JP2000073697A - Leg pile method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve workability in leg pile method and to make leg piles effective certainly even after placement of lining concrete. SOLUTION: On the occasion of making an arched timbering 1, a support metal 10 is fixed beforehand. After the arched timberings 1, 1... are installed at specified intervals in the direction of tunnel excavation, a leg pile 2 is placed into an opening 10a of the support metal 10 with a boring machine. Cement milk is injected into the inside of the leg pile 2, and a gap between the inside of the support metal 10 and the head part 2a of the leg pile is filled with high strength mortar and the support metal 10 and the head part 2a of the leg pile are stuck together.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leg pile method for supporting arch support of a tunnel, and more particularly to a leg pile method for ensuring a pile effect and preventing settlement.

[0002]

2. Description of the Related Art In a road section tunnel, when the geology is poor ground such as earth and sand ground, the supporting leg portion of the upper half section may be settled. It may not be possible or may hinder the stability of the tunnel itself. As an auxiliary construction method for preventing this, a leg pile construction method is known.

In the leg pile method, as shown in FIGS. 4 and 5, arch supports 1, 1,... Are provided at predetermined intervals in a tunnel excavation direction (the direction of arrow S in FIG. 5). Next, a leg pile 2 is placed in the ground in the lower half of the tunnel. Then, after injecting the cement milk into the inside of the leg pile 2, the head 2 a of the leg pile is supported by the receiving girder 3 attached to the arch support 1. Further, a reinforcing bracket 4 is fixedly mounted on the upper part of the receiving girder 3. In this manner, the lower half of the tunnel is excavated while the upper half ground load is transmitted to the leg pile 2.

[0004]

As described above, the leg pile 2 cast into the ground in the lower half of the tunnel can prevent the arch support 1 from sinking. But,
Since the installed girder 3 and the reinforcing bracket 4 enter the thickness of the lining concrete 5, the girder 3 and the reinforcing bracket 4 must be removed before the waterproof sheet is stretched, and the removal work is complicated. In addition, the transmission of the upper mountain ground load is impaired.

[0005] Therefore, there is a technical problem to be solved in order to improve the workability in the leg pile method and to ensure that the pile effect can be exerted even after the lining concrete is constructed. The invention aims to solve this problem.

[0006]

SUMMARY OF THE INVENTION The present invention has been proposed to achieve the above-mentioned object. In order to support an upper half section of a tunnel, arch supports are provided at predetermined intervals in an excavation direction, and the arch supports are provided. In the leg pile method in which a leg pile is cast into the ground in the lower half of the tunnel adjacent to the work and the head of the leg pile is supported by the arch support, the leg pile is previously attached to the arch support. After fixing a receiving bracket into which the head can be inserted, and providing arch supports at predetermined intervals in the tunnel excavation direction, a leg pile is driven into the receiving bracket by a drilling machine, and the receiving bracket is mounted. The present invention provides a leg pile method in which the head and the head of the leg pile are fixed with a high-strength mortar.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to FIGS. In the present invention, when the arch support 1 is manufactured, the receiving metal fitting 10 is fixed in advance.
The receiving fitting 10 has an opening 10a into which the head 2a of the leg pile can be inserted. Reference numeral 11 denotes a backing plate (steel plate) fixed to the arch support 1, and the receiving fitting 10 is attached via the backing plate 11.

After the arch supports 1, 1... Are installed at predetermined intervals in the direction of excavation of the tunnel, the legs are inserted into the opening 10a of the receiving fitting 10 by using a drilling machine (not shown). Pile 2 is placed. Then, cement milk is injected into the inside of the leg pile 2, and a high-strength mortar 1 is inserted into a gap between the inside of the receiving metal fitting 10 and the head 2 a of the leg pile.
1 and the receiving fitting 10 and the head 2 of the leg pile.
a.

Although not shown, in order to facilitate the passage of the bit of the drilling machine and the fixing work of the leg pile 2,
A guide tube is inserted outside the leg pile 2 so that the inside of the receiving fitting 10 has a double pipe structure.
After welding to the inside portion of the mortar 0, the gap in the receiving fitting 10 may be filled with the high-strength mortar 11.

Thus, the lower half excavation of the tunnel can be performed in a state where the arch support 1 and the leg pile 2 are integrated, and the upper half ground load is reliably transmitted to the leg pile 2. And since the said receiving metal fitting 10 hardly protrudes into the winding thickness of the lining concrete 5, it can remain as it is. Therefore, it is not necessary to perform a complicated removal work unlike the conventional girder or auxiliary bracket, and the transmission of the upper half ground load is not impaired.

Incidentally, by fixing receiving brackets 10, 10 on both sides of the arch support 1 and driving the leg piles 2, 2 across the arch support 1, the pile effect is further improved. Large-section tunnels can be constructed on soils.

Thus, the present invention can be variously modified without departing from the spirit of the present invention, and it is natural that the present invention extends to the modified ones.

[0013]

According to the present invention, as described in detail in the above-mentioned embodiment, a receiving bracket is fixed to an arch support in advance, and the head of a leg pile is driven into the ground in the lower half of the tunnel. Is fixed to the receiving fitting, the arch support and the leg pile are integrated through the receiving fitting, so that the upper half load of the tunnel can be received by the leg pile and the arch support can be prevented from sinking. In addition, there is no complicated removal work as in the case of the conventional girder or auxiliary bracket, and the upper half load of the tunnel can be continuously transmitted to the leg pile even after the lining concrete is constructed.

[0014] Thus, the present invention provides various effects, such as improved workability in the leg pile method and a reliable pile effect even after the lining concrete is constructed.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is a side view of FIG. 1;

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is a front view showing a conventional technique.

FIG. 5 is a side view showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Arch support 2 Leg pile 2a Leg pile head 10 Receiving bracket 10a Opening 11 High strength mortar

Claims (1)

[Claims] 1. An arch support is provided at predetermined intervals in an excavation direction to support an upper half section of a tunnel, and a leg pile is cast into the ground in a lower half of the tunnel adjacent to the arch support. In the leg pile method in which the head of the leg pile is supported by the arch support, a receiving bracket into which the head of the leg pile can be inserted is fixed to the arch support in advance and a predetermined direction is defined in the tunnel excavation direction. After the arch supports are provided at intervals, a leg pile is driven into the receiving bracket by a drilling machine, and the receiving bracket and the head of the leg pile are fixed with a high-strength mortar. Pile method.