property of reducing the strength expression, the addition amount is within 2.0%, preferably within 1.0% with respect to the powder.

[Factors and conditions as plastic grout]
(1) Hardening material ratio Powder contained in grout, that is, fly ash, and cement content relative to cement content: cement weight / (fly ash weight + cement weight) × 100 (%)
Cement is a material that develops hardening, and can also be called fly ash plasticizer. When fly ash is mixed with cement, it causes a pozzolanic reaction to obtain consolidated strength. However, as the amount of PC added is increased, the properties as a plastic grout deteriorate. In other words, since the precipitated and increased breathing and the precipitated are difficult to flow and hardly form a plastic gel, the PC addition amount is less than 50%, but the preferred range is when no sulfuric acid band (gelling accelerator) is added It is 1 to 20%, preferably 1 to 15%, more preferably 1 to 10%. Moreover, when adding a sulfuric acid band, it is 2 to 40%, Preferably it is 2 to 20%.

(2) Water-to-powder ratio Water content with respect to powder in grout: water weight / (fly ash (incineration ash) weight + cement 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 20 to 150%, preferably 20 to 60%. However, the properties of the grout differ depending on the mixing conditions, environment, and materials, so the measurement of breathing rate, flow value, and strength, which will be described later, is important.

(3) Amount of sulfate band added Amount of sulfate band added to the powder in the grout: sulfate band weight / (fly ash weight + cement weight) × 100 (%)
The sulfuric acid band is a gelation accelerator, and when added to the fluid state of fly ash 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%.

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

(5) 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. The time from exceeding 0.1 MN / m ² was regarded as consolidation, and the time from gelation to consolidation was defined as the plastic holding time.

(6) After blending the breathing rate, mix the grout thoroughly, then place the grout in a 200 ml 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 5% or more after the lapse of 1 hour, the breathing rate further increases as time passes. Therefore, the blending rate within 5% of the breathing rate after 1 hour is preferable. FIG. 12 shows the relationship between the water powder ratio and the breathing rate according to the presence or absence of the sulfate band in Tables 1 and 3.

(7) Flow value Based on the flow test (JIS R 5201), the grouting was subjected to 15 falling motions in 15 seconds and the spread was measured. About 18-19 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. Even when the water powder ratio is 20 to 150%, when it is injected into the ground, the water powder ratio decreases due to dehydration, and the flow becomes 20 cm or less and gelation occurs.

  Further, even if the water powder ratio is large in this range, if the water powder ratio is 20% or less in the ground due to dehydration, the plastic gel is solidified through a non-plastic gel.

  In the present invention, the mixture of fly ash and a powder that is a hardening developing material itself becomes a plastic gel over time or by dehydration in the ground, and in the present invention, the plastic gel product itself is injected. In this case, the plastic grout is 13 to 28 cm, preferably 15 to 24 cm, more preferably 18 to 23 cm. This is in consideration of dewatering by pressing the grout into the ground, pumping ability and workability. Moreover, at the time of injection | pouring, even if it mix | blends the flow of 28 cm or more, it will become a plastic gel by dehydrating in the ground.

The flow that the injected solution is most likely to solidify is about 18 to 19 cm. However, in the present invention, dehydration from the grout occurs by press-fitting into the ground, so that even in the state of good fluidity as described above, Thus, it becomes plastic and can form a massive consolidated body. In addition, as described above, the flow is within 28 cm or the water powder ratio is 20 to 150 by adding a retarder near the gelation by slowing the dehydration action by the initial low pressure injection and interval injection. % Infusion solution can be applied. The optimal flow can be set according to the ground conditions, equipment used, equipment, and design conditions. X in the table indicates that the grout could not be measured due to fluidity.

(8) Initial viscosity
The viscosity of the blended liquid immediately after blending was measured using the B-type viscosity form. Immediately after mixing, measurement was possible due to fluidity, but when gelled, it becomes 100,000 cps or more and measurement is impossible. FIG. 13 shows the relationship between the water powder ratio and the uniaxial compressive strength according to the presence or absence of the sulfuric acid band in Tables 1 and 3.

(9) After blending the uniaxial compressive strength, the fully mixed grout was packed in a mold having a diameter of 5 cm and a height of 10 cm, and was cured for one day in a stationary state, and the uniaxial compressive strength was measured. FIG. 14 shows the relationship between the water powder ratio and the uniaxial compressive strength according to the presence or absence of the sulfate band in Tables 1 and 3.

  According to FIG. 14, the strength is reduced by the addition of the sulfuric acid band. In addition, when the water powder ratio is large, the time until consolidation is prolonged, so that the strength development is slower than that when the water powder ratio is small.

Formulation Examples 9-11
A water glass is diluted with water, and a suspension in which fly ash, cement, slaked lime, and water are mixed is mixed therewith. Table 4 below shows the preparation conditions and physical property values of the ground injection materials of Formulation Examples 9 to 11 thus obtained.

(1) Addition amount of slaked lime Addition amount of slaked lime to powder in grout Addition amount of slaked lime / (fly ash weight + cement weight) x 100 (%)
Slaked lime is a gelling accelerator, and when mixed with fly ash like cement, it causes a polazone reaction. However, consolidation strength is not as good as cement. Here, it was used as a gelation accelerator for making it plastic and for having the retention time. The range is 3 to 15% depending on the amount of cement added.

(2) Silica concentration SiO ₂ amount in grout SiO ₂ % of water glass × (water glass weight / grouting weight) (%)
According to the experiment by the present applicant, the silica concentration is set to 0.2 to 7.0% in order to plasticize and solidify the grout, although it depends on the blending ratio of other materials. However, when a low molar ratio water glass having a molar ratio of No. 3 water glass or less is used, 3.0 to 7.0% is preferable. Of course, a high molar ratio water glass or powdered water glass can also be used.

(3) Characteristics and comparison As a characteristic of this formulation, gel time can be easily prepared, and the plasticity retention time is slightly short, but the early strength development is remarkable. Therefore, it is suitable when importance is placed on the expression of early strength. Further, by kneading the grout well after gelation, the expression of early strength is reduced, but the plastic holding time can be lengthened. Therefore, it is suitable for ground improvement in which the injection body is expanded by injecting the mixture well-mixed after gelation for the purpose of requiring long-time injection or repeated injection at the injection point once injected by interval injection.

Formulation Example 12
In the blending example 2, cement was used as the hardening developing material, but slaked lime is used as the hardening developing material with the same blending amount. The adjustment conditions and physical property values of the ground injection material of Formulation Example 12 obtained in this way are shown in Table 5 below.

Formulation Example 13
In the blending example 2, cement is used as the hardening developing material, but slag is used as the hardening developing material with the same blending amount. The adjustment conditions and physical property values of the ground injection material of Formulation Example 13 obtained in this manner are shown in Table 6 below.

Formulation Example 14
Gypsum is used as the curing agent. Table 7 below shows the adjustment conditions and physical property values of the ground injection material of Formulation Example 14 obtained as described above.

(1) Curing material addition amount Curing material content relative to powder content in grout: Curing material weight / (fly ash weight + curing material weight) × 100 (%)
It is the same as the PC addition amount shown in Formulation Examples 1-11, and in Formulation Examples 12-14, since slaked lime, slag, and gypsum were used as the curing material, it means slaked lime addition amount, slag addition amount, and gypsum addition amount. . However, since the addition amount of the slaked lime of the combination examples 9-11 is used as a gelling accelerator, the purpose of use of the slaked lime of the combination example 9 is different. Therefore, it was described as the amount of hardener added.

(2) Characteristics and Comparison of Formulation Example 12 When slaked lime is used as a hardening-producing material, a pozzolanic reaction occurs when added to fly ash as with cement, but this reaction is very slow, so it becomes plastic but hard. It takes time to set, and it takes several weeks to obtain sufficient consolidation strength. However, since it is more likely to become plastic than using the same amount of cement, an excellent effect can be expected when used in combination with cement.

(3) Characteristics and Comparison of Formulation Example 13 When slag is used as a hardening developing material, it gels slightly faster than cement and the plastic holding time becomes longer, but the result is similar to cement. However, since the strength development is slower than that of cement, when promoting gelation using a plasticizer such as a sulfuric acid band, the sulfuric acid band has the property of reducing the long-term strength, so be careful of the amount added. Necessary.

(4) Characteristics and Comparison of Formulation Example 14 When gypsum is used as a curing material, gypsum tends to be plastic because it reacts quickly,
Since the development of strength is fast, the plastic holding time is extremely short. Therefore, the application range is limited.

Formulation Examples 15 and 16
As a two-component formulation, a plasticizer was further added to the above-mentioned grout that was mixed with fly ash, cement, water, and a plasticizer and became plastic over time, thereby increasing the gel time. Using the above formulation example 7 containing fly ash, cement, water, and a plasticizer, a sulfuric acid band aqueous solution and an aqueous solution obtained by diluting water glass with water are added to the fluidity state before gelation. did. The blending ratio was 1 for the plasticizer aqueous solution with respect to 20 for the grout of Formulation Example 7. The adjustment conditions and physical property values of the ground injection materials of Formulation Examples 15 and 16 thus obtained are shown in Tables 8 and 9 below.

(1) Characteristics and Comparison of Formulation Examples 15 and 16 When an aqueous sulfuric acid band solution was added to a fluid grout, the gel time was shortened due to an increase in the amount of sulfuric acid band added to the grout, but the strength was affected. Further, when an aqueous solution obtained by diluting water glass with water is added, the gel time becomes extremely short and the plastic holding time becomes short, but the strength development is remarkable. Therefore, it is suitable when importance is placed on the expression of early strength. As a two-component compounding, it is considered that the compounding using water glass as a plasticizer provides an excellent effect.

Formulation Example 17
Incineration ash was mixed with the fly ash of Formulation Example 3 in Table 1. The mixing ratio of fly ash and incineration ash is 1: 1. Table 10 below shows the adjustment conditions and physical property values of the ground injection material of Formulation Example 17 obtained as described above.

Formulation Example 18
Cement was added to the fly ash as a hardening developing material, and bentonite was further mixed. Table 11 below shows the preparation conditions and physical property values of the ground injection material of Formulation Example 18.

(1) Water powder ratio Water content to powder in grout: water weight / (fly ash weight + cement weight + incinerated ash amount or bentonite weight) × 100 (%)
Here, incinerated ash and bentonite were used as examples as powders other than the cured material and fly ash. In addition, on-site generated soil or silica sand can be used. These fillers can also be used as aggregates and aggregates, and the fluidity and strength can be adjusted by the particle size and particle size.

(2) Characteristics and Comparison of Formulation Example 17 When comparing Formulation Example 17 in Table 10 and Formulation Example 3 in Table 1, the blending example 17 mixed with incinerated ash has a reduced breathing rate and a smaller flow value. It was. When incinerated ash is mixed, it is considered that the fluidity tends to be lost more easily than the case of fly ash alone, and the strength development tends to decrease. The ratio of cured material is less than 50%, preferably 1 to 20%, and water powder is 20 to 150%.

(3) Characteristics and Comparison of Formulation Example 18 In the case of adding fly ash (cement + bentonite), although the reaction is slightly slower than when only the same amount of cement is used, plastic solidification (plastic state retention time) ) Was not much different. However, when the addition amount of cement is reduced by adding bentonite, the consolidation strength is lowered. Therefore, the 4 kinetics can be adjusted by setting the PC addition amount to 3% or more and using bentonite as a thickener. The ratio of cured material is less than 50%, preferably 1 to 20%, and the water powder ratio is 20 to 150%.

Formulation Examples 19 and 20
As an air generating agent, a prefoaming foaming agent and a post foaming aluminum powder were mixed with fly ash and cement mortar. As a blend using a foaming agent, fly ash was added to a general blend of air milk. The same applies to the aluminum powder for comparison. Standard addition amounts were added to both the foaming agent and the aluminum powder. The preparation conditions and physical property values of the ground injection materials of Formulation Examples 19 and 20 are shown in Tables 12 and 13 below.

(1) Foaming agent addition amount Foaming agent content to cement contained in grout: foaming agent weight / (cement weight) × 100 (%)
The amount of foaming agent added is defined by the weight ratio of cement. The standard amount of foaming agent used was 0.5 to 1.5% (weight ratio of cement). Therefore, we will follow that range.

(2) Aluminum powder addition amount Aluminum powder content with respect to the powder contained in the grout: aluminum powder weight / (fly ash weight + cement weight) × 100 (%)
Aluminum powder reacts with alkali such as cement to generate hydrogen gas (foaming). However, since fly ash also contains alkali, the amount of aluminum powder added is relative to the total amount of cement and fly ash. If this amount added is determined by the cement to cement ratio, the amount of bubbles generated is very small during blending, and the effect as an air generating agent is not exhibited. Therefore, since the standard addition amount of the used aluminum powder was 0.01% (to cement ratio), the aluminum powder addition amount was set to 0.01% (to fly ash + cement ratio) here.

(3) Characteristics and Comparison of Formulation Examples 19 and 20 Plastic grouts using air have different plastic grout properties as described above, and lose the grout fluidity by mixing a large amount of bubbles in the grout. Therefore, it becomes a grout with a relatively small specific gravity. The foaming agent is prefoamed aluminum, reacts with alkali to generate hydrogen gas and expand the grout. Since the reaction takes about 10 to 100 minutes from the blending, the gel time is also in the meantime. If the amount of cement added is small, the consolidation strength decreases, so the amount of PC added is preferably 7% or more.

  The formation of a massive solid body, which is a feature of the present invention, was examined using a conventional water glass-based suspension-type instantaneous setting (hereinafter referred to as an instantaneous setting), a water glass-cement LW, and a plastic injection material. The results are shown in Table 14 below. Comparative Example 1 in Table 14 is an instantaneous setting, and Comparative Example 2 is LW. The formulations of Comparative Example 1 and Comparative Example 2 are shown in Table 15 and Table 16, respectively. In Comparative Example 2, Comparative Example 3, and Practical Example, two kinds of powdery materials and water in the present invention are mixed at a water powder ratio and a hardening developing material ratio shown in Table 14. In the following composition, fly ash was used as the main material of the powdery material, and cement was used as the hardening material. The target ground is sandy ground with an N value of 7, a relative density of 40%, and a fine grain content of less than 20%.

  Comparative Examples 1 to 3 were injected into the ground as veins. In Comparative Example 4 and practical example, the water powder ratio is small, the slump is 26 or less, the flow value is 13 to 28 cm, and it is confirmed that a solid consolidated body is formed on the ground by press-fitting into the ground. It was. In Comparative Example 4, the ratio of the cured material was large, so that the grout was fastened, resulting in a pulmonary solid having a thickness of 15 cm or less. Therefore, in order to create a large solid body of 20 cm or more in the ground, the water powder ratio is 20 to 150%, the cured material ratio is 1 to 40%, preferably 1 to 20%, and the flow is 13 to 28 cm. It can be seen that the ground injection material of the present invention is suitable.

  In addition, when a plastic injection material having the composition shown in Tables 17 and 18 below used in conventional backfill injection is pressed into the ground, it splits into the ground and unevenly deviates out of the ground, resulting in massive solidification. Proved difficult.

  As a result of the research by the test construction shown in FIG. 1 in the present invention, it was found that the ground reinforcement effect can be obtained by the injection design as follows.

In FIG. 1, the injection interval is 0.5 to 3.0 m. The improvement rate is 5 to 40%. Here corresponds to the cross-sectional area of the caking mass in terms of sharing improvement area 1 m ² per one injection hole and the improvement ratio, the improvement ratio 5-40% means 0.05~0.4m ^2. In addition, this improvement rate is calculated from the N value of the improvement target ground and the improvement target N value, and the reduction amount of the gap in the area per hole is calculated, and the reduction amount corresponds to the area to be replaced by the gelled product. Is calculated from Table 17 shows design examples effective as ground reinforcement in the present invention. This is based on the experimental example performed on the sand ground in Example 2, the injection arrangement is a square arrangement shown in FIG. 1 (b), the injection interval is 1 m, 2 m, and the improvement rate is 5%, 10%, 15% and 20%.

  It is necessary to set the injection rate (l / min) and the injection pressure per minute so that the injection amount calculated in this way falls within a predetermined depth. For this purpose, it has been found that it is desirable to perform injection while controlling injection at a discharge rate of 5 to 50 l / min per minute and an injection pressure of 0.5 to 10 MP.

  At this time, it was found that if the ground uplift is within 20 cm, preferably within 10 cm, the gel in the ground will be dehydrated and the ground uplift will be about 5-10 cm after a few days.

Further, it was found that the ground was slightly prone to rise when the implantation depth was shallower than GL 3.0 m, and raised to 10 cm or more when the depth was less than GL 1.5 m. Accordingly, it has been found that it is effective to take measures to prevent the ground from being raised at a depth of 3.0 m or less, or 1.5 m or less. Further, it has been found that the ground improvement effect is possible only when the ground is compressed by being pressed into each other by press-fitting from a plurality of holes in the range of the injection hole interval.

  Coal ash (FA) discharged from thermal power plant as fly ash of main agent, cement (C) as solidification material, sulfuric acid band (B) as additive, 400 g of FA agent, 35 g of C agent, B agent FIG. 15 shows the change in the flow value (cm) of each injection material when the water powder ratio is changed from 25 to 30 (%) by changing the amount of water to 2.16 g. It was. FIG. 15 is a graph showing the relationship between the water powder ratio (%) one minute after blending and the flow value. The blending amounts are shown in Table 20.

  In Table 20, each injection material of each formulation loses its fluidity in the process of changing from a liquid state to a consolidated state, but has a characteristic of easily flowing when pressurized. In addition, the injection material which has arbitrary fluidity | liquidity and caking property can be obtained by using the sulfuric acid band (B) as an additive.

  As can be seen from Table 20 and FIG. 15, when the mixing ratio of coal ash (FA) and sulfuric acid band (B) is made constant, the amount of water (W) is added little by little to increase the water powder ratio (%). The water powder ratio increases accordingly, and the flow value (cm) with respect to the water powder ratio (%) changes almost linearly as shown in FIG. Thereby, the flow value can be managed in the field by adjusting only the amount of water with the same composition.

  In addition, as can be seen by comparing Table 1 and Table 20, the flow value can be increased by increasing the addition amount of the sulfuric acid band (B) from zero, and by the passage of time from mixing to injection into the ground. The most appropriate flow value can be set by changing. Moreover, if it spin-dry | dehydrates in the ground, the water-powder ratio will become large, and even if it is large flow value before injection | pouring, it can flow in the ground and the gelled material which expands with a gelled lump can be formed.

  In general, the suspension of fly ash itself is non-hardening and excellent in fluidity. However, when a small amount of cement is added to this, cement particles intervene between the fly ash, and the calcium ions of the cement are lost. Electrochemically weakly connects fly ash particles to form a structure that is difficult to disperse and has fluidity. This flow characteristic varies depending on the amount of cement to fly ash.

  Furthermore, the cement undergoes a hydration reaction with time, and the fluidity decreases as it progresses. This flow characteristic varies depending on the water powder ratio. It also varies depending on the amount of aluminum or silica. By adjusting the blending and effectively utilizing the change in fluidity from blending to the elapsed time, it can form a solidified gel that expands and eventually solidifies without departing from the ground. Form objects, strengthen the ground by increasing the density of the ground.

It is a ground reinforcement model diagram by plastic grout press-fitting, (A) is a cross-sectional view of solidified columns by plastic grout for the area to be improved, (B) and (C) are a plan view and an injection arrangement diagram of plastic injection material. is there. (B) is a square layout, and (C) is a triangular layout. (A) is sectional drawing of the aspect of injection | pouring by the rod injection pipe of the plastic gel grout through the drilling hole formed adjacent to the ground of a predetermined area, (b) is adjacent to the ground of a predetermined area. It is sectional drawing of the aspect by the interval system of the injection | pouring of the plastic grout gel grout through the drilling hole formed, and (c) is a sectional view of the injection construction by the packer system, and the lateral expansion of the packer bag over time It is a side view. It is a schematic diagram of the displacement measurement aspect in the middle of construction of the ground. (A) is a basic schematic diagram of the ground treatment to be improved directly under the structure, and (b) is a longitudinal sectional view of a ground injection example below the structure. (A) is a schematic view of press fitting of a plastic grout by pulling out a casing, (b) is a cross-sectional view of ground reinforcement of a pile foundation by plastic grout, and (c) is an anchor formation by press fitting of a plastic grout in a retaining wall FIG. 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 difference of the breathing rate by the presence or absence of a sulfuric acid band. It is a graph showing the difference of the initial viscosity by the presence or absence of a sulfuric acid band. It is a graph showing the difference in strength expression by the presence or absence of a sulfate band. It is a graph showing the relationship between water powder ratio (%) and flow value (cm).

Explanation of symbols

3 Ground 4 Drilling 5 Valve 6 Controller 7 Computer 8 Casing 9 Injection Pipe

Claims (1)

The following ground injection material through a plurality of injection holes provided in the ground: (1) Fly ash (F material)
(2) One or more kinds of calcium-based powdery hardening material (C material) selected from the group of cement, lime, gypsum and slag
(3) Water (W material)
3 as an active ingredient , the cured material ratio C / (F + C) × 100 (%) is 1 to 20% by weight , and the water powder ratio W / (F + C) × 100 (%) is 20 to 150. In the ground strengthening method for injecting a ground injection material having a weight (%), a slump (cm) at the time of injection of 4 to 26 cm, and a flow (cm) of 13 to 28 cm , the ground injection material is plastic. a ground injection material, per injection, using a injection tube having a discharge opening at the tip, the simultaneous injection method of a plurality of injection points injection, continuous note input method, interval injection method, by the intermittent injection method or a combination method to and the initial injection pressure to the lower injection was started, the aim of dehydration of the preceding injection material increases the injection pressure while reducing gel formation of the ground grout, thereby inter soil particles by gel land Release grout penetration And ground The split soil particles child while preventing deviations due to cracks in spread around while increasing the density of ground strengthening the ground, and to move the injection tube up or down the injection hole spacing as 0.5m~3m injected while migrating stages and pressed the plastic ground grout, forces the soil particles to the surroundings by pressing the gelation of the injected material, a plurality of bulk consisting gelled plasticity ground grout into the ground Te A ground strengthening method characterized by forming a consolidated body and strengthening the ground by increasing the density of the ground between a plurality of injection holes. However, in the above, W, F, and C each show weight.

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