JPH02217514A - Chemical solution injecting construction - Google Patents

Abstract

PURPOSE:To improve the uniform infiltration of chemical solution and injecting density, and improve water stopping property and ground strength by injecting compressed gas into ground, and by removing compressed air quickly, to form a non-aqueous pressure-reducing space and to inject the chemical solution into the space. CONSTITUTION:Through a single or plural sections of ground, pits are bored, and a double pipe rod 6 is set, and by using its internal pipe 7, compressed air is fed into the ground from a compressor 1 via a valve 2, and a dry area 10 is formed. After that, the valve 2 is closed, and a valve 3 is released, and air is removed, and an automatic valve 9 to be opened with fixed or lower pressure by reducing pressure in the dry area 10 quickly is released, and injecting chemical solution is fed into the dry area 10 and infiltrated into the ground. Then, in the ground, a strong cut-off wall is constructed, and injecting areas are lapped and work is continuously executed. Besides, by injecting construction, the injection areas are enlarged and, at the same time, the work may be repeatedly executed.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a chemical injection method.

More specifically, the present invention relates to a new chemical injection method that enables uniform injection and increased injection density to improve water-stopping properties and ground strength.

(Previous technology and its issues) Conventionally, chemical solutions have been injected into ground boreholes for the purpose of increasing ground strength through ground improvement, stopping water in permeable ground, anchoring rock bolts and ground anchors in spring ground, etc. The injection method is known.

Various types of these injection methods are known, such as rod injection method, strainer injection method, double pipe injection method, and high-pressure injection injection method. Also known are cement-based suspension type and water glass or polymer-based solution type.

Although these methods are effective for improving the ground affected by soft rock or groundwater, the reality is that there are many problems that need to be improved in actual construction.

In other words, in the construction methods up to now, studies have been mainly made to improve the pharmaceuticals used.

For example, when using suspension-type injection materials such as cement-based and cement/water glass-based injection materials, although they have excellent strength and durability, they have inferior permeability compared to solution-based injection materials, generally have a long gel time, and are prone to washout. It has the disadvantage of being easily diluted. Therefore, in order to improve permeability, colloidal cement (1
5 μm, 30% or less) and ultrafine cement (10 μm,
10% or less) have been developed, and Ceracola-based pharmaceuticals have also been put into practical use as accelerators to shorten gel time.

On the other hand, in the case of solution type, there are problems with strength and durability.
It is also costly. For this reason, regarding the solution type,
It has also been proposed to react with a high concentration water glass seed organic hardener as a solution-type injection material for high strength.

However, despite these improvements, there are limits to the improvement of geological strength and water-stopping properties through chemical injection in the existing construction methods, and the construction methods do not adequately address the heterogeneity of the ground. However, the disadvantage is that the chemical solution injected into the ground cannot be accurately controlled.

These drawbacks cannot be overcome by improving the pharmaceutical science, and it is necessary to improve the injection method itself. Furthermore, regarding this point, a so-called induction injection method using an air flow has been studied, and jet kraut method and CCP method using a high-pressure jet method have also been proposed, but their usage is limited.

This invention was made in view of the above circumstances,
To provide a new chemical injection method capable of eliminating the drawbacks of conventional chemical injection methods and improving uniform penetration of the injected chemical into the ground and injection density in order to improve water stoppage performance and increase ground strength. It is an object.

(Means for Solving the Problems) This invention solves the above problems by drilling a hole in the ground, injecting compressed gas into the ground, and then rapidly venting the compressed gas to create a non-aqueous depressurized space. Provided is a chemical liquid injection construction method characterized by forming a chemical liquid and injecting a chemical liquid into the space to allow the chemical liquid to permeate into the ground.

In addition, the present invention provides, as a preferred embodiment, repeating the steps of injecting and deaerating the compressed gas and injecting the drug solution within a time period during which the injected drug solution does not solidify, and performing these steps in a plurality of holes. It is something to do.

The construction method of this invention will be explained in order: <a> First, a hole is drilled in a predetermined ground. In this case, drilling can be performed in a single location or in multiple locations depending on the size of the decompressed space to be formed and the characteristics of the ground.
An injection rod such as a double pipe or triple pipe is installed in this perforation. The depth of this rod can be, for example, 50 m or more.

<b> Inject compressed gas, such as air, or other high-pressure gas such as CO2 scum or N2 gas, using the system within the installed injection rod pipe. In this case, it is preferable to prevent the injected gas from leaking through the gap between the drilling ground and the installation rod by using a backing provided around the rod.

The compressed gas injected in this way eliminates the groundwater in the ground and creates a space filled with gas higher than the initial ground water pressure. The minute obstructions that are present in the space and which obstruct the passage of the injected drug solution also move toward the outer periphery of this space.

<C> Next, the compressed high-pressure gas is rapidly vented using the same system or a different system of injection rods.

At this time, due to the difference in the moving speed of the liquid (water) and gas in the ground, the gas is discharged first, so the ground remains dry for a certain period of time until the water returns when the gas is discharged. A non-aqueous reduced pressure space (pseudo-vacuum space) is formed in a state where the pressure is lower than the initial pressure.

<d> In the present invention, an appropriate drug solution such as a suspension type or a solution type can be used as the drug solution to be injected into this space using a single system or a plurality of injection rods.

The chemical solution can be injected at low pressure without encountering resistance from groundwater or micro obstacles.

Therefore, there is no vein-like seepage into weak parts of the ground that tends to occur with high-pressure injection into the target injection area, and highly uniform injection and seepage is possible despite the unevenness of the ground.

In the above process, even when using a suspension-type injection material such as cement, which has excellent strength and durability but poor permeability, this process can be repeated multiple times within the time that the injection chemical solution does not solidify. By repeating the injection, it is possible to improve the injection effect.

In this case, the next compressed gas is injected while the injected layer that has already injected and penetrated has not solidified, and the gas is evacuated to remove this injected layer to the outer periphery of the dry space, and the next injected layer is placed inside it. will be formed. As a result, the penetration by the injection of the chemical solution is made uniform, and its density is also greatly improved.

Next, this invention will be explained in detail.

(Example) First, looking at the effects of this invention method, there is a difference in the amount of injection per hour between when the chemical solution is injected under normal pressure and when the chemical solution is injected under reduced pressure with almost no pressure. obtained the following result: reduced pressure injection (Wl)/normal pressure injection (w2) = 2.5 to 1.5 (2.1 times on average).

As described above, it can be seen that the injection effect according to the present invention is extremely excellent in efficiency.

The attached drawings illustrate one embodiment of the invention. FIG. 1 is a sectional view schematically showing the construction method of the present invention.

In this example, a hole is drilled in the predetermined ground, a double pipe rod (6) is installed, and the inner pipe (7) is connected to the compressor (1).
).

Pass the valve (2) from the compressor (1) through the inner pipe (
7) Send compressed air into the ground. A dry area (10) is formed by this compressed air. The pressure of the compressed air at this time can be set within an appropriate range similar to the conventional method, and the depth of the rod (6) can be set to a deep depth of 50 m or more. Note that by effectively using the packing (8), the rod (6) can be made shallower.

The seal (8) prevents compressed air from leaking into the dry area (10).

The size of this dry area is usually 0 as an initial state.
．． The length is approximately 8 to 1.5 m, but it can be set appropriately depending on the physical properties of the ground.

For example, 50 m by air at the pressure of hydrostatic glass alpha (alpha is determined by the physical properties of the ground).
A dry area (10) is formed at such a deep depth.

Once this dry area (10) is formed, the valve (2)
) and open valve (3) to vent air. At this time, the pressure within the dry area (10) is rapidly reduced. Open the automatic valve (9) that opens below a certain pressure, and inject the drug solution (11).
) into the dry area (10〉).

When the groundwater removed by the compressed air returns to this dry area (10) and the pressure returns, the automatic valve (9)
is closed to prevent backflow of the injected drug solution (11).

The valve (3) is designed to close when the air is removed, but if an automatic valve is provided at the tip of the inner pipe (7), the automatic valve (9) will be closed.
), it is possible to prevent backflow of the injected chemical solution (11) and groundwater.

FIG. 2 is an example of the repeated injection method of the present invention.

Explaining the process in order: (1) A hole is drilled in the ground, compressed gas is introduced into the injection rod (22), and a pressurized dry area (23) is formed at the tip of the injection rod (22).

■ The air is then rapidly vented to create a depressurized space (pseudo-vacuum space)
(24) is formed in the ground.

(2) A predetermined drug, for example, a cement-based suspension, is sent to the injection rod (22) to form a primary injection area (25) in the non-aqueous vacuum space (24).

(2) Compressed gas is then again injected from the injection rod (22) to form a pressurized dry area (26).

■ Vent the air again to create a secondary non-aqueous decompression space (27), and ■ Inject the chemical solution again to form a secondary injection area (28).

This repeated injection can promote expansion of the chemical solution injection area, uniform penetration of the chemical solution, and improvement in density.

Of course, these processes require solenoid valves, pressure sensors,
Moisture sensors, flow rate meters, current meters, etc. can be appropriately placed and computer control can be used to quickly respond, making it even more effective when the construction is on a larger scale or requires precision construction.

Figure 3 shows three implants 2 to form the same implant area.
An example is shown in which a heavy pipe rod (100) is used.

These rods (100) may be constructed at the same time through the same operation, or may be constructed in different steps depending on the characteristics of the ground, and there are many other possibilities. Not even.

(Effects of the Invention) According to the present invention, as explained in detail above, a strong water-stop wall can be constructed in the ground, and the purpose can be achieved continuously while wrapping the injection area.

In addition, since a uniform injection ground is formed, water-stopping performance is good.

It is also effective for cement-based suspension type injection, which has poor permeability, so the use of this cement-based injection material allows ground improvement with excellent strength and stability at low cost.

Since the construction method of this invention can be applied to any direction of the ground, - For example, if used horizontally, it will be useful for stabilizing the face of a spring water tunnel.For example, it can be used as a rock bolt as an injection rod, or as a ground anchor. If hollow bolts are used, the constant-starting method works effectively even on ground where the influence of groundwater is large and stability cannot be ensured with conventional methods.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of the construction method of the present invention. FIGS. 2 and 3 are cross-sectional views showing other examples. 1... Compressor 2, 3.4... Pulp 5... Injection chemical pump 6... Double pipe rod 7... Inner pipe 8... Packing 9... Automatic valve 10... Dry area 11... Injected chemical solution 21... Ground 22... Injection rod 23... Pressurized dry area 24... Non-aqueous decompression space 25... Primary injection area 26 ... Pressurized dry area 27 ... Secondary non-aqueous decompression space 28 ... Secondary injection area 100 ... Double injection pipe rod

Claims (5)

[Claims] (1) After drilling a hole in the ground and injecting compressed gas into the ground,
A chemical injection method characterized by rapidly releasing compressed gas to form a depressurized space, and injecting a chemical into the space to permeate into the ground. (2) A chemical liquid injection method characterized in that the steps of injecting and venting compressed gas and injecting the chemical liquid according to claim (1) are repeated during a time period during which the injected chemical liquid is not fixed. (3) The chemical liquid injection method according to claim (1) or (2), wherein the chemical liquid is injected without applying high pressure. (4) The chemical liquid injection method according to claim (1) or (2), which uses multiple pipes for injecting and deaerating compressed gas and for injecting the chemical liquid. (5) The chemical liquid injection method according to claim (1) or (2), wherein the injection and degassing of compressed gas and the chemical liquid injection are performed in a plurality of perforations.