Excavation and support methods for large-section tunnels crossing fault fracture zone

Abstract

The invention discloses an excavation and support method of large cross-section tunnel through fault fracture zone. The initial support structure of tunnel comprises a whole cross-section support system and the lattice girder and shotcrete support structure of the tunnel. A temporary support structure of middle-partition wall is arranged between a left pilot tunnel and a right pilot tunnel. The actual construction includes the steps: 1, excavation of the upper tunnel body; 2, the judgment of the initial support deformation of the tunnel arch wall and the construction of the replacement arch; 3, excavation of the lower tunnel body. The excavation and support method of large cross-section tunnel through the fault fracture zone has reasonable design, simple construction, and good use effect.Only the upper half section of the tunnel is excavated by the center diaphragm method, and the excavation cross-section is reduced so that the stability of the arch roof is ensured. The whole cross-section support system and the temporary support structure of middle-partition wall are supported by the underpass beam and joined together to form a stable monolithic support system, which can avoid the sinking of the supporting arch and ensure the stability of the initial support effectively. Besides, the construction of replacement arch is conducted on only half cross-section of the tunnel and the cost can be saved, and the construction safety can be ensured.

Description

technical field [0001] The invention belongs to the technical field of tunnel construction, and in particular relates to an excavation and support 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 ado...

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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