JPH0433926B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ground improvement type sewing method.

When constructing tunnels and underground structures, the following construction methods are used to prevent loosening of the ground and deformation of the ground surface due to excavation.

<B> Pipe roof construction method Prior to tunnel excavation, a pipe (steel pipe) is inserted along the outer circumference of the excavation cross section to form a roof that matches the tunnel shape, and as the tunnel is excavated, this roof is directly supported by shoring. , a construction method that prevents deformation of the ground surface due to excavation.

<B> Chemical injection method A method of injecting chemical solutions into the ground to reduce the permeability of the ground or increase its strength.

<C> Freezing method: Freezing pipes are driven into the ground to be frozen and solidified in advance at regular intervals, and frozen plines are circulated through the freezing pipes using a freezing machine, or gas is released into the freezing pipes from a liquid nitrogen cylinder to freeze the ground. A method of freezing and solidifying.

Each of the above construction methods has the following problems in construction.

<B> In the case of soft ground, it is insufficient to use a single construction method, so in reality, multiple construction methods are used in combination.

At this time, work for each construction method is performed independently, resulting in low work efficiency and high costs.

<B> When only a single construction method is adopted, emphasis is placed on the risk of ground collapse, which tends to lead to over-design.

The present invention was made to solve such problems, and an object of the present invention is to provide a ground improvement type sewing method that is excellent in workability, economy, and safety.

Next, an embodiment of the present invention will be described based on the drawings, but first a description will be given of the sewing material used in this construction method.

[A] Sewing material The sewing material 1 is composed of a sewing material tube 2, an inner tube 4, and a grout tube 3.

[B] Sewn pipe The sewn pipe 2 is a hollow pipe made of steel, vinyl chloride, etc., as shown in FIG.

As will be described later, the sewing pipe 2 is a long pipe whose purpose is not only to penetrate the ground and stitch it to the ground, but also to inject grout while preventing backflow.

To prevent backflow of grouting agent, for example,
As shown in the figure, a plurality of discharge holes 22 are opened in the circumferential direction on the circumferential surface of the sewing pipe 2, and a concave groove 24 concentric with the discharge holes 22 is provided. A rubber valve 25 formed by making a cut in the center of a disk made of urethane or the like is fixed by screwing or using adhesive or the like.

When pressure is applied from the discharge hole 22, this rubber valve 25 pushes the disc with the notch in the injection direction to form an open hole.On the other hand, when pressure is applied to the disc from the outside, the disc pushes the discharge hole 22. Configure to block.

As in this embodiment, each discharge hole 22 has a concave groove 24.
Since the groove 24 is recessed and the valve is installed inside the groove 24,
Sufficient strength of the sewing pipe 2 can be ensured.

[C] Internal tube The internal tube 4 has an inner diameter slightly larger than the outer diameter of the grout tube 3, which will be described later, and has the grout tube 3 inside.
to store.

That is, the tip of the inner tube 4 comes into contact with the gasket 5 that locks on the stopper 32 of the grout tube 3,
and another gasket 5 in the middle of the internal tube 4.
intervenes.

On the circumferential surface of the internal intubation tube 4 located between the seals 5,
The injection hole 41 is opened.

[B] Grout tube The grout tube 3 is slidably positioned in the inner tube 4, and is inserted into the sewing tube 2 together with the inner tube 4 so as to move forward and backward, so that it can be inserted only at a desired location inside the sewing tube 2. This is an injection tube intended for injecting one or more medicinal solutions at once.

The tip of the grout tube 3 is closed, and a stopper 32 is formed at the tip to protrude from the inner peripheral surface.

Injection holes 31 are arranged in the circumferential direction on the circumferential surface of the grout pipe 3.
In addition, on both sides of the injection hole 31, there is a gasket 5 made of a ring-shaped elastic material such as rubber.
Attach.

The purpose of the grout tube 3 and the inner tube 4 is to inject the chemical liquid etc. only from the desired discharge hole 22 when both are combined.

Therefore, when the grout tube 3 and the inner tube 4 are moved relative to each other, the packing 5 is compressed and expanded, and when the compressive force is released, it returns to its original shape.

As a result, when the packing 5 expands, the inner wall of the sewing tube 2 is pressed with considerable pressure, thereby blocking the space 43 between the grout tube 3 and the inner tube 4.

In addition, when it is desired to mix and release a plurality of chemical solutions, the inside of the grout tube 3 can be used as a passage exclusively for liquid B, for example, and a swivel or the like can be attached to the proximal end of the inner tube 4, so that the space 43 can be used as a passage exclusively for liquid A. However, when the gasket 5 expands, this space 43 is cut off midway, making it impossible to supply liquid A.

Therefore, a communication hole 34 is opened on the circumferential surface of the grout pipe 3 immediately before the space 43 is blocked, and the injection hole 3 is opened from the position of the check valve 33 provided in the grout pipe 3.
A rubber tube 6 made of an elastic material such as rubber is placed in close contact with the inner wall.

As a result, even if the packing 5 expands, the liquid A moves from the space 43 through the communication hole 34, pushes the rubber tube 6, forms an independent passage between it and the inner wall surface of the grout tube 3, and is injected. It merges with the B liquid just before the hole 31.

Therefore, since both liquids A and B can be combined and injected immediately before being injected at the injection hole 41, there is no need to worry about solidification in the pipe even if the instant setting material is used together with other chemical liquids.

Next, we will explain the construction method when used for tunnel construction.

[B] Installation of the sewn pipe A hole is bored with a known drilling device at an angle in the tunnel excavation direction, and the sewn pipe 2 is installed in this hole.

The following two methods can be considered for arranging the sewing pipe 2 underground.

One method is to use the sewn pipe 2 as an outer casing, perform drilling together with an inner rod having an inner bit at the tip, and then pull out the inner rod from inside the sewn pipe 2, leaving the sewn pipe 2 underground. It is.

Another method is to make a hole in the existing outer casing and inner rod, remove the inner rod from the outer casing, replace the sewing pipe 2, and then remove the outer casing from underground.

Note that it is also possible to form the sewn pipe 2 by combining a steel pipe and a vinyl chloride pipe.

In this case, if the seam pipe 2 made of vinyl chloride pipe is arranged within the cross section of the tunnel, the ends of the seam pipe 2 can be easily destroyed during excavation.

[B] Chemical injection (low-pressure grouting) Once the tip of the sewing pipe 2 is closed and placed in the ground using a known method, a packer is placed on the proximal end of the sewing pipe 2, and a grout is placed inside the sewing pipe 2. A grouting tube 3 equipped with an internal tube 4 is inserted.

Next, the grout tube 3 and the inner tube 4 that accommodates the grout tube 3 are mutually moved within the sewing tube 2 to inflate the packing 5, and then the grout tube 3 and the inner tube 4 are moved.
When a known grouting agent is filled at low pressure from the base end of each hole, the grouting agent is filled into the drilled hole from the discharge hole 22 while preventing backflow.

Since the rubber valve 25 is attached, there is no worry that the grout once spouted will flow back into the pipe.

The reason why the grouting agent is filled at low pressure is to form a uniform grout layer between the sewn fabric pipe 2 and the ground to achieve appropriate adhesion and to prevent unnecessary filling of the grouting agent.

[C] Partial filling (high-pressure grouting) If there are groundwater aquifers, cracks, etc. in the part of the ground that the seamed pipe 2 penetrates, it is necessary to improve the ground at these locations.

Therefore, when drilling, it is necessary to judge the geology from the soil removed and understand the location of cracks and underground water layers.
Based on this information, we concentrate on these areas and fill them with chemicals to improve the ground.

To fill these areas with chemical solution, it is pumped under high pressure, breaks through the grout layer filled at low pressure, and actively penetrates into crack occurrence areas and underground water layers.

At this time, since the grouting agent is filled over the entire area between the ground and the sewn fabric pipe 2, the chemical solution does not unnecessarily permeate over a wide area.

Therefore, the chemical solution is concentrated and discharged only at a location close to the group of injection holes 41 at a certain specific position.

As a result, the chemical liquid enters the crack occurrence area and the underground water layer, making it possible to improve the ground in stages (partially).

[d] Excavation After completing the specified grout injection, the grout pipe 3 and the inner tube 4 are removed, and after filling the seam pipe 2 with mortar etc., excavate in the tunnel excavation direction with the seam pipe 2 buried. do.

The proximal end side of the seamed pipe 2 located within the excavation cross section is sequentially cut as the excavation progresses, but the rest remains underground as is.

As a result, the ground around the tunnel is sewn together through each layer by the sewing pipe 2, and at the same time, if there is an underground water layer or crack, the ground can be appropriately improved and a stable state can be maintained. .

[E] Other Embodiments It is also possible to consider adopting a slit rubber valve 26 in which a slit 27 in the circumferential direction is formed on the surface of a disk made of rubber, urethane, etc., which is installed on the bottom surface of the groove 24, as shown in FIG. It will be done.

The slit 27 is opened at a position that avoids the discharge hole 22 and forms a passage between the disk and the bottom of the groove 24 during grouting, but even if external pressure acts on the slit 27, the bottom of the groove 24 will not open the passage. Form in a position where it can be blocked.

It is also conceivable to adopt a check valve formed by enclosing a rubber ring (not shown) made of a ring-shaped elastic material and capable of covering the discharge hole 22 on the circumferential surface of the sewing pipe 2.

Since the present invention is as explained above, the following effects can be expected.

<B> Conventionally, multiple construction methods were used in combination when soft ground existed, but the present invention uses a sewn ground pipe as a grout injection pipe, and is expected to have both a lock bolt effect and a ground improvement effect. can do.

Therefore, it is possible to significantly improve work efficiency and reduce costs.

<B> It is possible to inject chemicals in stages according to the strata.

Therefore, it is possible to prevent the injection of expensive chemicals in excess of the required amount, which is not only economical but also provides a good ground improvement effect.

<C> Since more than one chemical solution can be ejected at the same time, it becomes possible to use a supersetting agent, which was previously considered difficult to use together.

<D> Since the discharge hole has a backflow prevention function, it is possible to prevent the inflow of earth and sand when the tube is inserted, and it is also possible to effectively prevent the backflow of the chemical solution when the chemical solution is injected.

[Brief explanation of drawings]

Figure 1: An explanatory diagram of one embodiment of the sewing material, Figure 2:
Cross-sectional view of the sewing material, Figures 3 and 4: Explanatory diagram of the construction method, Figure 5: Cross-sectional view of - in Figure 4, Figure 6: Cross-sectional view of - in Figure 4, Figure 7:
A sectional view of the vicinity of the discharge hole of the sewing pipe, FIG. 8: An explanatory diagram of another embodiment. 1... Sewing material, 2... Sewing pipe, 3... Grout pipe, 4... Internal intubation tube, 5... Packing, 25... Rubber valve.

Claims (1)

[Claims] 1. Using a seamed pipe in which a plurality of discharge holes with a backflow prevention function are provided along the longitudinal direction of the pipe body on the circumferential surface of the pipe body, a plurality of the seamed pipes are installed in the ground to be excavated. This is a soil improvement type seaming construction method in which the material is penetrated at an angle in the direction of the main cross section, and the chemical liquid is ejected from the discharge holes at arbitrary positions in the seamed pipe to prevent backflow and solidify the surrounding ground.