JP2824941B2 - Double grouting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double grouting method for stabilizing the ground using a soil stabilizer.

[0002]

2. Description of the Related Art For the improvement of soft ground, foundation work for underground structures, ground excavation work, etc., in order to stop water from spring water, underground water, leakage, etc. in the ground, or to prevent ground collapse. The method of injecting a ground stabilizing chemical solution containing a soil stabilizer (hereinafter simply referred to as a chemical solution) into the ground using an injection pipe is roughly classified into a low-pressure injection method and a high-pressure injection injection method. be able to. 1) The low-pressure injection method is a method in which a chemical solution is injected into the ground at a pressure of less than 50 kg / cm ² , and penetrates into soil or penetrates into cracks to be hardened to stabilize the ground. 2) The high-pressure injection injection method uses a pressure of 50 kg / cm ² or more to pressurize the chemical itself or use a gas for pressurizing the chemical,
This is a method of injecting a chemical solution from an injection nozzle into the ground, cutting the soil in the ground with an injection fluid containing the chemical solution, and simultaneously mixing and mixing the chemical solution and the soil particles to form a hardened body, thereby stabilizing the ground. Conventionally, each of these construction methods is independently performed.

[0003] The low-pressure injection method has the following problems. Injecting a chemical solution into the ground under low pressure and allowing it to penetrate into the soil and harden to form a solidified mass with a large amount of consolidation, usually a chemical solution with a hardening time (gel time) longer than 30 seconds Is used. However, when an injection pipe is generally inserted and installed in the ground, a drilling liquid such as water is sent through the injection pipe and inserted while cutting the ground, so that an insertion hole wall formed in the ground is installed. There are many gaps in the ground around the filled injection pipe. Therefore, when the hardening time of the chemical liquid injected into the ground is long, it is inserted through the gap between the injection pipe and the ground, which has a lower resistance than that which penetrates into the unexcavated soil where the earth pressure resistance is higher. It is easy to flow toward the hole and to the surface.
Further, in general, the chemical liquid injected into the ground tends to permeate and flow out to the ground surface rather than permeate deep into the ground due to the influence of the ground pressure resistance particularly when the hardening time is long. In addition, the injected chemical permeates only into the easily permeated part of the ground and flows out of groundwater, or a hardened body is formed outside the area intended for improvement, and the desired sediment-solidified body is formed at the target location There is a problem that the loss of the chemical solution is large due to the lack of the formation, and a volume of the sediment-solidified body corresponding to the amount of the injected chemical solution cannot be obtained. Furthermore, the chemical liquid injected into the flowing water / spring area in the ground is diluted with water, and the strength of the formed solidified solid is small, and further, the injected chemical liquid does not flow out and solidify with the flowing water. In some cases, the stabilization of the ground becomes uncertain.

[0004] On the other hand, when a chemical solution having a short curing time is used, the chemical solution is cured in a region closer to the injection pipe as the curing time is shorter, and a sediment-solidified body is generally formed at a target portion.
Since the speed of the curing reaction is high and the viscosity of the chemical solution increases in a short time, the permeability into the soil is reduced, and the volume of the compacted soil formed is small and the amount of compacted soil is small. When the injection pressure of the chemical is increased to widen the penetration range of the chemical, the amount of solidified soil can be slightly increased, but a pulsating homogel body is easily formed, and the solidified per unit of the injected chemical is Low soil volume. In addition, since the adhesive strength between the homogel and the sand gel is low, the strength of the formed soil-sand compact is reduced as a whole. In addition, if the injection pressure of the chemical solution is increased, the ground may be raised.

In order to solve these problems, a method called a composite grout injection method in which a chemical solution having a short curing time and a chemical solution having a long curing time are combined and injected has been proposed. There is a problem. In the compound grout injection method, first, a chemical solution with a short curing time is injected and hardened around the injection tube to form a strong grout packer in order to prevent the chemical solution from flowing out of the injection tube toward the insertion hole. After that, a chemical solution having a long curing time is injected.
However, since the hardened material has already been formed around the injection pipe, the penetration of the chemical solution into the soil is hindered. Can not be obtained. In a state where the chemical liquid is hard to penetrate into the soil, generally, the injection (discharge) amount of the chemical liquid is reduced, the injection pressure is increased, the time required for injecting a predetermined amount of the chemical liquid is increased, and the work efficiency is reduced.

Next, as a high-pressure injection injection method, a method of injecting a chemical solution itself into the ground under high pressure (for example,
50-863, Japanese Patent Publication No. 50-14803, and Japanese Patent Publication No. 51-8493). In addition, as a method for improving these, a method of using a gas for pressurizing a chemical solution together (for example, Japanese Patent Publication No. 58-27364,
Publications such as Japanese Patent Publication No. 56-44206). However, even in these methods, the amount of solidified soil by the chemical solution is small. The diameter of the formed soil compact is small, and the effective compaction efficiency of the soil per injected chemical solution is small. Also, in general,
In the high-pressure injection injection method, a large amount of the mixture of the chemical solution and the earth particles is discharged, and the treatment of the mixture requires a large cost. In addition, since the amount of the chemical solution injected per unit time is large, the loss of the chemical solution when the chemical solution flows out is large, and there is a problem that the problem of the treatment of the chemical solution flowing out is caused. Even in the high-pressure injection injection method, when a chemical solution having a hardening time of about 30 seconds to about 10 minutes or less is used, a hardened body is formed around the injection pipe. If this is strong, the formed hardened body cannot be cut even if the chemical solution is sprayed under high pressure, and the chemical solution and the soil particles are not sufficiently mixed. In some cases, the amount of solidified soil of the body is small, and a portion that does not solidify remains, so that a continuous earth and sand consolidated body is not formed. From such unjoined parts, ground subsidence or collapse may occur due to groundwater downstream.

As described above, as a conventional chemical liquid injection method,
Both the low-pressure injection method and the high-pressure injection injection method have their own problems, and it may be difficult to stabilize the ground in a complicated state when they are constructed independently. The common cause of these methods is that
This means that it is difficult to fill a sufficient amount of the ground stabilizing solution into the area to be stabilized in the ground when each is constructed independently.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the problems of the prior art and to fill a sufficient amount of a ground stabilizing chemical in a target area in the ground to be stabilized. It is an object of the present invention to provide a method for stabilizing the ground more safely and more reliably, which can obtain an earth-and-sand compact having a large amount of consolidated soil and high strength.

[0009]

Means for Solving the Problems The present inventors have conducted intensive research and, when a chemical solution is to be injected into the ground to be stabilized, properly combine a low-pressure injection method and a high-pressure injection method. By doing so, it has been found that the problems of the prior art can be solved and the object of the present invention can be achieved.

The present invention relates to a method for stabilizing the ground by injecting and hardening a ground stabilizing chemical into the ground to form a solidified earth and sand. During the injection of the ground stabilizing chemical, the injection of the chemical is interrupted, and after the high-pressure injection of the cutting fluid instead of the chemical into the area, the ground stabilizing chemical is further injected. Grit injection method ".

The chemical used in the method of the present invention includes:
There is no particular limitation as long as it is injected into the ground and hardened. The main agent is usually a cement type; an alkali silicate type, a silicate ester type, a so-called acidic silicate type obtained by acidifying an alkali silicate with an acid, or a dispersion of silicic acid obtained by de-alkali or de-esterification from an alkali silicate or a silicate ester. (Colloidal silica, silica sol, colloidal solution of silicic acid, aqueous solution of destabilized silicic acid, aqueous solution of activated silicic acid, etc.); Polymer-based soil stabilizers such as polyurethane-based, urethane resin-based, polyethylene glycol dimethacrylate-based, and polyethylene glycol diacrylate-based. Two or more of these systems having compatibility can be used in combination. Then, a curing agent or a polymerization catalyst suitable for each of the above-described main components may be selected, and the ratio may be appropriately adjusted so as to obtain a desired curing time.

In the present invention, the injection of the chemical solution is suspended while the chemical solution for ground stabilization is being injected into the region of the ground to be stabilized, and the cutting fluid is replaced in the region with the chemical liquid. Is subjected to high-pressure injection injection processing. With this process,
A homogel body of the chemical formed in the space between the injection pipe and the wall of the insertion pipe insertion hole, or a solid-solid (sand-gel body) formed by hardening of the chemical that has penetrated into the soil near the insertion hole wall In addition to actively cutting the hardened body formed at the periphery of the injection pipe and collapsing, the earth and sand in the ground are cut, mixed and stirred. Accordingly, the state of the target area in the ground to be stabilized can be set to a state in which the injected chemical liquid easily permeates into the soil or is easily mixed with the earth and sand in the ground. By incorporating a high-pressure injection of cutting fluid into the ground stabilization liquid injection process, a sufficient amount of ground stabilization liquid is filled under low pressure in the target area of the ground to be stabilized. , Large amount of consolidated soil, and
It is possible to form a compacted earth and sand having high strength and to reliably stabilize the ground.

In the present invention, the cutting fluid used for cutting and breaking the hardened material or earth and sand formed around the injection pipe is water or other high-pressure drilling fluid or cutting fluid generally used in a boring process. The ground stabilization chemical liquid that has a longer curing time than the chemical liquid that was injected into the ground before performing the injection injection processing, or any one of the ground stabilization chemical liquids that combines two or more liquids Can be used. Of these, if a ground stabilizing chemical liquid is used as a cutting liquid that has a longer curing time than the chemical liquid injected into the ground before high-pressure injection processing of the cutting liquid, the cutting liquid itself will also harden in the ground. It is preferable because a solidified earth and sand can be formed.

As an embodiment of using the cutting fluid in the method of the present invention, when the hardening of the chemical injected into the ground progresses and the pressure required to inject the chemical increases and the injection speed of the chemical decreases, Then, the injection of the chemical liquid is interrupted, and a high-pressure injection of a cutting liquid instead of the chemical liquid is performed in order to cut and break the formed hardened body. When a chemical solution having a short curing time, which is a combination of two or more liquids, is used, only one of the liquids can be used as a cutting liquid for high-pressure injection. Depending on the condition of the soil in the target area in the ground to be stabilized, resistance may be high when the chemical solution is injected, and the pressure required to inject the chemical solution may increase. By applying the method of the present invention, high-pressure injection of cutting fluid can be performed instead of chemical liquid.

The injection amount of the cutting fluid and the number of injection injection processes used in the method of the present invention are not particularly limited.
The injection amount of the cutting fluid in the same injection hole is preferably in the range of usually 0.5 to 100 l per 1 m section. When the injection amount of the cutting fluid is less than 0.5 l, the degree of cutting the formed hardened body and soil is small, and the pressure required for the injection of the chemical solution during the injection of the chemical solution after the injection processing of the cutting fluid is short. Therefore, the injection and injection processing of the cutting fluid is frequently repeated, and frequent switching of the injection fluid is required, and the operation becomes complicated. Further, even if the injection amount exceeds 100 l, the effect of cutting the hardened material and the soil is not improved so much, which is not advisable.

The injection pressure of the cutting fluid is usually 50 to 1000 kg / cm
The range is ² , and a higher value is more preferable because the cutting effect is improved.
If the injection pressure is less than 50 kg / cm ² , the time required for cutting the hardened body and the amount of cutting fluid increase, and if it exceeds 1000 kg / cm ² , the amount of cutting fluid loss increases.

The ground stabilizing chemical liquid to be injected into the ground after the injection of the cutting liquid is performed is as described above. The hardening time of the chemical liquid is 30 seconds or less,
Longer than 1 second, and curing time of 1
Any of the loose binding types that are on the order of days can be used. In order to form a compacted earth and sand with a large amount of consolidated soil, it is preferable that the hardening time be about ten minutes to one hour.

A chemical solution having a short curing time may lose its permeability at an early stage and a solidified material with a large amount of consolidated soil may not be obtained. It is preferable to adjust the curing time so long that the curing time is not lost, and it can be adjusted so that the curing time is shortened as the injection time elapses. As the chemical used in the low-pressure injection step in the method of the present invention, the curing time is usually 30
A slow-setting type which cures in at least one second, preferably at least one minute, more preferably at least ten minutes, most preferably at least 60 minutes, or about one to two days, which does not cure during the pouring operation, is suitable.
Although a chemical solution having a curing time of about one week can be used, an excessively long one exceeding one week is not preferable because the curing is insufficient and the gel strength is low.

Injection of the chemical solution in the method of the present invention may be performed by either low-pressure injection or high-pressure injection injection, and may be performed according to the low-pressure injection or high-pressure injection injection method which is performed by a normal chemical injection method. .

The pressure at which the chemical liquid low-pressure injection is not particularly limited if there is a difference depending on the state of the soil, the range of usually 0~50kg / cm ² in gage pressure, preferably 20 kg / cm ² or less, more preferably Is 10 kg / cm ² or less.

The pressure at the time of injecting and injecting the chemical at a high pressure is not particularly limited because it varies depending on the state of the ground, but is usually in the range of 50 to 1000 kg / cm ^2. .

An injection pipe for injecting a chemical solution into the ground is
The one used in the ordinary chemical injection method can be used. In the case of a chemical solution with a long curing time, use a single tube type injection tube, and use a one-pack type chemical solution as it is, and mix a chemical solution composed of two or more types of liquids and send them to the injection tube. Insert and inject. For chemicals with a short curing time,
At least two independent, such as multi-tube and multi-tube,
An injection tube having a channel for a chemical solution and having a structure capable of mixing each of the fed liquids immediately before injection into the ground is used.

An injection pipe for injecting a high-pressure injection of a liquid for injection or a cutting liquid is of a type which is used in a normal high-pressure injection and injection method, in which the liquid itself is injected under high pressure, and a gas for pressurizing the liquid. Any of the methods using the same method can be used.

Further, as shown in FIG. 1-A, at least two independent flow paths 2 are provided, and the front end side of each flow path 2 is an injection pipe.
1 communicates with the chemical mixture chamber 3 provided at the tip of
A check valve 4 is provided at the inlet to the chemical liquid mixing chamber 2 of No. 2, and the chemical liquid mixing chamber 3 is provided with an outlet 5 at the distal end thereof and communicates with the valve chamber 6. Injection control valve on the side
The injection pipe having a structure in which a discharge port 8 opened and closed by 7 and a liquid injection nozzle 9 is provided on the side wall thereof, and a drilling blade 10 is attached to the foremost part of the injection pipe 1 is provided by the present invention. It is preferably used when carrying out the method. The injection pipe 1 can be provided with a gas flow path for pressurizing the injection liquid or cutting liquid when the liquid is injected under high pressure.

The discharge port 8 is opened and closed by an injection control valve 7 described later, and is an outlet for injecting a drilling liquid or an injection liquid fed at a low pressure into the ground.

The liquid jet nozzle 9 is an outlet for jetting and injecting the injection chemical or cutting liquid fed at a high pressure into the ground, and a plurality of nozzles can be provided.

The injection control valve 7 has a function of controlling the switching of the chemical solution outlet. The injection control valve 7 opens the discharge port 8 while keeping the valve open in a pressure range lower than a preset pressure (low pressure), while a pressure range higher than the set pressure (high pressure). Then the valve closes and discharge port 8
Close. As a result, the drilling liquid or the liquid chemical for injection sent into the liquid chemical mixing chamber 3 at a pressure lower than the set pressure is mainly injected into the ground from the opened discharge port 8, while
The injection chemical or cutting fluid sent into the chemical mixing chamber 3 at a higher pressure than the set pressure is injected from the injection nozzle 9.

The operation mechanism of the injection control valve 7 is not particularly limited. For example, as shown in FIG. 1-B, a valve body 7-a urged by a spring 7-b receives a fluid pressure in the chemical liquid mixing chamber 3, and the valve body 7-b is actuated by the pressure. By moving -a, one that opens and closes the valve can be used. For example, a spring 7- having a strength that does not operate in a pressure range P _L lower than the set pressure.
state at the position of the energized valve body 7-a with b, opening the discharge port 8 in a state in which the valve is open (FIG. 1-B-1), whereas, the applied setting pressure than the pressure P _H Then, at the position of the valve element 7-a moved by the activated spring 7-b, the valve may be closed to close the discharge port 8 (FIG. 1-B-2). The pressure at which the injection control valve 7 operates does not need to be limited, but normally, the discharge port 8 is kept open in a range of less than 50 kg / cm ² , while the discharge port 8 is maintained in a range of 50 kg / cm ² or more. May be set to close.

[0029] A surfactant may be added to the cutting fluid or the chemical for injection to be injected by high-pressure injection in order to enhance the permeability into the ground and the mixing and mixing with the soil particles. Surfactants include the usual anionic, cationic, nonionic,
Various substances such as amphoteric can be used, and lignin sulfonate or its derivative, oxyacid salt, alkyl allyl sulfonate, polyoxyethylene alkyl ether, polyol complex, higher polyhydric alcohol sulfonate, melamine formalin condensation Reducing agents, dispersing agents, high-performance water reducing agents, fluidizing agents, etc., as cement admixtures containing sulfonic acid salts as main components. These usage, cutting fluid or infusion drug solution 1 m ³ per normal
0.1 to 50 kg, preferably 0.5 to 25 kg, more preferably 5
It is in the range of ~ 20kg. When the amount used is less than 0.1 kg, the effect of adding the surfactant is hardly recognized,
When the amount exceeds the above, the effect of the addition is not so much improved.

When switching between the cutting fluid to be injected or the chemical solution for injection, it may not be possible to switch in a short time due to the influence of the stagnation inside the injection pipe or the injection liquid transport pipe. It is preferable to switch the injection solution within a short time so as not to adversely affect the injection operation and the injection effect, and to confirm that the injection solution has been changed, before proceeding to the next step.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of the present invention and the apparatus used therein will be specifically described below. Note that the method and apparatus of the present invention are not limited to this. Example 1 In this example, as shown in FIG. 1, four independent flow paths 2-a, 2-b, 2-c and 2-d are provided, and the leading end of each flow path is filled. Chemical mixing chamber 3 provided at the tip of tube 1
Non-return valves 4-a, 2-b, 2-c and 4-d are respectively provided at the inlets of the respective channels to the chemical mixture chamber 3, and the chemical mixture chamber 3 is provided at the front end thereof. An outlet 5 is provided and communicates with a valve chamber 6. The valve chamber 6 has a discharge port 8 which is opened and closed by an injection control valve 7 at a tip end thereof, and a liquid injection nozzle on a side wall thereof.
9 was provided, and the injection pipe 1 having a cutting edge 10 at the foremost portion was used. The injection control valve 7 is opened when the fluid pressure in the chemical liquid mixing chamber 3 is less than 50 kg / cm ² ,
The operating pressure was set to 50 kg / cm ² by adjusting the operating strength of the spring 7-b for urging the built-in valve body 7-a so that the valve 7-a was closed when it was not less than / cm ² . .

1-0) Installation of chemical injection pipe in ground: injection pipe 1
Water is supplied as drilling fluid at a pressure of less than 50 kg / cm ² through the flow channel 2-a of the above, and the excavation is performed by rotating the injection pipe 1 while discharging the water into the sandy ground from the discharge port 8 to excavate the water at a depth of 15 m. The drilling water supply was stopped when it reached the ground.

1-1) Low pressure injection of chemical solution: flow path 2 of injection pipe 1
-b and 2-c are water-glass based chemicals "Nitroc 3"
(Nitto Kagaku Kogyo Co., Ltd., curing time 3 minutes) The main agent liquid and the curing agent liquid are fed at a pressure of 5 to 10 kg / cm ² and discharged into the ground from the discharge port 8 at a discharge speed of 30 l / min for 2 minutes. Upon injection, the drug solution flowed out from the gap between the injection pipe and the wall of the injection pipe insertion hole to the ground surface. Injected chemical solution into water glass "Nitrok No. 1" (Nitto Chemical Co., Ltd., curing time 3 seconds)
When the liquid was injected into the ground from the discharge port 8 at a discharge rate of 8 l / min, the chemical solution did not flow out to the ground surface after 2 minutes, but the injection pressure increased with the lapse of time.
After a lapse of minutes, the gauge pressure reached 15 kg / cm ² . Next, a water glass-based chemical “Nitroc 5
No. (Nitto Kagaku Kogyo Co., Ltd., curing time 90 minutes), and at a discharge speed of 6 l / min.
Retracted at a speed of 10 minutes, but the injection pressure was 20 kg gauge pressure
/ Cm ² , the drug solution injection was interrupted.

1-2) Cutting fluid high pressure injection injection processing: injection pipe 1
Using a high-pressure grout pump, a water glass-based chemical “Nitrok No. 5” (Nitto Kagaku Kogyo Co., Ltd., curing time adjusted to 120 minutes) was fed as a cutting fluid, and the injection pipe 1 was rotated. , Pressure 250kg / cm ² , discharge speed 20l /
In 1 minute, the injection nozzle 9 injects a 1m section from the depth of 15m to 14m in the ground every 30m for every 0.2m for 30 seconds, and the hardened body formed around the injection pipe is cut and collapsed.
The soil in the ground was cut, mixed and stirred.

1-3) Low-pressure injection of chemical solution: The above-mentioned water glass-based chemical "Nitrok No. 5" (curing time 90
) Was injected again, and injected at a discharge rate of 8 l / min from the discharge port 8 into a 1 m section in the ground from a depth of 15 m to 14 m. Injection pressure during the 60 minutes was maintained in the range of 5 to 10 kg / cm ^2. After the cutting fluid high-pressure injection treatment, a large amount of chemical solution could be permeated and injected over a long period of time, and a solid-sand compact (volume 1.65 m ³ ) with a large amount of consolidated soil could be formed. The uniaxial compressive strength of the obtained sediment compact is 5
It showed a value of 1010 kg / cm ² , which was sufficient strength for ground stabilization.

Comparative Example-1 The volume of the solidified earth and sand obtained by the chemical liquid injection treatment in Example 1-1-1) was 0.4 m ³ .

Example 2 The same injection tube as in Example 1 was used.

2-0) Installation of chemical injection pipe in ground: injection pipe 1
Water is fed as a drilling liquid at a pressure of less than 50 kg / cm ² through the flow channel 2-a, and the excavation is performed by rotating the injection pipe 1 while discharging into the sand ground mixed with the silt from the discharge port 8, and excavating to a depth of 10 m. When it reached the ground, the supply of drilling water was stopped.

2-1) Chemical outflow prevention body forming process: injection tube 1
Water glass chemical “Nitroc 5”
(Nitto Kagaku Kogyo Co., Ltd., curing time adjusted to 5 seconds) The main agent liquid and the curing agent liquid are fed using a high-pressure grout pump, and the pressure is applied while the injection pipe 1 is rotated.
Injection nozzle 9 at 200 kg / cm ² , discharge speed 20 l / min for 2 minutes
And injected into the ground. Next, the injection tube 1 is retracted by 1 m, and the same injection operation as described above is performed.
A substantially disk-shaped cured body was formed at each of the two positions m as a chemical liquid outflow preventive body. A chemical solution was injected into a region at a depth of 9 to 10 m in the ground sandwiched between the chemical liquid outflow preventers formed in advance by this process.

2-2) Low pressure injection of chemical solution (primary): injection tube
In the flow channels 2-b and 2-d of 1, the main agent liquid and the hardener liquid of the water glass type chemical solution “Enutite 10 H” (Nitto Kagaku Kogyo Co., Ltd., curing time 40 minutes) with a long curing time are applied at a pressure of 5 ~Ten
It was fed in kg / cm ^2, where the discharge speed 10l / min at the discharge port 8 tried injected into the region, but there was no leakage of the chemical liquid to the surface portion, the injection pressure is 30kg a gauge pressure / cm ² The injection of the drug solution was interrupted because it reached.

2-3) High-pressure injection of cutting fluid (primary):
Therefore, only the main liquid of the water glass-based chemical “Enutite 10 H” is fed as a cutting liquid using a high-pressure grout pump, and with the injection pipe 1 rotated, the pressure is 300 kg / cm ² ,
Depth in the ground from injection nozzle 9 at discharge rate 20 l / min 9.2
m was sprayed for 20 seconds, the hardened body formed around the injection pipe was cut and broken, and the earth and sand in the ground was cut, mixed and stirred.

2-4) Low-pressure injection of chemical solution (secondary):
According to the conditions described in 2-2) above, the drug solution `` Enutite 10
H "(hardening time: 40 minutes) was fed into the ground at a discharge speed of 10 l / min. The injection pressure was 10 kg / cm ² when the injection was restarted, but increased to 20 kg / cm ² when the injection was continued for 10 minutes, and the injection was interrupted because the discharge speed of the drug solution had decreased.

2-5) High pressure injection of cutting fluid (secondary):
Next, the injection pipe 1 is advanced to a position at a depth of 9.5 m, and only the hardener liquid of the above-mentioned chemical solution “Enutite 10 H” is fed as a cutting liquid. With the injection pipe 1 rotated, the pressure is 250 kg / c.
m ^2, and injected for 20 seconds at a position depth 9.5m in soil from the injection nozzle 9 at a discharge rate of 20l / min.

2-6) Low-pressure injection of chemical solution (third order):
According to the conditions described in 2-2) above, the drug solution `` Enutite 10
H "(curing time: 40 minutes) was fed, and injected at a discharge speed of 10 l / min from a discharge port 8 into a place at a depth of 9.5 m in the ground. The injection pressure was 8 kg / cm ² when the injection was restarted, but increased to 15 kg / cm ² when the injection was continued for 10 minutes, and the injection was interrupted because the discharge speed of the drug solution had decreased.

2-7) High-pressure injection of cutting fluid (Tertiary):
The injection pipe 1 is further advanced to a position at a depth of 9.9 m, and the above-mentioned chemical solution “Enutite 10 H” is fed as a cutting fluid.
With a pressure of 250 kg / cm ² and a discharge speed of 20 l /
In a minute, it was injected from the injection nozzle 9 into the ground at a depth of 9.9 m for 30 seconds.

2-8) Chemical solution low pressure injection process (fourth):
According to the conditions described in 2), the chemical solution "Enutite 10H"
(Curing time 40 minutes) and discharge at a discharge rate of 10 l / min
From 8 the water was injected into the ground at a depth of 9.9m for 30 minutes. The injection pressure was 5 kg / cm ² when the injection was restarted, and 10 kg at the end of the injection.
kg / cm ² .

In Example-2 in which the low-pressure injection processing of the chemical solution and the high-pressure injection injection processing of the cutting liquid are alternately performed, a large amount of the chemical liquid can be permeated and injected into the soil in the target area in the ground, A large amount of compacted soil (volume 1.6m ³ ) was able to be formed. The unconfined compressive strength of the obtained sediment compact showed a value of 3 to 8 kg / cm ² , which was sufficient strength for ground stabilization.

Comparative Example-2. The volume of the compacted earth and sand obtained by the chemical liquid injection treatment of Example-2 up to 2-2) was 0.16 m ³ .

[0049]

The present invention has the following effects. 1) In the conventional method, when the injection pressure of the chemical solution into the ground increases, the injection point is moved, and the injection amount of the soil stabilizer into the area to be stabilized in the ground is reduced. According to the method of the present invention, the injection amount of the chemical solution into the target region can be increased as compared with the method of the present invention. 2) A sufficient amount of the soil stabilizer is infiltrated and injected into the soil in the target area, and a large amount of compacted soil and high strength soil-sand compact can be formed. 3) Accordingly, the ground strength is increased, and the ground can be more safely and more reliably stabilized.

[0050]

[Brief description of the drawings]

1 shows an embodiment of an injection pipe device suitable for use in the method of the present invention, FIG. 1-A is an explanatory view showing the structure of an injection pipe, and FIG. 1-B is a discharge port by an injection control valve. It is explanatory drawing which shows the opening and closing state of.

[0051]

[Explanation of symbols]

 1 injection pipe, 2 flow paths, 3 chemical mixing chamber, 4 check valve, 5 chemical mixing chamber outlet, 6 valve chamber, 7 injection control valve, 8 discharge port, 9 liquid injection nozzle, 10 drilling blade,

Claims (2)

(57) [Claims] 1. A method for injecting a ground stabilizing chemical into a ground and hardening the same to form a solidified earth and sand, thereby stabilizing the ground. The injection of the chemical liquid is interrupted during the injection of the chemical liquid for chemical conversion, and after the high-pressure injection of the cutting liquid instead of the chemical liquid in the area, the chemical liquid for ground stabilization is further injected. Grout injection method. 2. The ground where the cutting fluid was injected before the injection of the cutting fluid.
Has a longer curing time than the curing time of the board stabilizing chemical
2. The method according to claim 1, wherein the liquid is a ground stabilizing solution.
Double grouting method.