JP2932197B2 - Excavation method for large or very large tunnel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a method for excavating a tunnel having a large cross section or a very large cross section using a pit.

^2. Description of the Related Art It is now assumed that a tunnel having an excavation cross section of 70 to 80 m ² is called a standard tunnel, a tunnel of 100 to 120 m ² is called a large section tunnel, and a tunnel of 140 m ² or more is called a super large section tunnel.
Particularly in the case of a tunnel having a very large section, not only the excavated section becomes large, but also the flattening ratio (vertical length / horizontal length) becomes small, so that the stability of the ground is particularly problematic. For this reason, in the prior art, generally, the excavation method shown in FIGS. 3a to 3c has a super-large cross-section, and is excavated by dividing the excavation into smaller pieces, or as shown in FIG. After the construction, an advanced side wall tunneling method was adopted in which a large excavation was carried out while supporting the ground using a highly rigid pipe roof or fore piling.

[Problems to be solved by the invention]

However, in the conventional split section excavation method and the side wall advanced shaft excavation method, the support at the time of the super-first section excavation is intended to collectively stabilize the entire section, and a considerably large-scale support is required. In particular, the advanced sidewall construction method requires an auxiliary construction method such as a pipe roof or a fore piling, and has a problem that the construction cost is increased. Also, in the past, there was a method of constructing the sewing ground bolt from the divided section excavation space and the pit, but it was only to stabilize the divided section excavation space and the pit itself,
Because of the short length and the small number, the pit could not be stabilized. Furthermore, there was a method of constructing a vertical sewing bolt from the ground surface to the top end of the tunnel, but there was a problem that the application place and the construction depth were limited. In view of such conventional problems, the present invention can easily stabilize the ground around a large-section or super-large-section tunnel, and can also ensure the stability of the face of the main pit in advance,
Accordingly, it is an object of the present invention to provide an excavation method capable of reducing the size of the support pit of the main pit and performing the pit excavation in a stable state efficiently and economically.

[Means for Solving the Problems]

In the present invention, a plurality of pits are provided in or around the excavation area of the large-section or super-large section tunnel, and a main pit sewing ground bolt for a large-section or super-large section tunnel is provided from each of the pits in the above-mentioned excavation area. After the face stabilizing bolt is penetrated outside and into the area to be excavated, the area to be excavated is excavated while removing the face stabilizing bolt.

[Action]

With the ground bolt for main shaft penetrated from multiple shafts,
Increases the shearing force of the surrounding ground to minimize loosening etc. during excavation of the main pit, and in the longitudinal direction, a face stabilizing bolt will be hit in advance in front of the main pit face, ensuring the stability of the face it can.

【Example】

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, an excavation tunnel 2 having a small cross section (for example, about 4.0 m in diameter) is excavated at the top of an excavation area 1 of a super-large cross section tunnel (main shaft) to be finally constructed. Pile concrete and shoring work are carried out, and a plurality of main shaft sewing bolts 3 and a plurality of face-face stabilizing bolts 4 penetrate from the top pit 2 to the outside of the planned excavation area 1. .
In addition, excavation of a side tunnel 5 having a small cross section (the same degree as described above) extending inside and outside the lower left and right sides of the planned excavation area 1,
Shotcrete and shoring work are carried out in each of the side wall tunnels 5, a plurality of main shaft sewing bolts 6 are provided outside the planned excavation area 1, and a plurality of face stabilizing bolts 7 are provided in the planned excavation area 1. , And the side wall concrete 8 is poured in to secure the support bottom wall in advance. The bolts 3 and 6 left behind after the completion of the construction of the main pit, as described later, are steel rods of, for example, about 6.0 to 10.0 m. The sewing bolt and the face stabilizing bolts 4, 7 are preferably FRP rods of about 4.0 to 6.0 m. Next, as shown in FIG. 2, while removing the face stabilizing bolts 4 and 7 and a part of the main pit sewing ground bolt 3 in the planned excavation area 1, the entire cross section or the divided cross section in the planned excavation area 1 is removed. Excavate with In this case, the ground around the planned excavation area 1 is reinforced in advance with the main pit sewing bolts 3 and 6, so that the support pit can be reduced in size and the labor for newly constructing the sewing bolts can be omitted. In addition, since the face stabilizing bolts 4 and 7 are installed in the excavation area 1, the stability of the face can be secured in advance. Next, spraying concrete and shoring work are carried out between the left and right side wall concretes 8, and furthermore, after digging bolts for main shaft pits as necessary, lining 9 is constructed in an arch shape, and invert concrete 10 is also formed. Cast and complete a super large section tunnel. In the above embodiment, a super large section tunnel is taken as an example, but it goes without saying that the present invention can be applied to a large section tunnel.

【The invention's effect】

According to the present invention, the following effects can be obtained. Before excavation of a large-section or super-large-section tunnel, a main section excavation can be performed on a large section because the surrounding ground is reinforced in advance by sewing bolts left as it is for the main tunnel. The support pit can be made small and economical. Since the face stabilizing bolt penetrates into the area to be excavated, the face can be stabilized before excavating the main pit. It becomes unnecessary to construct sewing bolts again when excavating the main shaft. Face stabilization bolts are prepared separately from the main pit sewing bolts left outside the main pit even after excavation, and the face stabilization bolts penetrate only into the planned excavation area and are removed when excavating the main pit. In addition, the work of penetrating and removing the face stabilizing bolt can be easily performed.

[Brief description of the drawings]

1 and 2 are explanatory views of one embodiment of the present invention, FIGS. 3a to 3c are conceptual diagrams of a conventional split excavation method, respectively, and FIG. 4 is a conceptual diagram of a conventional advanced side wall tunneling method. is there. 1 ... Excavation area, 2 ... Top pit, 3,6 ... Soil bolt for main pit, 4,7 ... Bolt for stabilizing face, 5 ... Sidewall tunnel, 8 ... Sidewall concrete, 9 ... lining, 10 ... invert concrete.

Claims (1)

(57) [Claims] 1. A plurality of tunnels, at least a part of which is located in an area to be excavated in a large or ultra-large section tunnel, and a plurality of main shaft sewing materials for a large or ultra-large section tunnel from each of the tunnels. After penetrating the bolts out of the planned excavation area, and penetrating a plurality of face stabilizing bolts different from the main shaft sewing bolt only in the planned excavation area, while removing the face stabilizing bolts, An excavation method for a tunnel having a large cross section or a very large cross section, wherein the tunnel is excavated in an area to be excavated.