JPS6147927B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a chemical injection method for improving the ground by infiltrating a chemical into the gaps between soil particles.

Conventionally, when drilling a hole underground and injecting it for the purpose of improving the ground, it is common practice to use the boring rod used for drilling the hole as it is as an injection conduit, and to switch the drilling water to the injection material and inject it. It is true.

Since this type of boring work involves drilling the hole using the rotation of the pit at the tip of the boring rod and the pressurized water that is ejected from it, there is a risk that not only the outer periphery of the rod will be scraped off, but also the surrounding area will become loose. .

This results in the injected material leaking through gaps around the rod or through loose ground during injection, resulting in the inability to concentrate effectively on the target ground, and this happens frequently. Measures have been taken to prevent leakage, such as installing a packer in front of the point injection nozzle, but although this is effective if the rock is hard, the ground, which is generally made of sand or clay, is soft and collapsible. Since it is strong and has been disturbed by bowling, there is little hope for its effectiveness. Leakage is particularly frequent when the injection depth is shallow or when horizontal injection is performed at a tunnel face, etc., and immediate improvements are desired.

In addition, in recent years, the chemical injection method involves making the boring rod into a double pipe, guiding two types of chemical liquids that react and gel into the ground separately, and mixing the two types of chemical liquids near the tip of the injection conduit. Leakage is prevented by injection that gels in an extremely short period of time, within a few seconds, but it takes instantaneous condensation or several seconds for the injection liquid to penetrate into the gaps between fine soil particles in the ground, which is the original purpose. It is difficult to achieve a gelation time of 100 mL, and the economical penetration radius, ie, the injection range that can be performed with one injection conduit, is limited to a small area, and as a result, the customer cannot be satisfied.

The present invention satisfies the above-mentioned technical problems and provides an injection method suitable for ground improvement.

An example of the implementation of the present invention will be described below.The injection body 1 employed in implementing the present method has an appropriate number of outlet ports 2 that communicate with the internal chemical liquid channel 4 within a certain length range on the side surface of the tip end. ..., and each of these outflow ports 2 is closed by a cover 3 so as to be openable. When the injection body 1 and the cover body 3 are formed so that the diameter of the open end side surface of the injection body 1 is small, the outer diameter of the cover body 3 is the outer diameter of the injection body 1. It is formed in the shape of a cap with a cone equal to , and the section length L of each outlet 2 extending from one side to the other in the pipe direction can be freely opened and closed. (Fig. 1) Also, the cover body 3 is formed into a long tube shape without a cone, and each outlet port 2 of the cover body 3 is formed into a long tube shape without a cone.
In some cases, the injection body 1 is formed to be openable and closable, and in such a case, the tip of the injection body 1 also serves as a cone. (Fig. 3) As a result, when the injection body 1 or the cover body 3 moves by the predetermined length L, the body 3 remains in the cover body 3 in the form of a liquid volume corresponding to the volume of the cover body 3 of the length L, that is, an annular shape of the drug solution a. A circulation space b is formed, and each outlet 2 opens facing the circulation space b, and the chemical solution a sent out from each outlet 2 does not directly inject into the opposing ground A, but flows into the circulation space b. In this case, the filling state is reached and the entire space b is injected.

This outflow space b connects each outflow port 2 to the ground A.
This forms a direct inlet with directivity in all directions. The outer peripheral area of the circulation space b, which is the direct injection surface with the ground A, is configured to have a desired ratio with the area of the chemical liquid flow path 4 by increasing or decreasing the outer peripheral area of the section length in the cover 3. When the flowing chemical solution A flows into the ground A, it is significantly decelerated so that it is injected equally in all directions at a low speed. The reduction ratio is determined by the following formula.

(Inner diameter of chemical liquid flow path / 2) ² × π = X Outer diameter of circulation space × π × section length = Y Y÷X = Reduction ratio Here is a specific example of calculation (unit: mm): (20/2 ) ² × π = 314 mm ² 40 × π × 500 = 62800 mm ² 62800 ÷ 314 = 200, and the chemical injection speed to ground A is reduced to 1/200, thereby making it possible to set the injection pressure to a low pressure. be.

As the chemical solution a, a consolidating agent and other materials with various properties for soil improvement are used.

In such a pouring method, with each outlet 2 closed, the pouring body 1 together with the cover 3 is vibrated and struck by an appropriate driving machine to be driven into the target ground. In this state, if the ground A is soft and easily collapsing, the soil particles will be densely packed by the driving and will be in close contact with the surrounding sides of both the cover body 3 and the injection body 1 except for the side surfaces of each outlet 2. The gap between A and both bodies 1 and 3 is crushed and sealed. On the other hand, walls _A1 that are difficult to collapse are formed along the circumferential sides of both bodies 1 and 3. After that, the injection body 1 or the cover body 3 is moved by a section length L using a driving machine,
The chemical solution a is sent out from each outlet 2 into the circulation space b between the wall _A1 where the cover body 3 remains, and the chemical solution a is injected into the ground in all directions from the same circulation space b toward the wall _A1 . , modify the ground A.

More specifically, in the case of the injection body 1 and the cover body 3 in the configuration shown in FIG. 1, there is a retreat injection method shown in FIGS. , the injector 1 is driven deeper into the target ground A by a section length L, and then the injector 1 is
Then, the chemical solution a is sent out from each outlet 2 into the circulation space b, and the chemical solution a is injected into the ground from the circulation space b, and then again according to the depth of the ground A to be improved. The injection body 1 is repeatedly moved back for a section length L, and the injection is improved each time the injection body 1 is stopped. It is also optional to move backwards while continuing to inject. In this case, even if a part of wall A ₁ collapses, the chemical solution a in the circulation space b will become a cushion and the outflow port 2 will be clogged by being fed out. It is completely safe.
In this implementation method, the cover 3 may be separated, or appropriate measures may be taken to prevent it from slipping off when the cover 3 has moved a distance L between the injection body 1 and the cover 3 and the injection body 1 to retreat together with the injection body 1. It's also good to do. This allows the process to be divided into the first half of the predetermined implantation process and the second half of the injection process, thereby speeding up the overall construction method.

Figures 7 and 8 show the forward injection method, in which with each injection port 2 closed, the injection body 1 together with the cover 3 is driven deeply into the target ground A by a section length L that is twice as deep as the frontmost part of the target ground A, and then poured. The body 1 is moved back by a section length L, and the chemical solution a is sent out from each outlet 2 into the circulation space b of the cover body 3 that remains stationary due to the contact resistance with the ground distribution plate A, and the chemical solution a is sent from the circulation space b to the ground. Inject drug solution a into the container. After that, depending on the depth of the ground A to be improved, the injector 1 is moved forward again by a section length L, and then the cover body 3 is also moved forward by a section length L, and only the injector 1 is moved back to perform injection. Then, repeat this process to improve the injection. In this implementation method, the injection body 1 and the cover body 3
This means that an appropriate connecting means is provided so that the injection body 1 will not be separated from each other after it has moved to the section length L, and a seal is provided to prevent the chemical solution a from entering the cover body 3 in the same state. Apply. As a result, when the outflow port 2 is opened, it can be injected without interruption into the ground A facing the flow space B through the flow space B, and the wall
It is good to be able to improve the injection in a state where the soil particles are densely packed without natural collapse by minimizing the time that A ₁ is in the space, and the injection port 2 is not clogged.

Figures 9 and 10 show the forward and backward injection methods, which combine the above-mentioned backward injection method and the forward injection method. After injecting chemical solution a from space b, it is injected into _one side of the middle wall A for improvement. Also in this implementation method, a means for connecting the injection body 1 and the cover body 3 and a seal are necessary. Thereby, when the improvement of the ground A is, for example, reinforcement improvement, it is useful as an implementation method when there are soft strata before and after a relatively hard stratum.

Figures 11 and 12 show the retreat injection method according to the configuration shown in Figure 3. With each outlet 2 closed, the injection body 1 together with the cover 3 is driven deep into the target ground A, and then the section length is After moving backwards L,
Only the injection body 1 is advanced by a section length L to each outlet 2.
The chemical solution a is sent out to the circulation space b, and is injected from the circulation space to the opposite wall _A1 , and the injection body 1 is maintained in a state where it can be advanced beyond the cover body 3, and is repeatedly retreated for a section length L to improve the injection. Also, although the same type of construction is not shown in the drawings, it is possible to use the forward injection method or the previous method.
The injection may be improved by the backward injection method, and it is a matter of course that a seal is provided between the injection body 1 and the cover body 3 to prevent the chemical solution a from entering from the circulation space b.

In addition, the driving angle of the injection body 1 and the cover body 3 in each of the above-mentioned construction methods is not limited to the horizontal shape shown in the drawings.
It is carried out in relation to the construction site, such as vertically or diagonally.
Equivalent injection performance was obtained in both cases.

Therefore, according to the present invention, the soil particles are densely packed around the injection body and the covering body and come into close contact with both bodies, and the gaps between the injection body and the covering body and the ground are crushed and sealed. As a result, leakage of the drug solution that is subsequently started to be injected can be completely prevented. The annular circulation space formed in the cover trace acts as a true injection port in place of the outflow port in the injection body, giving directionality to the medicinal liquid in all directions around the injection body and guiding it equally. The chemical solution can penetrate and distribute uniformly to form a predetermined improved ground around the injection body.

Furthermore, due to the presence of the circulation space that guides the chemical liquid in this way, the area facing the ground can be made extremely large, and the injection port, that is, the outer peripheral area of the space can be made larger than the cross-sectional area of the chemical liquid flow path in the injection body. It was also possible to form a very large ratio, thereby satisfying both the desired injection volume consistent with the economical speed of construction objectives and the requirements for low pressure injection consistent with penetration theory.
Therefore, we solved the dissatisfaction with the conventional general injection method, in which the injection was injected into the ground from the tip of the injection conduit at the same speed, and that the injection amount and penetration effect were in a contradictory relationship. It has the characteristics of being able to perform construction efficiently, at an economical speed that meets the purpose, without the various adverse effects of injection pressure, and with excellent safety.

[Brief explanation of the drawing]

FIG. 1 and FIG. 3 are side views showing respective embodiments of the injection body and cover body used in the construction method of the present invention, each partially cut away. FIG. 2 is a sectional view taken along the - line. Fourth
The figure is a sectional view taken along the - line. Figures 5 and 6
7 and 8, FIGS. 9 and 10, and FIGS. 11 and 12 are partially cutaway side views showing the injection process based on different concrete implementation methods. FIG. 13 is a cross-sectional view taken along the - line. In the figure, 1 is the injection body. 2... is the outlet. 3 is the cover body. A is the ground. a is a chemical solution. b is the circulation space.

Claims (1)

[Claims] 1. Drive the injector into the ground together with the cross-sectional annular cover that closes the side outlet, move the cover or the injector until the outlet is opened, and create an annular circulation space in the remains of the cover. A chemical injection method that is characterized by sending out a chemical liquid from an outlet and injecting the chemical liquid into the ground from the same distribution space.