Weak surrounding rock auxiliary gallery small pilot tunnel crossing main tunnel roof brushing construction method

Abstract

The invention discloses a weak surrounding rock auxiliary gallery small pilot tunnel crossing main tunnel roof brushing construction method. The method comprises the following steps: (1) preparing for construction; (2) constructing an advance support of the small pilot tunnel; (3) excavating the small pilot tunnel in two steps after the advance support of the small pilot tunnel is finished; (4) performing combined support by using a steel frame, a system anchor rod, a reinforcement mesh and concrete after the excavation of the small pilot tunnel is finished; (5) timely constructing an upper primary support of the main tunnel when the small pilot tunnel is constructed to an arch springing outer side line on the other side of the main tunnel; (6) performing excavation support on the middle part and the lower part of the main tunnel. The method has the beneficial effects that the safety of an auxiliary gallery and fast entry into the main tunnel are guaranteed, the risk of high probability of collapse on the top of the tunnel during intersection construction at a weak surrounding rock geological section is reduced and avoided, the temporary support cost is saved and the construction progress is quickened.

Description

technical field [0001] The invention relates to the field of tunnel construction, in particular to a construction method for raising the roof of a small pilot tunnel crossing a main tunnel with an auxiliary tunnel with weak surrounding rocks. Background technique [0002] During tunnel construction, it is common to encounter tunnels with a contract section length greater than 5km. In order to increase the working face, speed up the tunnel construction progress, and improve the drainage and ventilation conditions during tunnel construction, auxiliary tunnels (inclined shafts) are set up. Compared with other sections of the tunnel, the intersection between the auxiliary tunnel and the main tunnel has a relatively weak construction safety link due to its larger cross-sectional space, and the intersection is mostly located in a broken zone with poor diagenesis, serious faults and geological structures. Weak surrounding rock geological section with low surrounding rock strength. ...

AI Technical Summary

Problems solved by technology

[0004] Aiming at the problem that the conventional bottom-up roofing method in the above-mentioned related technologies is not suitable for the roofing of the main tunnel under the condition of weak surrounding rock, the present invention proposes a construction method for the roofing of the main tunnel with the auxiliary tunnel and small pilot tunnel crossing the main tunnel under the condition of weak surrounding rock , can avoid the risk of the tunnel top collapsing easily when constructing intersections in weak surrounding rock geological sections, and does not require a large number of temporary supports, reducing costs

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