Construction method and structure of two-layer preliminary support for preventing geological disaster of large-section weak surrounding rock tunnel

Abstract

The invention belongs to the construction method and structure of two-layer preliminary supports for preventing a geological disaster of a large-section weak surrounding rock tunnel. The construction method based on a three-step tunnel construction method comprises the first step of constructing advance supports of the tunnel, the second step of constructing top-heading first-layer preliminary supports of top headings, the third step of constructing center-heading first-layer supports and center-heading second-layer preliminary supports of center headings, the fourth step of constructing top-heading second-layer preliminary supports of the top headings, the fifth step of constructing bottom-heading first-layer preliminary supports and bottom-heading second-layer preliminary supports of bottom headings and the sixth step of constructing inverted arches, so supporting structures of closed rings of steel arches in the preliminary supports on all layers are formed. According to the construction method and structure, the geological disaster of the large-section weak surrounding rock tunnel can be effectively prevented, the safety of tunnel construction and operation is guaranteed, and economic loss caused by the geological disaster is reduced; besides, the construction method and structure have the advantages of being low in construction resource amount and cost, construction is easy, the construction speed is high, safety risks are small, and construction quality is high.

Description

technical field [0001] The invention belongs to a construction method and structure for double-layer initial support of a large-section weak surrounding rock tunnel to prevent geological disasters from occurring. Background technique [0002] At present, in tunnel construction, a tunnel with an excavation height of more than 10 meters, an excavation width of more than 10 meters, and a tunnel length of more than 1,000 meters is called a large-section super-long tunnel, or a large-section tunnel for short. Large-section tunnels are easier to construct in vertically solid rock landforms, but if they belong to denuded hilly landforms, the terrain has large undulations, well-developed joints, and many cracks. The irregular distribution of mud and black mudstone has a great impact on the stability of rock mass, leading to more geological disasters. [0003] Tunnel construction in the above-mentioned landforms not only increases the difficulty of tunnel construction and hidden saf...

AI Technical Summary

Problems solved by technology

Large-section tunnels are easier to construct in vertically solid rock landforms, but if they belong to denuded hilly landforms, the terrain has large undulations, well-developed joints, and many cracks. The irregular distribution of mud and black mudstone has a great impact on the stability of rock mass, leading to more geological disasters

[0003]Tunnel construction in the above-mentioned landforms not only increases the difficulty of tunnel construction and potential safety hazards, but also increases cost investment and delays the construction period. Support, often after the initial support construction is completed, the support layer often appears cracking, falling blocks, arch deformation, inverted arch bottom drum, landslide and roof fall and other disasters, resulting in a sharp increase in construction difficulty. How to effectively prevent and Reducing the impact of geological disasters on construction is an urgent problem to be solved

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