Construction method of the middle wall of the upper step of the tunnel crossing the stratum fracture zone

Abstract

The invention discloses a method of constructing a center division of an upper bench of a tunnel crossing a stratum fracture zone. Upper bench excavation is performed on a construction tunnel from rear to front so as to obtain an excavated tunnel upper hole; a center division temporary support structure is arranged in the tunnel upper hole; a tunnel primary support structure of the tunnel upper hole includes an arch wall anchor net spray support structure and an arch wall rigid support system. The upper bench excavation includes I, excavating a left guide hole, and carrying out primary supporting; II, excavating a right guide hole and carrying out primary supporting. The method has simple steps, reasonable design, good construction simplicity and good service effect; a tunnel upper half section is excavated by means of a center division method, excavation section is narrowed, and stability of an arch top is guaranteed; both the arch wall rigid support system and the center division temporary support structure are supported via a lower bearing beam and are connected into an integrated stable-structure support system; settling of a primary support arch frame in the upper hole can beavoided, and stability of primary supporting can be 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 middle partition in a tunnel passing through a stratum 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 a...

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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