JP3273178B2 - Construction method of underground stress relief groove - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for constructing an underground stress relief groove.

[0002]

2. Description of the Related Art There is a case where an external force or vibration is applied to an underground structure from the outside. The case where an external force is applied to the underground structure is, for example, a case of a freezing method in which the ground around the starting shaft of the shield machine is frozen to prevent the inflow of earth and sand at the time of starting. If the ground freezes, the ground around the shaft will expand due to the increase in water volume, and the pressure will adversely affect the structure.

[0003]

Conventionally, in such a case, a method of increasing the thickness of the structure has been generally used. However, it is clearly uneconomical to increase the thickness of the structure, especially for temporary work unrelated to the final structure, such as the freezing method.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned conventional problems, and an object of the present invention is to provide an underground stress relief groove capable of absorbing a stress generated in the ground near a structure. The purpose is to provide a construction method. Another object of the present invention is to provide a method for constructing an underground stress release groove, which can perform a freezing method without adversely affecting a structure.

[0005]

Means for Solving the Problems In order to achieve the above object, a method of constructing an underground stress relief groove according to the present invention comprises the steps of: drilling a plurality of holes in the ground in parallel; Inside, the jet nozzle descends to the middle position, and the high pressure fluid from this nozzle excavates between adjacent holes and gradually raises the nozzle while connecting between the holes, stress absorbing this connection space A space is constructed, and the stress absorption space is filled with a displacement absorbing material in which styrene foam particles are covered with clay.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of the underground stress relief groove according to the present invention will be described below with reference to the drawings by way of an example in which the method is used for freezing.

<A> Drilling A plurality of holes 1 are drilled vertically and parallel from the ground near the shaft where the freezing method is applied. As this drilling method, various conventional methods for holding the hole wall using muddy water can be adopted. The diameter of the hole 1 is large enough to easily insert the jet nozzle. The hole 1 is drilled to a position slightly deeper than the lower part of the displacement absorbing space 2 described later.

<B> Construction of Displacement Absorbing Space 2 When a plurality of holes 1 are drilled in the ground in parallel, the jet nozzle 3 is lowered into the hole 1 to a position on the way. The nozzle 3 has an injection port in one direction or multiple directions, and uses a pump capable of pumping a large amount of water at a pressure of about 100 kgf / cm ² as a power source. When the nozzle 3 is lowered into one hole 1, a pipe 4 for discharging the earth is inserted into the hole 1 adjacent to the hole 1. The descending position of the jet nozzle 3 is
It is lowered not to the deepest part of the hole 1 but to a predetermined intermediate position and stopped. Then, a jet is jetted in a horizontal direction toward the adjacent hole 1 at the pressure as described above.

When the nozzle 3 is gradually raised at a speed corresponding to the ground conditions and the injection conditions, the earth and sand between the adjacent holes 1 is blown off, and is sucked to the ground by the earth discharging pipe 4 in the adjacent holes 1. Be eliminated. Thus, a displacement absorption space 2 connecting the holes 1 is constructed. The excavation by the jet nozzle 3 may be performed completely to the ground position, or may be stopped halfway underground.

<C> Displacement Absorbing Material The space constructed by the high-pressure fluid from the nozzle 3 in this manner must have a stable wall surface without collapse for a long period of time. For this reason, it is common to fill the underground space with a stable liquid having a large specific gravity or an alternative material having a wall surface maintaining function to suppress the collapse of the wall. However, in the case of a general stable liquid, when the freezing method is started, the liquid is also frozen at the same time, so that the expansion pressure due to the freezing is transmitted to the surrounding ground and existing structures, and the above-described conventional problem is solved. Can't improve.

Therefore, in the method of the present invention, a displacement absorbing material is filled in place of the general stabilizing liquid. This displacement absorbing material
Use a material that does not freeze until the surrounding ground freezes and finishes expanding, or a material that can absorb the deformation caused by the deformation caused by the freezing expansion even if it freezes. With such a material, the ground displacement on the freezing side can be absorbed, and the displacement and the accompanying transmission of the force can be prevented.

As the displacement absorbing material, for example, a material obtained by covering styrene foam granules 5 with clay 51 or the like can be used. (FIG. 6) That is, the clay 5 is added to the styrofoam granules 5 having a diameter of several millimeters.
1 or bentonite 52 or a combination of both is used. By adjusting the thickness and mixing ratio of this coating and the weight of the styrene granules 5, the specific gravity of the normally used stabilizer (for example, 1.03 to 1.
06 or more).

<D> Action of Displacement Absorbing Material Since the styrofoam granules 5 themselves enclose air therein, they have excellent heat insulating properties, soundproofing and vibration-proofing properties. Also, when a large external pressure is applied, the expanded polystyrene particles 5 are easily crushed and deformed, and can absorb the external pressure. (FIG. 9) If time passes at low temperature, the styrene particles 5 themselves will freeze, but since they surround the air inside, they will be crushed and deformed even if subjected to external pressure after freezing, and can absorb the external pressure. It has the characteristic that. (FIG. 10)

<E> Filling of Displacement Absorbing Material A material having the above-described characteristics is filled in a space as a displacement absorbing material. For this purpose, first, the surface of the displacement absorbing material is wetted with water to exhibit lubricity. Before sufficient swelling, the liquid is supplied into the displacement absorbing space 2 using a grout pump or the like, and is replaced with the stable liquid that has been filled up to then. FIG. 7 shows a state immediately after the replacement, in which the clay 51 and the bentonite 52 surrounding the styrofoam fluid 5 are in contact with each other.

Thereafter, as time elapses, the clay 51 and bentonite 52 covering the periphery of the styrene particles 5 swell. At this time, if the amount of bentonite is too large, the bentonite itself develops an expansion pressure, which is contrary to the object of the present invention. Therefore, the amount of bentonite is set to fill the gap between the grains, and the weight is adjusted with ordinary clay there. After swelling in this way, the space between the styrofoam granules 5 is maintained. FIG. 8 schematically shows the state.
It is. In this way, it is possible to form a region filled with the displacement absorbing material at a required distance and thickness at a required position in the ground.

[0016]

As described above, the method of constructing the underground stress relief groove of the present invention has the following effects. <A> A large displacement absorption space 2 can be formed underground in a safe state only by providing a small opening without the need to cut a large scale. <B> The expansion of the ground due to freezing can be absorbed in the displacement absorbing space 2 and the influence on the structure can be cut off. Therefore, there is no need to increase the strength of the structure more than necessary, which is extremely economical. <C> By constructing the displacement absorbing space 2 in the ground, harmful vibrations propagating in the ground can be cut off, and can be used for a wide range of applications.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an embodiment of a method for constructing an underground stress release groove according to the present invention.

FIG. 2 is an explanatory diagram of a construction state.

FIG. 3 is an explanatory diagram of a construction state.

FIG. 4 is an explanatory diagram of a state after construction.

FIG. 5 is a perspective view of a construction state.

FIG. 6 is an explanatory view of an embodiment of a displacement absorbing material.

FIG. 7 is an explanatory diagram of a state immediately after the insertion replacement.

FIG. 8 is an explanatory view at the time of swelling.

FIG. 9 is an explanatory view when displacement is absorbed.

FIG. 10 is an explanatory view when the whole is frozen.

Continuing on the front page (72) Inventor Hiroshi Oya 1-25-1, Nishishinjuku, Shinjuku-ku, Tokyo Taisei Construction Co., Ltd. (72) Isao Hashimoto 1-25-1, Nishishinjuku, Shinjuku-ku, Tokyo Taisei (56) References JP-A-3-69737 (JP, A) JP-A-6-128942 (JP, A) JP-A-50-9906 (JP, A) JP-A-1-61278 (JP) , U) Jikken 48-6210 (JP, Y1) (58) Fields investigated (Int. Cl. ⁷ , DB name) E02D 31/14 E02D 3/12 101

Claims (2)

(57) [Claims] 1. A plurality of holes are drilled in parallel in the ground, a jet nozzle is lowered into the hole to an intermediate position, and a high pressure fluid from the nozzle excavates between adjacent holes. A method of constructing an underground stress release groove by gradually raising the nozzle while connecting the holes, constructing this connection space as a stress absorbing space, and filling this stress absorbing space with a displacement absorbing material 2. A plurality of holes are drilled in parallel in the ground, and a jet nozzle is lowered into the hole to an intermediate position, and a high pressure fluid from the nozzle excavates between adjacent holes. The nozzle is gradually raised while connecting the holes with each other, and this connecting space is constructed as a stress absorbing space, and the stress absorbing space is filled with a displacement absorbing material in which styrene foam particles are covered with clay. Method of construction of stress relief groove