JP2946061B2 - Compound grouting method and equipment used for it - 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 by using a soil stabilizer and an injection pipe device used for the method.

[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.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the above-mentioned problems of the prior art, to minimize the amount of chemical solution loss, to increase the amount of consolidated soil per unit amount of chemical solution injected, and to increase the strength. Safer and more compact soil
An object of the present invention is to provide a method for stably stabilizing the ground and an injection pipe device suitably used in this method.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies and carried out by appropriately combining the high-pressure injection method and the low-pressure injection method according to the area in the ground to be stabilized. It has been found that the object of the present invention can be achieved by solving the problems of the prior art.

A first invention provides a method for stabilizing a ground by injecting a ground stabilizing chemical into the ground and hardening the same to form a solidified earth and sand. A high-pressure injection of a chemical solution having a short curing time is applied to the ground-side region close to the region to be cured, and a cured body for preventing the outflow of the chemical solution to be injected later than the chemical solution is formed in advance, and then cured to the target region. The method comprises a double grouting method characterized by injecting and hardening a long-time chemical solution at a low pressure to form a solidified sediment.

The second invention provides a method for stabilizing a ground by injecting a ground stabilizing chemical into the ground and hardening the same to form a solidified soil and sand, wherein at least two independent flow paths 2 are provided. The distal end of each flow path 2 communicates with a chemical mixing chamber 3 provided at the distal end of the injection pipe 1, and the chemical mixing chamber of each flow path 2
A check valve 4 is provided at each of the inlets to the chemical liquid mixing chamber 3, and an outlet 5 is provided at the distal end of the chemical liquid mixing chamber 3 to communicate with the valve chamber 6, and the valve control chamber 6 has an injection control valve at its distal end. A discharge port 8 opened and closed by a nozzle 7 and a chemical solution injection nozzle 9 provided on a side wall thereof, and an injection pipe 1 having a drilling blade 10 at the foremost portion thereof is inserted and installed at a predetermined position in the ground. Then, a chemical solution with a short curing time, which has been sent into the flow path 2 at a pressure at which the discharge port 8 is closed, is applied to the ground surface area adjacent to the target area in the ground to be stabilized, from the injection nozzle 9 at a high pressure. After injection-curing and curing, a cured body for preventing the outflow of the chemical solution injected after the chemical solution is previously formed, the position of the injection pipe 1 is adjusted, and the discharge port 8 is opened in the target area. A chemical solution with a long curing time sent into the flow path 2 at a constant pressure is mainly injected from the discharge port 8 and cured. Thereby forming a sediment consolidation body and gist double grout grouting method ", wherein.

[0011] The third invention is directed to "having at least two independent flow paths 2 used for injecting the ground stabilizing solution into the ground, and the leading end side of each flow path 2 is an injection pipe 1. Each of the flow paths 2 has a check valve 4 at the inlet to the chemical mixing chamber 3, and the chemical mixing chamber 3 has an outlet 5 at its distal end. An injection pipe having an excavation blade 10 at the foremost end thereof, wherein the outlet 5 communicates with a valve chamber 6, and the valve chamber 6 has a discharge port which is opened and closed by an injection control valve 7 at the distal end thereof. 8 and a chemical solution injection nozzle 9 on the side wall thereof, and when the pressure of the fluid fed into the chemical solution mixing chamber 3 is lower than the set pressure, the discharge port 8 is opened by the injection control valve 7. On the other hand, when the pressure of the fluid is higher than the set pressure, the discharge port 8 is closed by the injection control valve 7. And gist injection tube device "to.

In the method of the present invention, as shown in FIG. 1, a chemical solution having a long hardening time is injected at a low pressure into a target region (referred to as an X region) in the ground to be stabilized, and the solution is reliably introduced into the soil. A hardened body S (hereinafter, referred to as a chemical outflow preventer) for preventing the outflow of a chemical solution having a long hardening time injected in a low-pressure injecting step in order to infiltrate into the low-pressure injecting step (hereinafter, referred to as a chemical outflow preventive body) is provided near the ground area (GL) near the X area. (Referred to as a Y region).
Therefore, when injecting the drug solution using the injection tube 1,
Prior to the low-pressure injection process for the X region, a high-pressure injection injection process is performed for the Y region to form a cured body S in advance, and then a chemical solution having a long curing time is injected into the X region at a low pressure to permeate the soil. And harden to form a compacted soil G.

One embodiment of the method of the present invention will be described with reference to FIG. First, a chemical solution having a short curing time is sprayed and injected at a high pressure into a Y region in the ground using an injection pipe 1 to be cured, and an outflow prevention body S for a chemical solution having a long curing time to be injected in a subsequent low-pressure injection step is formed in advance. (FIGS. 2-A, B, and C) Thereafter, a chemical solution having a long curing time is injected into the X region at a low pressure to be cured, thereby forming a solidified soil G (FIG. 2-D, E, and F).

As shown in FIG. 3, high-pressure injection and injection treatment is performed on two regions Y _{1 and} Y ₂ having different depths from the ground surface to form chemical liquid outflow preventers S ₁ and S ₂ . Thereafter (FIGS. 3-A, B, C, and D), low-pressure injection processing is performed on the X region sandwiched between these chemical liquid outflow preventers to form a solid sediment G (FIGS. 3-E and F). Can also.

As shown in FIG. 4, in the high-pressure injection injection step in the same injection hole, target areas (X _1, X _2, ..., X ₁₎ of different depths from the ground surface side in the ground to be stabilized.
_n ) corresponding to each surface area (Y _1, Y _2, …,
Y _n ) is sequentially injected with a high-pressure chemical and cured, and a plurality of chemical outflow preventers (S _1, S _2, ..., S _n ) are provided in the same injection hole.
Previously was formed (Fig. 4-A, B, C, D, E), then the first sequence from the region X ₁ corresponding to the region Y ₁ where the chemical was injected implanted, region X _2, ..., with respect to X _n It is also possible to perform the chemical injection in the low-pressure injection step by using the method (FIG. 4-F, G).

As shown in FIG. 5, a plurality of chemical liquid outflow preventive members are formed in advance by performing high-pressure injection / injection processing sequentially from the deep region to the region closer to the ground surface, contrary to FIG.
(FIGS. 5-A, B, C, D, and E) Then, low-pressure injection processing is performed on each of the X regions sandwiched between the chemical liquid outflow preventers to form sediment-solids G (FIG. 5-F). , G) can also be used. The method shown in FIG. 4 is preferable from the viewpoint of the effect of injecting the chemical solution into the soil by low-pressure injection, and the method shown in FIG. 5 is preferable from the viewpoint of construction.

When the section to be improved for ground stabilization extends over a long distance, the processing for forming the chemical liquid outflow preventive body by high-pressure injection and the processing for forming the compacted soil by low-pressure injection are repeated at different depths. Just do it. For example, as shown in FIG. 2, the Y region adjacent to the X region is subjected to a high-pressure injection / injection process to form a chemical solution outflow prevention body S, and then the X region is subjected to a low-pressure injection process to perform a sediment consolidation G
And a method of alternately repeating the high-pressure injection injection process and the low-pressure injection process by sequentially changing the depth, a method of sequentially repeating the process shown in FIG. 3 by changing the depth, and FIG. 4 or FIG. As shown in, for the section to be improved, after changing the depth at appropriate intervals and sequentially forming a plurality of chemical solution outflow prevention bodies by performing high pressure injection processing, each was sandwiched between two chemical solution outflow prevention bodies A method of sequentially performing low-pressure injection processing on each X region to form a sediment-solidified body G may be used. In consideration of various conditions, by performing a chemical solution injection treatment by selecting an appropriate method from the various aspects as described above, the chemical solution is more reliably introduced into the soil in the target area in the ground. The soil can be infiltrated to form a compacted soil with a large amount of consolidated soil, thereby stabilizing the ground.

It is preferable that the chemical outflow preventive formed in the high-pressure injection and injection step is a substantially disc-shaped cured body. The thickness of the chemical solution outflow preventing body may be any thickness as long as the effect of preventing the chemical solution from flowing out for a long curing time in the low-pressure injecting step is prevented. Such a thickness is usually in the range of 1 to 50 cm as an average thickness. When the thickness is less than 1 cm, the effect of preventing the outflow of the chemical solution having a long curing time is small, the loss amount of the injected chemical solution increases, and the stabilization of the ground becomes uncertain. On the other hand, even if the thickness exceeds 50 cm, the effect of preventing the outflow of the chemical in the low-pressure injection step does not increase so much, and the amount of the chemical used in the high-pressure injection and injection step increases, which is not advisable. The larger the diameter of the chemical outflow preventing body is, the more desirable it is, and the average diameter is at least 0.5 m or more, usually 1 m or more, preferably 2 m or more.

In the high-pressure injection / injection step, when a chemical solution is injected into the ground to cut the ground, and when the chemical solution and the soil particles are agitated and mixed, a disk-shaped cured body having a diameter as large as possible is provided around the injection pipe. Injection injection is performed while rotating the injection tube to form it. The rotation of the injection tube can be continuous or intermittent and can be stopped. In general, in a high-pressure injection injection method, a columnar soil-solid compact can be formed by injection injection of a chemical solution while moving an injection pipe forward and backward. However, according to the method of the present invention, it is not necessary to form a columnar compact in the high-pressure injection and injection step as in the prior art. In the high-pressure injection / injection step in the method of the present invention, it is only necessary to rotate the injection pipe at a fixed depth during the injection injection, and it is not particularly necessary to advance or retract the injection pipe. In particular, when it is desired to form a thick disk-shaped cured body, the injection pipe may be moved forward and backward during injection injection.

The injection pressure of the chemical in the high-pressure injection injection step is usually 50 to 1000 kg / cm ² , preferably 100 to 600 kg / cm ² .
cm ² , more preferably in the range of 150 to 500 kg / cm ² . If the injection pressure is less than 50 kg / cm ^2, it takes a long time to cut the ground, and if it exceeds 1000 kg / cm ² , the loss of the chemical solution increases.

The chemical used in the high-pressure injection / injection step preferably has a short curing time. If the curing time is long, the chemical in the low-pressure injection step is injected before the chemical outflow preventing body is formed, and the effect intended by the present invention cannot be obtained in such a state. "Chemical solution with short curing time" used in the method of the present invention
The term “hardening time” refers to a curing time in which a cured body is quickly formed after the injection of the chemical solution by the high-pressure injection, and the process can proceed to the injection of the chemical solution by the low-pressure injection.

When the method shown in FIG. 4 or FIG. 5 is used, after the high-pressure injection is completed as shown in FIG. A chemical solution having a relatively long curing time can be used. Therefore, the short curing time referred to in the present invention refers to a time period for substantially curing before the chemical solution is injected in the low-pressure injection step.

As the chemical solution used in the high-pressure injection and injection step in the method of the present invention, a liquid such as Portland cement or mixed cement having a hardening time of more than 6 hours can be used, but the hardening time is preferably within 1 hour. ,
More preferably, the time is within 10 minutes. In the most preferred embodiment, the curing time of the liquid medicine to be injected is adjusted to about 10 minutes or less at the initial stage of the start of injection, and the curing time is gradually advanced with the elapse of the injection time, and 10 seconds at the stage when the injection is completed. The following method is used for instantaneous connection. According to this method, it is possible to immediately shift to the chemical injection by the low-pressure injection after the completion of the chemical injection by the high-pressure injection.

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 that the curing time is long enough so that the curing time is not lost. The chemical used in the low-pressure injection step in the method of the present invention includes a curing time of usually 30 seconds or more, preferably 1 minute or more, more preferably 10 minutes or more, and most preferably 60 minutes or more. A slow-setting type that cures in about 2 days is suitable. In addition,
Although a chemical solution having a curing time of about one week can be used, too long one is not preferable because the curing is insufficient and the gel strength is low.

In the same injection hole, the chemical outflow prevention body
_{(S 1, S 2, ...} , S n) interval is not particularly necessary to limit, typically 0.1～3M, preferably 0.2～2M, more preferably it is preferable in the range of 0.5-1 m. If it is less than 0.1 m, fine treatment can be performed, but frequent switching of the chemical solution is required, and the operation becomes complicated. Although it can be constructed even with a length of 3 m or more, if the distance between the chemical liquid outflow preventers is long, the partition effect is reduced, and the amount of solidified soil in the target area is undesirably reduced.

In the low-pressure injection process, the injection tube is continuously or intermittently rotated and moved backward or forward, or the liquid medicine is injected in a stationary state. In each of the injection steps, a predetermined amount of the chemical solution can be injected continuously or intermittently and divided, and it is preferable to perform the injection by appropriately selecting according to the state of the ground.

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. In the method of the present invention, the chemicals used in the high-pressure injection processing and the low-pressure injection processing may be the same or different. 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, silicic acid colloid solution, destabilized silicic acid aqueous solution, activated silicic acid aqueous solution, etc.);
Urea-formaldehyde condensate type / acrylamide type
Methylol acrylamide-based, acrylate-based, methacrylate-based, urethane resin-based, polyethylene glycol dimethacrylate-based, and polyethylene glycol diacrylate-based polymer soil stabilizers. 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 amount may be appropriately adjusted so as to obtain a desired curing time.

The high-pressure injection or low-pressure injection in the method of the present invention may be performed in accordance with the high-pressure injection or low-pressure injection, which is carried out by the ordinary chemical liquid injection method. In addition, when the chemical solution is switched, it may not be switched in a short time due to the effect of the chemical solution remaining inside the injection tube or the chemical solution transport tube. It is preferable to switch the chemical solution within a short period of time so as not to adversely affect the injection operation and the injection effect, and confirm that the switching has been performed, and then proceed to the next step.

The injection tube 1 of the present invention has at least two independent flow paths 2 as shown in FIG.
The tip side of the drug solution mixing chamber 3 provided at the tip of the injection tube 1
A check valve 4 is provided at the inlet of each flow path 2 to the chemical mixing chamber 3, and the chemical mixing chamber 3 is provided with an outlet 5 at the distal end thereof and communicates with the valve chamber 6. The valve chamber 6 is provided with a discharge port 8 opened and closed by an injection control valve 7 on the tip side, and a chemical solution injection nozzle 9 on the side wall thereof. It has an attached structure.
An injection tube having such a structure is suitably used when performing the method of the present invention.

The injection pipe (1) has at least two independent flow paths (2) for a chemical solution, and may be a multi-tube type or a multi-tube type, and the structure thereof is not particularly limited. In the method of the present invention, at least two types of chemicals, one having a long curing time and one having a short curing time, are appropriately switched and used. When a chemical solution prepared to cure in a short time is sent into the injection pipe, the chemical solution gels in the injection pipe before being injected into the ground, and the generated gel accumulates in the injection pipe and blocks the flow path, It interferes with infusion of chemicals. In order to prevent this, in the method of the present invention, the chemical solution having a short curing time includes the base solution (A
Liquid) and a curing agent liquid (liquid B) using a two-part curable chemical liquid, and the liquid A and liquid B are mixed immediately before being injected into the ground. To cope with this, it is preferable that the injection pipe used in the method of the present invention has at least two independent flow paths for the chemical solution.

In the case where the curing time is adjusted by adjusting the mixing ratio of the liquid A and the liquid B to be combined, or in the case where the liquid A is fixed and the liquid B combined with the liquid is one corresponding to the length of the curing time. In the case where the liquid is prepared separately and is appropriately selected and supplied according to the desired curing time to be mixed with the liquid A, the number of channels of the chemical liquid may be two. Also, A
The solution is fixed, while the solution B is prepared by supplying at least two kinds of liquids corresponding to the length of the curing time, supplying them to dedicated flow paths and mixing them with the liquid A, and has at least three chemical liquid flow paths. I do. In addition, two types of liquid A and liquid B respectively
In a system in which liquids are prepared, and four types of liquids are supplied to dedicated flow paths and mixed, the number of flow paths for the chemical liquid is at least four.

The drilling liquid used for inserting and installing the injection pipe into the ground may be supplied using a part or all of the channel (2) for the chemical liquid.

Each of the flow paths (2) has an injection pipe
(1) communicates with the chemical mixing chamber (3) provided at the tip end.
The chemical liquid mixing chamber (3) is provided to stir and mix the liquid A and the liquid B fed through each flow path (2) to obtain a liquid chemical for injection having a uniform composition. The size and structure of the chemical mixing chamber (3) are not particularly limited, and the residence time required to make the composition of the injection chemical uniform can be obtained, and the curing time of the injection chemical whose residence time is adjusted is reduced. It is sufficient that the volume does not exceed the limit, and a usual stationary in-pipe mixing device can be used.

If used for a long time for injecting a drug solution, a gel may adhere to the inside of the drug solution mixing chamber (3). In order to prevent this, it is preferable that the liquid contact portion in the chemical liquid mixing chamber (3) is provided with a synthetic resin lining, and that the interior members such as the mixing element are made of synthetic resin.

A check valve (4) is provided at the inlet of each channel (2) to the chemical liquid mixing chamber (3). The check valve (4) prevents chemicals and water from flowing back into the flow path (2) from the chemical liquid mixing chamber (3), and mixes different types of chemicals in the flow path (2) to form a gel. It is provided to prevent the inside of the injection tube from being closed or to prevent the chemical solution from being diluted with water to change the performance of the chemical solution. Check valve
For (4), a spring type or a ball valve type can be used.

After the chemical solution injection operation is completed, water is fed into the mixing chamber for washing, especially in order to prevent the chemical solution remaining in the mixing chamber from gelling in the mixing chamber. It is preferable that a dedicated flow path for the cleaning water is provided in communication with the mixing chamber separately from the flow path for the chemical solution, and the cleaning liquid is washed with as little water as possible to reduce the dilution of the chemical solution with water. Therefore, it is preferable that the number of flow paths (2) provided in the injection pipe is the sum of the flow path of the chemical solution and the flow path of the washing water. The chemical mixing chamber is also provided in the washing water flow path (2).
A check valve (4) is provided at the entrance to (3).

The chemical liquid mixing chamber (3) is provided with an outlet (5) at its distal end and communicates with the valve chamber (6). The valve chamber (6) is opened and closed by an injection control valve (7) at its distal end. A discharge port (8) is provided, and a chemical solution injection nozzle (9) is provided on a side wall thereof. The discharge port (8) is an outlet that is opened and closed by an injection control valve (7) to be described later, and that injects a drilling liquid or an injection liquid supplied at a low pressure into the ground.

The injection tube (1) of the present invention has a chemical mixing chamber (3).
At least one chemical liquid spray nozzle (9) is provided on the side wall of the valve chamber (6) provided on the outlet side of the valve. Chemical injection nozzle
(9) is to inject the chemical solution sent at high pressure into the ground to cut the soil and simultaneously mix and mix the chemical solution and the soil particles to form a nearly disk-shaped cured body in the ground. Is provided.

The injection control valve (7) has a function to control 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 (low pressure) lower than a preset pressure, while the pressure range is higher than the set pressure. At high pressure, the valve closes and closes the discharge port (8). As a result, the drilling liquid or the liquid for injection sent into the chemical liquid 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 pressure is lower than the set pressure. The injection chemical liquid sent into the chemical liquid mixing chamber (3) at high pressure is injected from the injection nozzle (9).

The operating mechanism of the injection control valve (7) is not particularly limited. For example, as shown in FIG. 6-B, the valve element (7-a) urged by the spring (7-b) receives the fluid pressure in the chemical liquid mixing chamber (3) and operates by the pressure.
The one that opens and closes the valve by moving the valve element (7-a) in (7-b) can be used. For example, at the position of the valve element (7-a) urged by the spring (7-b) having a strength that does not operate in the pressure range P _L lower than the set pressure, the discharge port ( 8) Open (Fig. 6-B-
1), whereas, in the state that joined the set pressure or more pressure P _H, the valve element moved by the actuated spring (7-b) (7
In the position -a), the valve may be closed to close the discharge port (8) (FIG. 6-B-2). The pressure at which the injection control valve (7) operates is not particularly limited, but is usually 50 kg.
/ Cm ² range keeps the outlet (8) open,
On the other hand, in the range of 50 kg / cm ² or more, the discharge port (8) may be set so as to close.

The excavating blade (10) cuts the ground when inserting the injection pipe (1) into the ground, and may use a normal bit for excavating the ground.

[0042]

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. 6, 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. It communicates with a chemical solution mixing chamber 3 provided at the tip of the pipe 1,
A check valve 4- is provided at the inlet of each channel to the chemical mixture chamber 3.
a, 2-b, 2-c and 4-d are provided, and the chemical liquid mixing chamber 3 is provided with an outlet 5 at its distal end and communicates with the valve chamber 6, and the valve chamber 6 is controlled for injection at its distal end. Discharge port opened and closed by valve 7
In addition, a liquid injection nozzle 9 was provided on the side wall of the injection pipe 9, and an injection pipe 1 having a cutting blade 10 at the foremost part was used. The injection control valve 7 has a fluid pressure in the chemical mixing chamber 3 of 50 kg.
/ Cm ² , the valve element 7-a is installed to be open when it is less than 50 kg / cm ² and closed when it is 50 kg / cm ² or more.
The operating pressure of the spring 7-b for biasing the pressure was adjusted to 50 kg / cm ² by adjusting the operating strength.

1-1) Installation of chemical injection pipe in the ground: (FIG. 5-A
Water is supplied as drilling fluid at a pressure of less than 50 kg / cm ² through the flow path 2-a of the injection pipe 1 and excavation is performed by rotating the injection pipe 1 at a high speed while discharging the water from the discharge port 8 into the ground. Then, when it reached the ground at a depth of 10 m, the supply of drilling water was stopped.

1-2) High-pressure injection / injection processing: (FIGS. 5-B, C, D, and E)
With the injection pipe 1 rotated at a low speed, an ultra-high pressure grout pump is used to feed a cement-based chemical "CCP5" (Nitto Chemical Co., Ltd., curing time 2 minutes 30 seconds) into the flow path 2-b with a short curing time. It was injected into the ground from the injection nozzle 9 at a pressure of 300 kg / cm ² and a discharge speed of 65 l / min, and 300 l was injected.
Next, the chemicals were switched, and a water glass-based chemical “Nitrok No. 5” (Nitto Chemical Co., Ltd., with a hardening time adjusted to 5 seconds) was fed into the flow channel 2-c, and the pressure was 220 kg / cm ² , At a discharge speed of 50 l / min, it is injected into the ground from the injection nozzle 9 and 200
1 was injected (FIG. 5-B, C). Next, the injection tube 1 is retracted by 3 m, and the same injection operation as described above is performed (FIG. 5-D). Further, the injection tube 1 is retracted by 3 m, and the same injection operation is repeated again. Formed a disk-shaped cured body
(FIG. 5-E). Thereafter, via the flow path 2-a, the chemical mixture chamber 3
Then, 1 l of washing water was fed and discharged, and the high-pressure injection / injection step was completed, and the process was shifted to a low-pressure injection step.

1-3) Low-pressure injection treatment: (See FIGS. 5-E, F and G). The injection pipe 1 is advanced to a depth of 9.9 m, and a water glass-based chemical “N "Tight Seven" (Nitto Chemical Co., Ltd., curing time 190 minutes) at a pressure of 5 to 10 kg / cm
² and the injection pipe 1 is retracted at a speed of 1.2 cm / min and discharged from the outlet 8 into the ground at a discharge speed of 5 to 15 l / min.
2.8 m ³ was injected (FIGS. 5-E, F). Next, the injection pipe 1 was retracted to a position at a depth of 6.9 m, and 2.8 m ³ of the chemical solution was injected by performing the same operation as above (FIGS. 5-F, G). After that, channel 2-
1 l of washing water was fed into and discharged from the chemical solution mixing chamber 3 via a, and the low pressure injection step was completed. In this embodiment, the liquid medicine injection amount total 7.1 m ^3, a volume 16.6 m ³ (length of about 6 m,
A soil compact having an average diameter of about 1.9 m) and a uniaxial compressive strength of ^{2 to 3} kg / cm ² was obtained.

COMPARATIVE EXAMPLE-1 The volume of the sediment compact obtained by injecting the same amount of the chemical solution as in Example-1 only by the high-pressure injection method of Example-1 was 7.5.
m ³ (average diameter about 1.2 m).

Comparative Example-2. The volume of the soil-solid compact obtained by injecting the same amount of the chemical solution as in Example-1 only by the low-pressure injection method performed in Example-1 was 11.5 m ^3.
(Average diameter about 1.6m). According to the method of the present invention, the amount of solidified soil per injected chemical amount could be greatly increased as compared with the case where the chemical solution was injected only by the high-pressure injection injection system or only the low-pressure injection system. .

[0048]

The present invention has the following effects. 1) Compared with the conventional method using only the high-pressure injection method, the amount of the soil stabilizer used for the high-pressure injection method can be reduced to a small amount, and the loss amount of the chemical solution can be greatly reduced. 2) The chemical outflow prevention body formed by high-pressure injection prevents the escape of the chemical that is injected at the subsequent low pressure and has a long hardening time, so the loss of the chemical is small and the soil to the soil in the target area in the ground can be prevented. The permeation and injection of the chemical solution is performed efficiently, and a compacted soil with a large amount of compacted soil can be formed. 3) The loss amount of the soil stabilizer is small as a whole, and the soil consolidation efficiency per unit amount of the injected soil stabilizer is large.

[0049]

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a first example of an embodiment of the method of the present invention.

FIG. 2 is an explanatory diagram showing a construction order of a first example of an embodiment of the method of the present invention.

FIG. 3 is an explanatory view showing a construction order of a second example of the embodiment of the method of the present invention.

FIG. 4 is an explanatory view showing a construction order of a third example of the embodiment of the method of the present invention.

FIG. 5 is an explanatory view showing a construction order of a fourth example of the embodiment of the method of the present invention.

6 shows an embodiment of the injection tube device of the present invention, FIG.
FIG. 6A is an explanatory diagram showing the structure of the injection pipe, and FIG. 6B is an explanatory diagram showing the open / closed state of the discharge port by the injection control valve.

[0050]

[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 chemical injection nozzle, 10 drilling blade,

Claims (3)

(57) [Claims] In a method for injecting a ground stabilizing chemical into the ground and hardening the same to form a solidified earth and sand and to stabilize the ground, a method for stabilizing the ground close to a target area in the ground to be stabilized. A chemical solution having a short curing time is injected into the ground surface side by high-pressure injection and cured to form a cured body for preventing the outflow of the chemical solution to be injected later than the chemical solution, and thereafter, the chemical solution having a long curing time is applied to the target region. A double grouting method characterized by injecting and hardening under low pressure to form a compacted earth and sand. 2. A method for injecting a ground stabilizing chemical into the ground and hardening the same to form a sediment-solidified body, thereby stabilizing the ground, comprising at least two independent flow paths 2,
The distal end side of each flow path 2 communicates with a chemical mixing chamber 3 provided at the distal end of the injection pipe 1, and a check valve 4 is provided at the inlet of each flow path 2 to the chemical mixing chamber 3, respectively. The chemical liquid mixing chamber 3 is provided with an outlet 5 at its distal end and communicates with a valve chamber 6, and the valve chamber 6 has a discharge port opened and closed by an injection control valve 7 at its distal end.
8 and a chemical solution injection nozzle 9 on the side wall thereof, and an injection pipe 1 having a drilling blade 10 at the foremost portion thereof is inserted at a predetermined position in the ground so as to be stabilized. A chemical solution having a short curing time fed into the flow path 2 at a pressure at which the discharge port 8 is closed is hardened by high-pressure injection injection from the injection nozzle 9 into the ground side area adjacent to the target area in the ground to be hardened,
After a cured body for preventing the outflow of the drug solution to be injected after the drug solution is formed in advance, the position of the injection pipe 1 is adjusted, and the outlet port 8 is opened to the flow path 2 at a pressure at which the discharge port 8 is opened. A double grouting method characterized by injecting and hardening a chemical solution that has been sent for a long time, mainly from the discharge port 8, to form a solidified earth and sand. 3. At least two independent flow paths 2 used for injecting a ground stabilizing chemical into the ground, and the front end side of each flow path 2 is provided at the front end of an injection pipe 1. A check valve 4 is provided at the inlet of each flow path 2 to the chemical mixing chamber 3, and the chemical mixing chamber 3 is provided with an outlet 5 at the distal end thereof. Drilling blade at tip
An injection pipe having an outlet 5, which communicates with a valve chamber 6; a discharge port 8 which is opened and closed by an injection control valve 7 at its distal end; An injection nozzle 9 is provided, and when the pressure of the fluid fed into the chemical liquid mixing chamber 3 is lower than the set pressure, the discharge port 8 is opened by the injection control valve 7, while the pressure of the fluid is higher than the set pressure An injection pipe device, wherein the discharge port 8 is sometimes closed by an injection control valve 7.