JP2597298B2 - Preceding method for the ground in front of the tunnel face - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excavation work in a tunnel, such as a road, a railroad, and a waterway, in a case where there is little earth covering, or in a weak ground where the face is independant and highly collapsible. In this regard, the present invention relates to a front receiving method for a ground in front of a tunnel face to prevent collapse of the face and collapse of a top end.

[0002]

2. Description of the Related Art In a pre-mounting method for a ground in front of a tunnel face, a pre-installation method is used.
There is a prelining method for excavation. In addition, inside or outside the tunnel excavation area, after digging the pit prior to digging the main pit, always before the pit excavation, inject various chemicals from the inside of the pit into the outer circumference of the pit excavation, and There is also a construction method in which main digging is performed after the outer periphery is consolidated.

[0003] The former has a high reliability with respect to the stability of the ground, but has a problem in that the excavation work must be interrupted during the pre-installation work, so that the work efficiency is reduced.
In the latter case, the work can be performed without affecting the excavation work, but the reliability of the stability of the ground is poor with general chemical injection, and the cost increases if a highly reliable chemical is used. There is a problem.

[0004]

The problem to be solved by the present invention is to perform the excavation work of the main pit without interruption while ensuring the reliability of the stability of the ground, and at a relatively low cost. Is to do.

[0005]

The features of the present invention are as follows. In the tunnel excavation, a pit excavation is performed immediately above the top of the main mine to be excavated, prior to the main mine excavation. The consolidation layer is formed diagonally right and left in the direction of excavation from the inside of the shaft, and lining of the shaft is performed.

[0006]

A pit is provided immediately above the top of the main pit prior to the main pit excavation, and a solidified layer is formed to cover the planned outer circumference of the main pit excavation while always preceding the main pit excavation. As a result, the excavation of the main pit can be performed without interruption while ensuring the reliability of the stability of the ground. Moreover, since there is no need for expensive chemical injection,
Can be constructed relatively inexpensively.

Here, the concept of the support of the method of the present invention will be described. The consolidated layer undergoes a deformation similar to a beam on an elastic floor due to the ground pressure from above, and is above the consolidated layer in the tunnel excavation direction. A transverse ground arch is formed.
At the same time, in addition to the occurrence of pressure bulbs due to the ground reaction force below the consolidated layer tip, the stability of the lateral ground can be obtained due to the effect of introducing prestress into the ground during the consolidated layer construction.

[0008] Also, the deformation of the shaft similar to a beam on an elastic floor creates a longitudinal ground arch. At the same time, the face is stabilized by the pressure bulb due to the ground reaction force in front of the face and the effect of introducing prestress into the ground at the time of consolidation layer construction.

Further, in the main shaft excavation portion, the settlement of the upper shaft is prevented by supporting the solidified layer and supporting the main shaft excavation portion, thereby stabilizing the surrounding ground.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIGS. 1 to 3, reference numeral 1 denotes a ground pile, 2 denotes a main shaft of a tunnel, 3 denotes a face of the tunnel, and 4 denotes a lining of the main shaft 2. 5 is a shaft excavated just above the top of the main shaft 2, and 6 is its lining. The shaft 5 is excavated prior to the excavation of the main shaft 2.

Prior to the lining operation, a plate-shaped solidified layer 7 covering the excavation perimeter of the main shaft 2 is formed by the high-pressure injection method in the shaft 5. The consolidation layer 7 is formed in contact with or close to the excavation perimeter line of the main shaft 2 obliquely downward and leftward in the excavation direction a from inside the shaft 5. In the case of the embodiment, a paste-type cement-based hardening material is injected by using a high-pressure injection column-column pile forming apparatus 11, and the column-column piles 8, 8, 8, ... are formed in a roof shape so as to overlap each other. I do. .. Are reinforced with steel bars or steel pipes, respectively, and are connected and fixed to the lining 6 of the shaft 5 with nuts.

The solidified layer 7 can be formed by stacking the column rows 8, 8, 8,... By a mechanical stirring method instead of the embodiment.

As described above, always prior to the excavation of the main shaft 2,
The main shaft 2 is excavated while forming the consolidated layer 7. Main shaft 2
Lining work and supporting work are performed by known methods.

[0014]

According to the present invention, since the excavation of the main pit is not interrupted, the construction period can be shortened. In addition, since a solidified layer is formed to cover the planned outer circumference line of the main pit prior to the excavation of the main pit, the reliability of the ground stability can be improved. And the safety of tunnel excavation work can be ensured.

No more expensive chemicals or special machines are required.
In addition, since a large cross section can be excavated and the construction period can be shortened, construction can be performed at a relatively low cost.

Further, since the shaft can be finally used as a ventilation shaft or the like, the tunnel section can be effectively used.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a main shaft, a shaft, and a consolidated layer.

FIG. 2 is a schematic side view showing a state of excavation of a tunnel.

FIG. 3 is a side view of a lining shaft and a consolidated layer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ground mountain 2 Main shaft 3 Face 5 Guide shaft 7 Solidified layer

Claims (2)

(57) [Claims] In the excavation of a tunnel, a pit excavation is performed immediately above the top end of the main mine to be excavated, prior to the main mine excavation. A front receiving method for a ground face in front of a tunnel face, in which a plate-like solidified layer is formed obliquely downward and leftward in the direction of excavation from inside a shaft and lining of the shaft is performed. 2. The method of claim 1, wherein the consolidation layer is formed continuously by stacking column piles formed by a high-pressure injection method so as to overlap each other.