Construction method of large-section tunnel crossing fault fracture zone

Abstract

The invention discloses a construction method of a large-section tunnel crossing fault fracture zone. The construction tunnel cavern is divided into a tunnel upper cavern body, a tunnel lower cavern body and a tunnel bottom cavern body from top to bottom; the tunnel upper cavern body comprises a left pilot tunnel and a right pilot tunnel; the tunnel lower cavern body is divided into a left cavernbody, a left-middle cavern body, a right-middle cavern body and a right cavern body from left to right; practical construction comprises the following steps: (I) excavating the tunnel upper cavern body; (II) excavating the tunnel lower cavern body; (III) excavating the tunnel bottom. The method disclosed by the invention has the advantages of simple steps, reasonable design, convenience in construction and good using effect; only the upper half section of the tunnel is excavated by median septum excavation, thus the excavation section is reduced, and the vault stability is guaranteed; moreover, the left and right pilot tunnels have enough space and thus the construction is facilitated; meanwhile, a full-section support system and a mid-partition temporary support structure are both supported through lower bearing beams and are connected to form an overall support system with a stable structure, thus sinking of the primary support arching can be avoided while the stability of primary support is effectively guaranteed.

Description

technical field [0001] The invention belongs to the technical field of tunnel construction, and in particular relates to a construction method for a large-section tunnel crossing a fault fracture zone. Background technique [0002] With the increase of highway transportation volume and the development of infrastructure projects, single-hole, two-lane, multi-lane highway large-section tunnels are becoming more and more common. Compared with single-line small-section tunnel construction, large-section tunnel construction is more likely to cause large-scale subsidence of the vault during excavation. Especially in the construction process of large-section tunnels crossing fault fracture zones, the vault deformation rate is fast after excavation, the subsidence is too large in a short period of time, and the side walls and arches are twisted and deformed. collapse and other characteristics, in this case, if conventional construction methods and support systems are adopted, such ...

AI Technical Summary

Problems solved by technology

Especially in the construction process of large-section tunnels crossing fault fracture zones, the vault deformation rate is fast after excavation, the subsidence is too large in a short period of time, and the side walls and arches are twisted and deformed. collapse and other characteristics, in this case, if conventional construction methods and support systems are adopted, such as the step method, three-step method, double-side wall pilot method, CD method, CRD method, etc., the deformation can be controlled very well on the one hand, and on the other hand The construction process is complicated, and the complicated construction method leads to a long construction time and long-term exposure of the surrounding rock, which is likely to cause large-scale encroachment of the surrounding rock, spalling and falling of the shotcrete, and distortion of the steel frame, which further increases the risk of collapse, and the safety and quality cannot be guaranteed. At the same time, it also severely restricts the construction period

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