JPH11229366A - Preventing method for collapse of natural ground - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the collapse of natural ground by coupling the area forecasted to collapse with a stable area. SOLUTION: In a step 101, the area forecasted to collapse is determined through subsoil exploration, and in a step 102 a vertical shaft is bored in a stable area. In a step 103, a plurality of injection holes are bored from the vertical shaft toward the area forecasted to collapse, and in a step 104, once the ends of the injection holes have reached a surface assumed to collapse, a chemical is injected into the ends of the injection holes from the surface of the ground via a vertical hole and the injection holes. The operations in the steps 102 through 104 are regarded as one cycle, and this cycle is repeated until the injection of the chemical into the area forecasted to collapse is sufficient. In a step 105, a drain hole is bored in the stable area from the lowermost vertical shaft, and in a step 106 a boring machine, a chemical tank, and other machines and facilities are removed to finish measures.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing ground collapse in advance.

[0002]

2. Description of the Related Art The land area of Japan is small and the mountains are steep, so that the mountains are likely to collapse in mountainous areas.

[0003]

In order to prevent the collapse of the ground, it is necessary to crush the collapse prediction area where the collapse is predicted by the ground survey, or to improve the ground with the chemical injection. However, crushing has a large effect on the surrounding environment, and chemical injection may cause a crack to occur or expand at the boundary between the collapse prediction area and the stable area, causing collapse. At the same time, it is difficult to easily adopt the safety of the construction and the effect of improvement to improve the entire supposed collapsed surface requiring improvement.

[0004] Therefore, the present invention provides a method for excavating an injection hole from a shaft in a stable area to a predicted collapse area, and using the shaft and the injection hole to allow a drug to penetrate into a crack on a supposed collapse surface and around the crack. It is an object of the present invention to provide a method for preventing the collapse of the ground which can combine the predicted collapse area with the stable area while preventing the occurrence and expansion of the ground.

[0005]

According to the first aspect of the present invention, a shaft is excavated in a stable area around a collapse prediction area, and an injection hole is excavated from the shaft toward the collapse prediction area.
When the injection hole reaches a supposed collapse surface at the boundary between the collapse prediction area and the stable area, the agent is injected and hardened into the injection hole. According to the second aspect of the present invention, the excavation of the shaft, the excavation of the injection hole, and the injection of the chemical according to the first aspect are performed in one cycle, and the injection of the chemical into the predicted fall area can secure the stability of the entire ground. It is characterized by repeating until The invention of claim 3 is characterized in that a drain hole is excavated from the shaft of claim 1 and is used as a drainage channel for groundwater without backfilling the shaft and the drain hole.

[0006]

1 to 4 show an embodiment of the present invention. FIG. 1 shows a process, FIG. 2 shows a side view of a countermeasure, FIG. 3 shows a plan view of the countermeasure, FIG. 4 shows an example of drug injection.

Referring to FIG. 1, a method for preventing the collapse of the ground will be described. In step 101, a collapse prediction area and an assumed collapse surface where rocks of the ground are predicted to collapse by the ground survey are determined, and in step 102, a shaft is excavated in a stable area behind the collapse prediction area. In the case of this embodiment, the excavation operation is controlled so that the shaft is prevented from collapsing due to the impact during excavation and the ground around the shaft is excavated (step 103) and the injection operation of the injection hole described later and the chemical injection operation. Excavation is performed for a predetermined depth of one cycle, for example, about several meters so that (Step 104) can be easily performed. Then, in step 103, a plurality of injection holes are excavated radially by boring from the shaft to the collapse prediction area. In boring, excavation work such as excavation speed and bit rotation speed is controlled so that the collapse prediction area does not collapse due to the impact during excavation. Then, in step 104, when the tip of the injection hole reaches the assumed collapsed surface or penetrates the assumed collapsed surface, the medicine is transferred from the medicine tank previously set on the ground surface through the shaft and the injection hole to the tip of the injection hole. Inject into

After that, returning to step 102, a shaft following the bottom of the preceding shaft is excavated to a predetermined depth, and step 10 is performed.
In Step 3, a plurality of injection holes are drilled radially by drilling from the succeeding shaft toward the collapse prediction area.
In step 4, when the tip of the subsequent injection hole reaches the assumed collapsed surface or penetrates through the assumed collapsed surface, the medicine is injected into the tip of the injection hole. Further, the operations of steps 102 to 104 are repeated, and the medicine injection into the collapse prediction area becomes sufficient, and the medicine spreads to the crack in the assumed collapse surface and the surrounding ground, and when the stability of the whole ground is sufficiently ensured. , Step 10
The repetition of steps 2 to 104 is stopped. And step 1
At 05, a drain hole is excavated from the lower shaft to a stable area, and at step 106, the boring machine, the chemical tank and other equipment and facilities are removed, and the countermeasures are completed.

As described above, the medicine injected before and after the assumed collapsed surface in the injection hole penetrates into the cracks in or around the assumed collapsed surface, and the chemicals penetrates into the injection hole and the cracks. In addition, the hardened medicine has a form in which the collapse prediction area is bonded to the stable area, and the collapse of the rock can be prevented. Moreover, there is a permeation-hardened chemical agent in the crack and its surroundings, and after the countermeasures, rainwater and groundwater hardly penetrate into the crack and its surroundings, and the generation and expansion of the crack can be prevented. In addition, by using the shaft as a groundwater collecting hole without backfilling, the landslide prediction area and surrounding groundwater are appropriately drained to the outside through the drainage hole from the shaft, and the ground in the landslide prediction area is reduced. It is possible to prevent instability due to repetition of wet and dry or wet.

[0010] It is preferable that the injection pressure at the time of injecting the drug is in a range where the crack is not enlarged. In addition, as a drug, it has characteristics of low viscosity, small swelling property upon curing and swelling property due to temperature change, long gel time of several days, good permeability, and little decrease in strength with time. For example, any of a solution type (chemical system such as water glass and a polymer type) and a suspension type (cement type) can be used. In the case of the suspension type, cement particles are ultrafine particles. The use of a certain microcement ensures good penetration of chemicals into the ground and cracks, and is stable over time after construction.

In FIGS. 2 and 3, 1 is a predicted collapse area, 2 is a stable area, 3 is an assumed collapse surface, 4 is a shaft, 5 is an injection hole, and 6 is a drain hole. And in FIG. 2,
The shaft 4 and the injection hole 5 are placed in the first 1
The shaft 4A and the injection hole 5A excavated in the cycle, the shaft 4B and the injection hole 5B excavated in the second one cycle as shown by the dashed line, and the third one cycle as shown by the phantom line The excavated shaft 4C and the injection hole 5C are shown. One cycle in the first to third times corresponds to the operation of steps 102 to 104 in FIG.
Therefore, the stability of the predicted collapse area 1 during the subsequent work can be ensured by connecting the predicted hardened area 1 to the stable area 2 from the ground surface side every time one cycle of operation. Then, when the countermeasure is completed, the hardened medicine becomes a form in which the collapse prediction area 1 is adhered to the stable area 2 and the stability of the whole ground can be secured.
Reference numeral 7 denotes a road or a railway.

When the hole 8 does not collapse during injection of the drug 8 into the injection hole 5, as shown in FIG. 4, the rod 10 is removed after the excavation is completed, and the injection pipe in which the packer 11 is mounted at a predetermined position is provided. (Double tube) 12 is inserted into the injection hole 5,
Air or water is injected into the packer 11 via the outer pipe of the injection pipe 12 to be inflated and adhered to the hole wall. Then, the medicine 8 is filled from the side of the shaft 4 into the tip 5a of the excavation hole 5 via the inner pipe of the injection pipe 12, and the medicine 8 penetrates into the assumed collapsed surface 3 around and the cracks around it. When the permeation of the medicine 8 is completed, the air or water in the packer 11 is drained, and the injection pipe 12
To remove. However, when there is a possibility that the hole wall is not stable and collapses, the injection hole 5 is excavated while inserting a casing (not shown), and the subsequent work is performed in the same manner as when the hole wall does not collapse.

In the above embodiment, the excavation of the shaft 4 and the injection hole 5
The excavation and chemical injection were repeated as one cycle of work, but as shown in FIG. 5, the shaft 4 was excavated to a depth at which the stability of the entire ground could be secured by injection of the chemical into the collapse prediction area 1, and thereafter, The injection hole 5 may be drilled toward the collapse prediction area 1, and the medicine may be injected into the injection hole 5 in an arbitrary order according to the state of the collapse prediction area 1.

In the above-described embodiment, the medicine is guided to the tip end of the injection hole 5 by the member. However, as shown in FIG. 6, the shaft 4 is excavated to a depth at which the medicine injection into the collapse prediction area 1 is sufficient. Then, the injection hole 5 may be excavated toward the collapse prediction area 1, and thereafter, the chemical 8 may be injected into the shaft 4, so that the chemical may be naturally permeated into the injection hole 5 from the shaft 4.

[0015]

As described above, according to the first aspect of the present invention, the injection hole is excavated from the shaft excavated in the stable area around the predicted collapse area toward the predicted collapse area, and the injection hole is formed around the assumed collapse surface. By injecting and hardening the chemical, it is possible to prevent the occurrence and expansion of cracks, connect the predicted collapse area to the stable area, and secure the stability of the entire ground. According to the invention of claim 2, the excavation of the shaft, the excavation of the injection hole, and the chemical injection are performed in one.
By repeatedly connecting the collapse prediction area to the stable area from the ground surface side as the work of the cycle, the stability of the collapse prediction area at the time of the subsequent work can be ensured. According to the third aspect of the present invention, the drainage hole is excavated from the shaft, and the groundwater and the drainage hole are used as a drainage channel for the groundwater without being backfilled, thereby appropriately draining the collapse prediction area and the surrounding groundwater. In addition, it is possible to prevent instability due to repetition of wet and dry or the like of the ground in the collapse prediction area and wetness.

[Brief description of the drawings]

FIG. 1 is a process chart of a first embodiment.

FIG. 2 is a schematic view showing a cross section from the side of the countermeasure according to the first embodiment.

FIG. 3 is a plan view of a countermeasure according to the first embodiment.

FIG. 4 is a sectional view of a medicine injection part according to the first embodiment.

FIG. 5 is a side view of a countermeasure according to the second embodiment.

FIG. 6 is a side view of a countermeasure according to a third embodiment.

[Explanation of symbols]

 1 Collapse prediction area 2 Stable area 3 Assumed collapse surface 4 Vertical shaft 5 Injection hole

Claims (3)

[Claims] 1. A shaft is excavated in a stable area around a collapse prediction area, an injection hole is excavated from the shaft toward the collapse prediction area, and at least the injection hole is assumed to have a boundary between the collapse prediction area and the stable area. A method for preventing collapse of the ground, which comprises injecting and hardening a drug into an injection hole when the temperature reaches a predetermined value. 2. The method according to claim 1, wherein the excavation of the shaft, the excavation of the injection hole, and the injection of the chemical are performed in one cycle, and the injection of the chemical into the collapse prediction area is repeated until the stability of the entire ground can be ensured. How to prevent land collapse. 3. The method according to claim 1, wherein a drain hole is excavated from the shaft and the ground hole and the drain hole are used as groundwater drainage channels without being backfilled.