JPH02217515A - Tip device of double-wall injecting pipe - Google Patents

Abstract

PURPOSE:To simplify the composition of a tip device, and lower the cost of the device, and prevent the reverse current of excavation water or chemical solution certainly from being generated by fitting flexible internal pipes made of cylindrical flexible material, at the tip sections of steel internal-pipes. CONSTITUTION:At the tip ends of the external pipes 3 of double inject pipes 1 consisting of steel internal-pipes 2 and the external pipes 3, metal crowns 4 are connected via connecting pipes 5, and at the tips of the internal pipes 2, flexible internal pipes 7 made of flexible material are fitted so that the tips of the pipes 7 may be positioned near the tip sections of the metal crowns 4. When excavation is executed by using the tip devices, then pressure-feeding water pressure is received on the outer peripheries and the internal pipes 7 shrink to come in close contact with the devices, and the reverse current of excavation water or injecting chemical solution is prevented from being generated into the internal pipes 2.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to an injection pipe tip device used in a chemical injection method for the purpose of water stopping and strengthening soft ground.

In particular, the present invention relates to an advanced device that uses a double pipe used in a hole in the ground as a chemical injection pipe.

``Prior art and problems to be solved by the invention'' Usually, the method most commonly used in the injection method using double pipes is the outer pipe of double steel pipes consisting of an inner pipe and an outer pipe. A metal crown (full-hole bit) is attached to the tip, the chamber is drilled to a predetermined injection depth, and the double tube used for the chamber hole is used as an injection tube to inject the chemical solution.

That is, as shown in FIG. 4, a typical conventional example is composed of an outer tube 3 of a steel double tube consisting of an inner tube 2 and an outer tube 3, a metal crown 5, and a connecting tube 4. A mixing chamber 6 is formed below the inner tube 2, which is shorter than the outer tube 3.

When a drug solution is injected using a conventional device having a double-tube tip mechanism as described above, there are the following drawbacks.

a) The chemical solutions used to drain water from springs at excavation sites, etc. are instant-setting with an extremely short gel time. When they merge at the tip (two-shot method), gel is partially generated in the injection tube (the mixing chamber 6) because it is instantaneous, and the generated gel is destroyed and released (injected) from the tip of the injection tube, so it cannot be stopped. The disadvantage is that the water effect is inferior.

In order to solve this drawback, the tips of the inner tube and the outer tube must be in the same position, that is, the metal crown of the outer tube and the inner tube must have the same length.

However, if the tip of the inner tube is made of steel, it is impossible to excavate the ground, and it is technically difficult to attach a metal crown to the tip of the inner tube separately from the outer tube. However, the strength of the inner tube itself is insufficient, making it virtually impossible.

b) When making a hole using a conventional double pipe in places where the target ground is dense sandy soil and the water pressure is high, water is usually passed through an outer pipe with a large cross-sectional area. ) When the flow of water is interrupted, such as by adding a pipe, pressurized water may flow back into the inner pipe with sediment, burying the inner pipe.

Further, even if polling water is passed through both the inner and outer pipes, a similar phenomenon occurs, and the inner pipes are filled with earth and sand.

C) In a double-pipe composite injection method in which a chemical solution with an instant gel time (usually 10 to 20 seconds or less) and a drug solution with a slow gel time (more than 1 minute) are injected at the same injection position (injection stage),
While constantly injecting a slow-setting drug into the outer tube (stopping injection from the inner tube at this time), add the quick-setting agent from the inner tube.
In the case of the pressurized injection method that uses instant-setting chemical liquid, the instant-setting chemical liquid is injected to fill the voids around the injection pipe and the rough gaps in the ground, and then the slow-setting chemical liquid is injected under pressure. The slow-setting chemical solution from the tube flows back into the inner tube, reacts with the quick-setting agent in the inner tube to form a gel, and blocks the inside of the tube.

Therefore, subsequent injection of instant-setting drug becomes impossible.

In order to solve the problems b) and c) above, conventionally, a check valve made of steel is attached to the tip of the inner pipe.

However, conventional backflow valves generally have a complicated mechanism, are prone to failure, tend to become inoperable due to solidification of the chemical solution, and have drawbacks such as high costs due to the labor required for processing.

"Means for Solving the Problems" This invention solves the problems of the injection method, in which the double pipe is used as an injection pipe after making a hole in the ground, and especially the injection pipe tip device used therein. As a result of intensive research,
By installing a tip device made of flexible material at the tip of the steel inner tube, it is possible to reliably prevent backflow without interfering with the pores, and the injection mechanism is simple and can be installed at low cost. This paper proposes a tube tip device.

"Example" Embodiments of the present invention shown in the drawings will be described below.

(First invention) The injection pipe l is a double pipe consisting of an inner pipe 2 and an outer pipe 3 made of steel, and a metal crown (hole bit) 5 is connected to the tip of the outer pipe 3 via a connecting pipe 4. Connected to this metal crown 4
A flexible inner tube 7 made of a flexible material is attached to the tip of the steel inner tube 2 located above the tip.

As shown in FIG. 1, this flexible inner tube 7 forms a cylindrical cavity 8 inside thereof that communicates with the inner tube 2 when no external pressure is applied, and the tip thereof is made of metal. The length is set so that it is located near the tip 9 of the crown 4.

In this case, it is preferable that the tip of the flexible inner tube 7 and the tip 9 of the metal crown 4 are in the same position, but they do not need to be in the exact same position, and even if the positions are slightly different up and down, Problem (Unlike steel, it is a flexible material, so it can stretch and bend, and depending on the soil type, it can have holes)
If not, there is no problem.

Examples of flexible materials constituting the flexible inner tube 7 include flexible rubber, polymeric resin (soft synthetic resin), cloth, and other soft materials with appropriate strength and durability. It can be used without limitation.

Using the injection pipe 1 with the tip device configured in this manner, injection work was carried out using an instant-setting chemical solution with a very short gel time for the purpose of stopping spring water from a defective lap spot on a sheet pile at an excavation site. In this case, for example, even if water glass is pumped into the outer tube 1 as liquid A and calcium chloride solution is pumped into the inner tube 2 as liquid B at the same time, both liquids A and B of the double tube tip device will not come into contact with each other. Only after they are released into the ground, they are mixed together and gelled in an extremely short gel time.

For this reason, as in the past, a gel is generated locally in the mixing chamber 6 at the tip of the double tube, and the resulting gel is destroyed and released (injected) from the tip of the injection tube, resulting in waste of chemical liquid. (As a result, the water-stopping effect can be greatly enhanced.

Of course, the advanced device of the present invention can be used for general ground injection, including the above-mentioned spring locations.

In addition, the advanced device of this invention can be used to instantly connect double pipes,
Needless to say, it can also be used in composite injection methods.

Since the flexible inner tube 7 is flexible,
Normally, as shown in Figure 1, a hollow part 8 is formed to form a cylindrical shape, but if external pressure is applied to the outer circumference, the pressure will compress and contract as shown in Figure 4a. The inner surfaces of the tubes come into close contact with each other, and function as a check valve to close the tip of the inner tube 2.

That is, when using such a double-pipe tip device to force excavation water from the outer tube 1 to the injection position, the flexible inner tube 7 receives the pressure of the pumped water on its outer periphery and contracts. In order to fit tightly, the tip of the inner tube 2 is closed, and the inner tube 2 can be smoothly drilled on any ground without being clogged with earth and sand.

In addition, when using conventional double pipes to make a chamber hole (usually using an outer pipe with a large cross-sectional area) in a place where the ground to be poured is sandy and the pressure water is high, it is necessary to add a lot of double pipes, etc. When the water supply is interrupted, pressurized water may flow back into the inner pipe 2 along with earth and sand and fill the inner pipe 2, making subsequent injection using the inner pipe 2 impossible. In such a case, according to the advanced device of the present invention, the flexible inner pipe 7 functions as a check valve and contracts and closes against the pressurized water, completely preventing backflow to the inner pipe 2. can do.

On the other hand, when performing compound injection using a conventional double tube, while constantly injecting a slow-setting drug solution into the outer tube 3 (injection from the inner tube 2 is stopped at this time), it is rapidly injected into the outer tube 3. In the case of the pressurized injection method, in which the binders are combined to form an instant-setting chemical solution, the instant-setting chemical solution is injected to fill the voids around the injection pipe or rough gaps in the ground, and then the slow-setting chemical solution is injected under pressure. However, at this point, the outer tube 3
The slow-setting chemical solution flows back into the inner tube, undergoes a gelling reaction with the quick-setting agent in the inner tube 2, and blocks the inside of the tube.

For this reason, there is a drawback that subsequent injection of the instant-setting drug solution becomes impossible.

On the other hand, if the double tube tip device of the present invention is used, as shown in FIG. However, since the tip of the inner tube 2 is closed by the contraction of the flexible inner tube 7 due to this pressure, there is no possibility that the loosely binding liquid will flow back into the inner tube 2 (therefore, the loosely binding liquid will not flow back into the inner tube 2). It undergoes a gelling reaction with the quick-setting agent inside the tube, and does not block the inside of the tube.

Next, if the quick-setting agent is fed under pressure from the inner pipe 2, the inner pipes 2, whose inner sides are in close contact with each other, will easily open under pressure, and the quick-setting agent will be released into the ground, and the outside will be released. It merges with the slow-setting chemical liquid discharged from the pipe 3 and becomes an instant-setting chemical liquid, which is injected into the ground.Furthermore, if the pressure feeding from the inner pipe 2 is stopped in this state, the inner pipe The inside of 2 is automatically tightly closed.

As described above, the present invention is easy to process because it is made of a flexible material, and unlike check valves made of steel, it is inexpensive, simple, and functions as an excellent check valve with fewer failures.

Therefore, this type of composite injection becomes very easy and the workability is improved.

(Second Invention) A second invention shown in FIG. 2 is such that, in the configuration of the first invention, an elastic restoring force is maintained in the closing direction at least in the vicinity of the tip of the flexible inner tube 7, and the medicinal solution is kept in the inner tube 2. In a state where no pressure is applied to the inside of the flexible inner tube 7 due to pressure feeding, even in a natural state where no external pressure is applied, the flexible inner tube 7 is configured to be tightly closed by elastic restoring force.

As a means to exert such elastic restoring force,
For example, as shown in FIG. 3, a pinching elastic member IO, such as a sandwiched leaf spring made by a pair of spring steel plates pivoted to each other at both ends, is attached to the periphery of the tip of the flexible inner tube 7. A structure in which the opening at the tip of the flexible inner tube 7 is closed by pressing, or a structure in which the flexible inner tube 7 is molded from an elastic material such as rubber, and the tip is closed by shrinking at the time of molding. It is possible to use a structure in which the tip opening is opened by processing the tip so that when the chemical solution is pumped therein, the internal pressure overcomes the elastic restoring force.

By creating a structure in which the tip opening of the flexible inner tube 7 is tightly closed with elastic restoring force in its natural state, it can be reliably closed even when external pressure such as drilling water or chemical liquid from the outer tube 3 is not applied. By closing the opening at the tip, the function as a check valve can be made more reliable, and when the medicinal solution is force-fed into the inner tube 2, the compressive elasticity of the flexible inner tube 7 is reduced by the pressure. The member 10 can be pushed open to open the distal end opening and the medical solution can be discharged. In this state, when the pressure feeding of the medical solution from the inner tube 2 is stopped, the elastic restoring force immediately closes it automatically. If external pressure is applied by the chemical liquid from the pipe 3, a more reliable seal can be achieved, and excess leakage of the chemical liquid from the inner pipe 2 and backflow of the chemical liquid and drilling mud from the outer pipe 3 can be completely prevented.

Therefore, the tip device of the second invention differs from the first invention only in that the tip opening of the flexible inner tube 7 is forcibly closed tightly by elastic restoring force to ensure closure. Other basic functions, configurations, uses, etc. are the same as those of the first invention.

Note that the flexible inner tube 7 having a tip opening automatic closing function used in the second invention is a tip device that mixes and injects liquid medicine from the inner and outer tubes in a mixing chamber provided in the tip of the injection tube 1. If it is attached to the inner tube of the tube and its tip is positioned within the mixing chamber, it can also be used as a check valve to prevent backflow into the inner tube.

As another example of application, the distal end of the flexible inner tube 7 may be completely closed and a plurality of injection holes may be provided on the side surface thereof.

When injection is performed using this tip device, liquid A is discharged from the outer tube 3 in a vertical direction, while liquid B flows into the injection hole on the side of the inner tube 2 in a direction perpendicular to liquid A. Mixing of both liquids A and B can be improved.

However, this advanced device cannot be used for chemical solutions that react instantaneously when liquids A and B are mixed together, such as a combination of water glass and calcium chloride solution.

As described above, in this invention, even if the flexible inner tube 7 made of a flexible material is attached to the steel tip of the double tube, it is possible to make all the holes smoothly as in the conventional double tube. It is also an excellent injection tube tip device that can eliminate various problems of conventional double tubes even if the double tube is used as an injection tube as is.

Further, the present invention will be described in detail by giving examples.

Example 1 At an excavation site, spring water was injected using the advanced device of the first invention for the purpose of gushing out spring water from a defective lap spot in a sheet pile.

The soil at the spring location (near GL-6,0m) was a sandy layer, and the spring water flow was approximately 20β/min.

At a point approximately 1 m away from this spring water point (the sheet pile installation position), water was passed from the outer pipe and a GL-6.0m narrow hole was created without any problems.

Next, a JISB water glass aqueous solution (specific gravity 1.3) is pumped into the outer tube as liquid A, and at the same time, a calcium chloride solution (specific gravity 1.3) is pumped into the inner tube as liquid B. 0 seconds) were injected at 20 I2 per minute.

At the initial stage of injection, a small amount of diluted soft gel was mixed into the spring water, but there was no hard gel that was not diluted into the water, and approximately 1.
When I injected 502, the water stopped.

Comparative Example 1 Under the same conditions as in Example 1, water was injected into a spring location (spring water volume: 17β) using a conventional double pipe tip device (FIG. 5).

As a result, a large amount of hard gel that cannot be diluted with water (gel formed in the mixing chamber at the tip of the double tube) was mixed in with the soft gel that was diluted with spring water at the same time as the injection.
I was able to stop the water by injecting beta.

Example 2 Composite injection was performed using the advanced device of the second invention in a mountain sand layer under Chiba Prefecture (a dense, fine sandy ground with an N value of 40 to 50, and there is not much groundwater).6 First, GL Water was passed through the outer tube up to -6.0 m, but the holes were able to be formed without any problems.

Next, add liquid A (per 1 m3 of JIS No. 3 water glass 350 I2, glyoxal (concentration 40%) 160
β, a slow-setting chemical solution with a gel time of 12 minutes by mixing 490% water and at the same time, pumping solution B (phosphoric acid per 1 m) into the inner tube.
Concentration 98%) 90β, water 910I2 (quick setting agent) was pumped, A liquid: B liquid was mixed in a ratio of 3 = 1, and 4012 injections of instant setting chemical solution with a gel time of 4 seconds were injected (discharge amount of A liquid). 9β/
minutes, B solution 3. e/min), the injection pressure was 8 kgf/
It was m2.

During injection, no spurt of drug solution was observed along the injection tube. After that, stop injecting liquid B and inject only liquid A.
When I2 was injected, the injection pressure was 5 kgf/m'', which allowed for smooth injection, and no spouting of the chemical solution onto the ground surface was observed.

Furthermore, the injection tube was pulled up 50 cm and both A and B were injected at the same time, but the injection pressure was the same as before, 8 kgf/m'', and A.
The liquid alone was 5 kgf/m''.

Thereafter, the above-mentioned injection was carried out in three steps, and the work was completed without any problems.

After injection, the injection tube (double tube) was pulled up and the tip of the inner tube was examined, but no intrusion of the drug solution into the inner tube was observed.

Later, when the site was excavated and investigated, it was found that the area around the injection pipe and the rough ground was filled with a homogel-like instant-setting chemical, and the loose-setting chemical had penetrated and solidified around it.

Comparative Example 2 Injection was carried out under the same conditions as in Example 2, except that the tip device was the conventional device shown in FIG.

Holes were formed up to a predetermined depth without any problems.

First, when both liquids A and B were injected at the same time, the injection pressure was 8 k.
After that, when only liquid A was injected, it was 5 kgf/m'', and there was no ejection of the chemical solution (Example 1).
It was the same.

Next, when the injection tube was pulled up 50 cm and liquids A and B were injected at the same time, the injection pressure increased to over 30 kgf/m'' and injection became impossible.

When we pulled up the injection tube and examined the tip, we found that the inner tube was clogged with liquid medicine.

After removing the chemical solution inside this tube, we reinstalled the injection tube at a predetermined depth, and the first injection (fast-setting and slow-setting injections) was as smooth as above, but then we pulled it up and started the second injection. When I tried to do this, the pressure rose as before and I was unable to inject, so when I pulled up the injection tube and examined it, I found that the inner tube was clogged with chemical solution.

Furthermore, similar operations were performed, but the results were the same.

As described above, in the conventional double tube tip device, when liquids A and B are injected at the same time and the injection of liquid B is stopped, liquid A flows back into the inner tube, and liquid B remaining in the inner tube ( This is because it reacted with the gelling agent (accelerating agent) and turned into a gel.

In contrast, this invention has an excellent double-pipe tip that can be sufficiently effective as a check valve simply by attaching a simple flexible inner pipe made of a flexible material to the tip of a steel inner pipe. It turns out that it is a device.

``Effects of the Invention'' As described above, according to the present invention, in the injection tube for drilling and injection, which has a metal crown attached to the tip of the outer tube of a double tube consisting of an inner tube and an outer tube made of steel, the metal crown A cylindrical flexible inner tube made of a flexible material is attached to the tip of the inner tube located above the tip so that the tip is located near the tip of the metal crown.
It is possible to construct an extremely low-cost cutting-edge device that is mechanically extremely simple and does not interfere with excavation when the hole is open, and is free from breakdowns and malfunctions.It also reliably prevents the backflow of chemical liquid and excavation water from the outer pipe. This enables stable construction without clogging the inner pipes due to chemical solutions or backflowing muddy water.

Furthermore, when the distal opening of the flexible inner tube is configured to be closed by elastic restoring force as in the second invention, the distal opening is automatically and reliably closed regardless of the presence or absence of external pressure. The function as a check valve can be further improved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional front view showing the inner tube open state in the tip device of the first invention, FIG. 2 is a longitudinal sectional front view showing the inner tube closed state in the tip device of the second invention, and FIG. A cross-sectional view of the tip of the flexible inner tube, FIGS. 4a and 4b are longitudinal sectional front views showing a state in which injection work is performed using the tip device of the present invention, and FIG. 5 is a longitudinal sectional view of the conventional tip device. It is a front view. ■...Injection tube, 2...Inner tube, 3...Outer tube, 4...Metal crown, 5...Connecting tube, 7...Flexible inner tube, 8...Cavity part, 9...Metal crown Tip part, 10...Pinching elastic member. Figure 4 (a) (b) Figure 1 Figure 2 Figure 3 Figure 5

Claims (1)

[Scope of Claims] 1) In an injection tube for drilling and injection, which has a metal crown attached to the tip of the outer tube of a double tube consisting of an inner tube and an outer tube made of steel, the hole is placed above the tip of the metal crown. A double tube characterized in that a cylindrical flexible inner tube made of a flexible material is attached to the distal end of the inner tube so that the distal end thereof is located near the distal end of the metal crown. The injection tube tip device used. 2) Claim 1 characterized in that the flexible inner tube maintains an elastic restoring force in the closing direction at least near its tip so as to close the tip opening when no pressure is applied inside the flexible inner tube. An injection tube tip device using the described double tube.