JPH03279596A - Excavation method of large section or superlarge section of tunnel - Google Patents

Abstract

PURPOSE:To improve the efficiency of construction by providing plural headings inside or at the periphery of a scheduled excavation area, driving in soil-sewing bolts for main pit from each heading to the outside ot the area, and bolts for stabilizing facings into the area respectively, and excavating the inside of the area. CONSTITUTION:A top heading 2 is excavated on the top of a scheduled excavating area 1, a sticking concrete and a timbering are applied, and plural soil- sewing bolts 3 for main pit are driven in to the outside of the area 1, while plural bolts 7 for stabilizing facings are driven in to the area 1 respectively. Then, side wall headings 5 extending along the inside and the outside of the area 1 are excavated at both lower sides of the area 1, a spraying concreating and a timbering are applied, and plural soil-sewing bolts 6 for main pit and plural bolts 7 for stablizing facings are driven in, outside the area 1 and inside the area 1 respectively. And side wall concretes 8 are placed to secure the bottom wall of timbering. Then, the area 1 is excavated while removing the bolts 4 and 7, and a part of bolts 3 in the area 1. Consequently, the cost of construction can be reduced.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a construction method for excavating a tunnel with a large cross section or an extremely large cross section using a shaft.

[Conventional technology]

Currently, tunnels with an excavation cross section of 70 to 80 m are called standard tunnels, and tunnels with an excavation area of 100 to 120 m are called large cross section tunnels.
If a tunnel of 140M or more is called an ultra-large cross-section tunnel, especially in the case of an ultra-large cross-section tunnel, not only the excavation cross section becomes large, but also the aspect ratio (vertical length / horizontal length)
The stability of the ground becomes a particular issue as the size of the ground becomes smaller. For this reason, conventionally, in general, a divided excavation method was used in which an extremely large cross section is divided into smaller sections in the order of ■ to ■, as shown in Figures 3 (a) to C), respectively, and then excavated into smaller pieces, or as shown in Figure 4. The advanced method of construction of side wall shafts was used, in which side wall shafts were constructed on both sides, and the space between these shafts was supported against the ground using a highly rigid pipe roof or fore pile and a large excavation was made.

[Problem to be solved by the invention]

However, in the conventional divided cross-section excavation method and advanced sidewall tunnel construction method, the shoring used when excavating an extremely large cross-section was intended to stabilize the entire cross-section at once, and large-scale shoring was required. In particular, the advanced sidewall tunnel construction method requires auxiliary construction methods such as pipe roofing and forepiling, which poses the problem of increased construction costs. In addition, in the past, there was a method of constructing seam bolts from the divided section excavation space or the guide shaft, but this was only for stabilizing the divided section excavation space or the guide shaft itself, and the length was short and the number of bolts was small. Due to the small number of piles, it was not possible to stabilize the pile. Furthermore, there was a method of constructing vertical seam bolts from the ground surface to the top of the tunnel, but this method had the problem of limiting the applicable location and construction depth. In view of these conventional problems, the present invention can easily stabilize the ground around large-section or extra-large-section tunnels, and can also ensure the stability of the face of the pile in advance. The purpose of the present invention is to provide an excavation method that can reduce the size of the shoring and perform the main pile excavation efficiently and economically in a stable condition.

[Means to solve the problem]

In the present invention, a plurality of guide shafts are provided in or around the area where a large-section or extra-large-section tunnel is scheduled to be excavated, and a seam bolt for the main shaft for the large-section or extra-large cross-section tunnel is inserted from each guide shaft into the area scheduled to be excavated. After penetrating the face stabilizing bolt outward into the area to be excavated, the area to be excavated is excavated while the face stabilizing bolt is scattered.

[For production]

The seam bolts for the main pile that penetrate through multiple guide shafts increase the shearing force of the surrounding ground and minimize loosening during excavation of the main pile, and longitudinally, bolts for stabilizing the main pile face are installed in front of the main pile face. is struck in advance, ensuring the stability of the face.

【Example】

Hereinafter, one embodiment of the present invention will be described based on the drawings. As shown in Figure 1, a small cross-section (
For example, diameter 4. Excavate a top shaft 2 (approximately 1000 ft), spray concrete and shoring, and from the top shaft 2, install multiple bolts 3 for main piles outside the planned excavation area 1, and install concrete and shoring. 1, a plurality of bolts 4 for stabilizing the face are inserted thereinto. In addition, side wall guide shafts 5 with a small cross section (same as above) are excavated in the lower left and right sides of the planned excavation area 1, extending inside and outside the area, and sprayed concrete and shoring are constructed in each side wall guide shaft 5. A plurality of seam bolts 6 for the main shaft are penetrated to the outside of the planned excavation area 1, and a plurality of face stabilization bolts 7 are penetrated into the planned excavation area 1, and side wall concrete 8 is poured to form a supporting bottom wall in advance. Secure it. In addition, among the seam bolts 3.6 for the main pile, those that will remain after the construction of the main pile is completed, as described later, are, for example, 6.0 to 10.0 m.
However, it is preferable that some seam bolts and face stabilizing bolts 47 that are removed during the actual pile excavation be FRP rods with a length of about 4.0 to 6.0 m. Next, as shown in Fig. 2, while removing the face stabilizing bolts 4゜7 and some of the main pile seam bolts 3 in the planned excavation area 1, the entire cross section or divided cross section of the planned excavation area 1 is removed. excavate with. In this case, since the surrounding ground of the planned excavation area 1 has been reinforced in advance with the seam bolts 3.6 for the main piles, the shoring can be made small-scale and the effort of installing seam bolts again can be saved. Moreover, since the face stabilizing bolts 4.7 are installed in the planned excavation area 1, the stability of the face can be ensured in advance. Next, sprayed concrete and shoring were applied to the left and right sidewalls (8 spaces), and if necessary, bolts for the main piles were driven, and then an arch-shaped lining 9 was installed, and inverted concrete was installed. 0 to complete the super large cross section tunnel. In addition, in the above embodiment, an ultra-large cross-section tunnel was used as an example, but
It goes without saying that the present invention can also be applied to large-section tunnels.

【Effect of the invention】

According to the present invention, there are the following effects. ■ Before excavating a tunnel with a large or very large cross section, the surrounding ground is reinforced with seam bolts that are left as is for the main pile, so the main pile can be excavated with a large cross section. ■ Shoring can be made small-scale and economical. ■ The face can be stabilized before the actual pile excavation. ■ There is no need to install seam bolts again when excavating the actual pile.

[Brief explanation of drawings]

Figures 1 and 2 are explanatory diagrams of one embodiment of the present invention, Figures 3 (a) to (C) are conceptual diagrams of the conventional split excavation method, respectively, and Figure 4 is the conventional advanced side wall tunnel construction method. It is a conceptual diagram. 1... Area to be excavated, 2... Top guide shaft, 3, 6... Sewing port for wooden piles, 4.7...
... Face stabilization bolt, 5 ... Side wall guide shaft, 8
...Side wall concrete, 9... Lining,
10... Invert concrete. Figure (0) Figure (b) Figure (C) Figure Figure 2

Claims (1)

[Claims] 1. Provide multiple guide shafts in or around the area where the large-section or extra-large-section tunnel is scheduled to be excavated, and from each guide shaft move the seam bolts for the main shaft for the large-section or extra-large cross-section tunnel out of the area where the tunnel is planned to be excavated. , and a method for excavating a tunnel with a large cross section or a very large cross section, characterized in that after a bolt for stabilizing the face is penetrated into the region to be excavated, the region to be excavated is excavated while the bolt for stabilizing the face is being scattered.