JP2000273859A - Chemical grouting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a concentrically cylindrical improved body by infiltration grouting and a large improved body having a diameter of about 5 meters. SOLUTION: The ground for construction work is digged down to a predetermined depth to form an insertion hole 31, a grouting external pipe having a plurality of packers 6, 6 at an interval in the axial direction in an outer face part and grouting ports 7 between adjacent packers 6 and 6 is relatively inserted into the insertion hole 31, and both adjacent packers 6, 6 are inflated and adhere closely to a wall face of the insertion hole 31. While a region surrounded by adjacent packers 6, 6, the wall face of the insertion hole 31, and an outer face of the grouting external pipe is used as a space, and while the space is filled with chemical liquid through the grouting port 7, chemical liquid is grouted into sand or sand and gravel ground at a grouting speed of above 10 liters/min and below 40 liters/min.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemical liquid injection method for improving a ground.

[0002]

2. Description of the Related Art This type of construction method and apparatus are mainly used in Showa 4
Many improvements have been made in the late 1950s and 1975. Typical examples still in use are the rod injection method, the strainer injection method, and the double pipe double packer injection method.

[0003] Among them, the double-pipe double-packer injection method is excellent in that reliable infiltration can be performed.

In the injection of a double pipe double packer, a target ground is excavated to a predetermined depth to form an insertion hole, and an injection pipe for double pipe double packer injection (including an outer pipe and an inner pipe) is formed in the insertion hole. ).

However, a clearance is formed between the insertion hole and the injection pipe, and when the chemical is injected, the chemical flows out to the ground. Therefore, the clearance is previously filled with a cement bentonite filler. The chemical is injected into the ground while the cement bentonite filler is split by the pressure of the chemical.

[0006]

Therefore, the chemical liquid obtained by splitting the cement bentonite filler is permeated and injected only through a very small area in contact with the ground corresponding to the wall surface of the insertion hole.

[0007] For this reason, when the injection speed is increased, the ground exceeds the permeation permissible speed at which the chemical solution is also received, and splitting occurs in the ground, so that a concentric cylindrical improved body centering on the axis of the insertion hole cannot be formed. , Is often injected into loose parts of the ground. As a result, the improvement is generally elliptical. Incidentally, the permeation permissible speed is generally about 10 l / min in sandy ground.

A main object of the present invention is to form a concentrically improved cross-section by permeation injection, and to form a large-sized improved spherical member having a diameter of about 5 m at each stage of injection. . When the improved body is connected or connected in the axial direction, a cylindrical improved body having a diameter of about 5 m can be formed.

[0009]

The present invention which has solved the above-mentioned problems is as follows. <Invention according to claim 1> The target ground is excavated to a predetermined depth to form an insertion hole, and a plurality of packers are provided on an outer surface at intervals in an axial direction, and an injection port is provided between adjacent packers. The outer tube having an injection is relatively inserted into the insertion hole, and the two adjacent packers are swelled and brought into close contact with the wall surface of the insertion hole. With the enclosed area being a space, while filling the space with the drug solution from the inlet, 10
A chemical liquid injection method characterized by injecting into sandy or gravel ground at an injection speed of more than 40 liters / minute and not more than 40 liters / minute.

<Invention according to claim 2> The injection is performed by using an outer injection tube having injection ports at a plurality of axially spaced sites and an inner injection tube which can be inserted into and moved into the outer injection tube. 2. The chemical solution injection method according to claim 1, wherein the inner tube is moved in the axial direction within the outer tube for injection, and a medical solution is injected from different inlets through different inlets.

<Invention of Claim 3> A through-hole is formed in the outer tube for injection, and the packer is provided so as to straddle the through-hole in the axial direction, and the front and rear ends of the packer in the axial direction are connected to the outer tube for injection. 3. The packer is sealed in a liquid-tight manner, and a swelling fluid is sent into the packer through the through-hole to expand the packer.
Chemical solution injection method described.

<Invention according to claim 4> A through hole is formed in the outer injection tube, a deformable sleeve is provided to cover the through hole, and the packer is provided across the sleeve in the axial direction. Using the packer whose front and rear ends in the axial direction are liquid-tightly sealed in an outer filling tube, the swelling fluid is fed through the through-hole, and the sleeve is deformed at the time of the feeding, thereby causing the swelling fluid to flow. 3. The chemical liquid injection method according to claim 2, wherein the packing is bulged by flowing into the packer, and in a completed flow state, the sleeve is restored to close the through-hole.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the embodiments shown in the drawings. <Example of Injecting Apparatus> First, the injecting apparatus will be described. FIG. 1 shows an outer tube 10, in which a through hole 4 is formed in a wall surface of the first tube 1, and a rubber or the like which can be deformed to cover the through hole 4. A flexible sleeve 5 is provided. Across the sleeve 5, the front and rear portions in the axial direction are made of rubber or the like which is sealed in a liquid-tight manner with the second tube 2 and the third tube 3 screwed with the first tube 1, respectively. A flexible packer 6 is mounted.

As shown in FIG. 3, the outer tube 10 is prepared as a unit tube, and the second tube 2 of the unit tube and the third tube 3 of the other unit tube are screwed and connected to be long. The outer tube of the injection.

In the case of a continuous injection outer tube, a plurality of, for example, three or more, packers 6 are mounted on the outer surface at intervals in the axial direction. Further, an inlet 7 is formed in the third pipe 3 between the adjacent packers 6, 6, as shown in FIG. As shown in FIG.
For example, a total of 16 stages can be formed in four stages at 90-degree intervals in each stage. It is desirable that these injection ports 7, 7,... Adopt means for preventing sand particles from entering the surrounding ground.
As shown in (1), it is possible to adopt a mode of covering with a flexible sleeve 8 made of rubber or the like, or covering each step or the whole with a film made of, for example, vinyl chloride which is broken by the supply pressure of the chemical solution.

On the other hand, as shown in FIG. 1, an inner tube 20 for injection is prepared. The injection inner tube 20 is not limited as long as it can be inserted into the outer tube 10, as long as the inner and outer surfaces of the outer tube 10 are in close contact with the front and rear of the discharge port 22 in a liquid-tight manner and pump the chemical solution into the inside. In addition to simply providing rubber and other packer members 23 and 24 before and after a discharge port 22 of an inner pipe main body 21 having a chemical solution supply path,
What is shown in FIG. 4 of 44893 can be used as it is.

<First Construction Example> When construction is performed using such an injection device, first, as shown in FIG. 2, the target ground 30 is excavated to a predetermined depth to form an insertion hole 31. In this case, it is desirable to drill using the casing 50 to prevent the insertion hole 31 from collapsing.

Then, the outer tube for injection 10 is inserted into the insertion hole 31.

Thereafter, the casing 50 is used to insert the insertion hole 3.
If a 1 is formed, remove it. This allows
The outer injection tube 10 is relatively inserted into the insertion hole 31. Since the outer injection tube 10 can be built directly or together with the casing 50, in this sense the outer injection tube 10
Is used in the present invention.

Thereafter, the discharge port 22 is placed at the position of the packer 6.
In the state where the through hole 4 of the packer 6 and the discharge port 22 are in communication with each other, the swelling fluid 40, preferably a solidifying material such as cement or cement bentonite, is passed through the flow path in the injection inner pipe 20. And the like are sent under pressure to the inside of each of the adjacent packers 6, 6 so that these packers 6, 6 are bulged and adhere to the wall surface of the insertion hole 31.

When the swelling fluid 40 is fed, other suitable means can be used in addition to discharging the fluid from the discharge port 22 through the internal flow path using the injection inner tube 20 as described above. In any case, the swelling fluid 40 passes through the through-hole 4 and deforms the sleeve 5 by the feed pressure. For example, the sleeve 5 is inserted into the packer 6 while separating both ends of the sleeve 5 from the outer surface of the first pipe 1. Sent in. When the packer 6 has swelled sufficiently, the feeding of the swelling fluid 40 is stopped. Then, the sleeve 5 is restored and the through hole 4 is restored.
Is sealed. The swelling of the packer 6 may be performed at least in the adjacent packers 6, 6, but if necessary, all of the target packers may be sequentially swelled.

If the setup is completed, or if the inner tube 20 is used for feeding the swelling fluid 40, the inner tube 20 is inserted into the outer tube 10 and the packers 6, 6 are removed. In the operated state, the injection inner tube 20
In place of the swelling fluid 40, a chemical is pumped out and discharged from the discharge port 22, and through the inlets 7, 7,... And infiltrate into it.

When injecting the chemical, preferably, the inner tube 20 is inserted to the deepest portion of the outer tube 10, and after the adjacent packers or all the packers are bulged as described above, the inner tube 20 is injected. It is desirable that the corresponding inlets 7, 7,. Conversely, a step-down method from the upper part to the deepest part, or a method of moving up and down in an appropriate selection position order can be adopted.

In this case, unlike the conventional method in which the cement bentonite filler is filled in advance and the chemical liquid is injected into the ground while splitting the cement bentonite filler by the pressure of the chemical liquid, as shown in FIG. As described above, the region surrounded by the adjacent packers 6, 6 and the wall surface of the insertion hole 31 and the outer surface of the injection outer tube 10 is a space where no filler is present.
The chemical liquid G injected through the inlets 7, 7,... Is injected into the ground 30 between the adjacent packers 6, 6 while being filled in a relatively large space.

Therefore, the insertion hole 31 facing the space
It has been found from the results of experiments that the water penetrates into the ground 30 from the entire surface of the ground without penetrating even if the injection speed is high. As a result, it became possible to inject a large amount of chemical solution from one injection zone, and it was found that the chemical solution that had permeated the ground was permeated and injected far away. As a result of the experiment, an injection diameter of about 5 m was obtained.

As the chemical, it is preferable to use a water glass-based chemical, particularly a silica sol-based chemical, from the viewpoint of permeation injection.
The gel time in the soil is preferably about 1 to 10 hours. The injection speed (permeation permissible speed as viewed from the ground) can be injected up to about 40 liters / minute.

As the fluid for swelling the packer, water or air can be used in addition to cement bentonite. However, in the case of cement bentonite, it hardens soon, and the packer 6 is firmly attached to the wall surface of the insertion hole 31. This is preferable in that it can be closely attached. The dimension between the packers 6 and 6 is 10 cm to 2 m, particularly preferably 25 to 50 cm.
Degree.

As shown in FIG. 7, it is preferable that the total length of the dimensions between the packer 6 and the packers 6 and 6 substantially coincides with the target diameter of the improved body Z (for example, about 5 to 6 m).

<Second Construction Example> The present invention is particularly effective as a liquefaction countermeasure method and a method for strengthening the ground in a substantially uniform sandy ground in a seaside area. The ground is, for example, as shown in FIG. In addition, when a gravel layer or the like is included, there is a possibility that the chemical solution escapes through the gravel layer having a higher hydraulic conductivity. Therefore, the main packer 6 is divided into divided packers 6A, 6A with the middle or the center of the main packer 6 interposed therebetween, and a sub-injection port 7A is formed therebetween. After swelling, cement bentonite or a flash binder showing a gel time of several seconds to several minutes is injected from the sub-injection port 7A, roughened into the gravel layer, and subsequently, a chemical solution is injected from the main injection port 7, A uniform improved body can be created without running out of the chemical solution.

<Third Example of Construction> The improved body may be formed continuously in the axial direction as shown in FIG. 6 or discontinuously as shown in FIG. In this case, as shown in the figure, when the chemical solution is injected between the adjacent packers 6 and 6 by skipping between the adjacent packers 6 and 6, the cement bentonite or the like is previously inserted between the adjacent packers 6 and 6 to be skipped. It is desirable that the seal grout material X is injected and filled between the seal grout material X and the hole wall. This can prevent the chemical solution injected between the next adjacent packers 6 and 6 from flowing between the adjacent adjacent packers 6 and 6 through the packer 6 and the hole wall.

(Injection Principle of the Present Invention) The injection principle of the present invention which provides the above-mentioned advantages will be described again.
As shown in the figure, in the conventional double pipe double packer injection method, a cement bentonite filler S is filled beforehand with a hole wall, and the cement bentonite filler S is split by the pressure feeding of a chemical solution. Is a method of injecting a chemical solution G into the container. Therefore, the number of cleavage sites of the filler S is very small, and the chemical solution G is injected only from the cleavage site. Therefore, the permeation area to the ground is the sum of the areas facing the cleavage site, and the permeation area is extremely small.

On the other hand, in the present invention, FIG.
As shown in (1), since the chemical liquid G is injected from the entire space not filled with the filler S, the chemical liquid G is injected into the ground 30 while filling the wide space. Therefore, since the whole of the insertion hole 31 facing the space is permeated and injected with the permeation target area, a large amount of the chemical can be injected from one injection zone, and the chemical permeated into the ground can be permeated and injected far. Is done.

Actually, when the relationship between the discharge amount and the injection pressure was compared between the conventional double pipe double packer injection method and the injection method of the present invention, the results shown in Table 1 and FIG. 11 were obtained. This result also confirmed the above-described injection principle of the present invention.

[0034]

[Table 1]

[0035]

As described above, according to the present invention, it is possible to form a concentric cylindrical improved body by permeation injection, and to form a large-sized improved body having a diameter of about 5 m, for example. Is brought.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an example of an injection device.

FIG. 2 is an explanatory diagram of a first stage of the method of the present invention.

FIG. 3 is an explanatory diagram of a second stage of the method of the present invention.

FIG. 4 is an explanatory diagram of a third stage of the method of the present invention.

FIG. 5 is an explanatory view of an injection portion and a main part of an injection state.

FIG. 6 is an explanatory diagram of a stage at which the formation of the improved body is completed.

FIG. 7 is an explanatory diagram of a relationship between a packer length and a diameter of an improved body.

FIG. 8 is an explanatory diagram of a second construction example.

FIG. 9 is an explanatory diagram of a third construction example.

FIG. 10 is an explanatory diagram of the injection principle of the present invention in comparison with a conventional example.

FIG. 11 is a graph showing a comparison result between the conventional double pipe double packer injection method and the injection method of the present invention in the relationship between the discharge amount and the injection pressure.

[Description of Signs] 1 ... first pipe, 2 ... second pipe, 3 ... third pipe, 4 ... through-hole, 5 ...
Sleeve, 6 ... Packer 7 ... Filler, 8 ... Film, 10 ...
Outer pipe, 20: Injection inner pipe, 21: Inner pipe main body, 22: Discharge port, 23, 24: Packer member, 30: Target ground, 31
... insertion hole, 40 ... expansion fluid, 50 ... casing, G ...
Chemical solution, Z: improved body.

Claims (4)

[Claims] An excavator having a plurality of packers on an outer surface thereof spaced apart in an axial direction and having an inlet between adjacent packers, while excavating a target ground to a predetermined depth to form an insertion hole. A tube is relatively inserted into the insertion hole, and the two adjacent packers are bulged and brought into close contact with the wall surface of the insertion hole. At this time, an area surrounded by the adjacent packer, the wall surface of the insertion hole, and the outer surface of the injection outer tube. And filling the space from the inlet with a chemical solution at a rate of more than 10 liters / minute and not more than 40 liters / minute into sandy or gravel ground. . 2. An outer injection tube having injection ports at a plurality of axially spaced sites, and an inner injection tube movable into and inserted into the outer injection tube, wherein the inner injection tube is connected to the outer injection tube. 2. The chemical liquid injection method according to claim 1, wherein the liquid chemical is injected from different positions in the pipe by moving the liquid axially. 3. A through hole is formed in the outer tube for injection, and the packer is provided across the through hole in the axial direction. The front and rear ends of the packer in the axial direction are sealed in a liquid-tight manner with the outer tube for injection. 3. The chemical liquid injection method according to claim 2, wherein a swelling fluid is sent into the packer through the through-hole to expand the packer. 4. A through-hole is formed in the outer injection tube, a deformable sleeve is provided to cover the through-hole, and the packer is provided across the sleeve in the axial direction. Using the one whose end is liquid-tightly sealed in the outer tube for injection, the swelling fluid is fed through the through-hole, and at the time of this feeding, the sleeve is deformed to cause the swelling fluid to flow into the packer and to be packed. 3. The chemical solution injection method according to claim 2, wherein the sleeve is restored to close the through-hole in a state where the inflow is completed and the inflow is completed.