Composite retaining structure suitable for deep tunnel of clastic schist layer and construction method thereof

Abstract

The invention discloses a composite retaining structure suitable for a deep tunnel of a clastic schist layer and a construction method thereof. The composite retaining structure comprises a forepoling, a tunnel steel arch and a shotcreting mesh combined support, wherein the forepoling comprises a plurality of tunnel face fiber anchor rods which are perpendicularly driven on a tunnel face, multiplesections of advanced small guide pipe supports and a grouting reinforcement area, the plurality of tunnel face fiber anchor rods completely cover the tunnel face, each section of the advanced small guide pipe support is composed of a plurality of advanced small guide pipes, the overlapping length of each section of the advanced small guide pipe support is not less than 1 m or 1 / 4 L of the guide pipes in the tunnel excavation direction, each section of the advanced small guide pipe support, i.e. the plurality of advanced small guide pipes, is driven on the arch of the tunnel face within the range of 120 degrees, and the grouting reinforcement area is formed in a way that the tunnel face fiber anchor rods and tunnel face surrounding rocks in an area in which the advanced small guide pipes are arranged are grouted. According to the composite retaining structure, the stable tunnel face is effectively guaranteed, the collapse of an excavation face is prevented, the deformation of the support is effectively controlled, the safety in construction is guaranteed, and the construction efficiency is improved.

Description

technical field [0001] The invention relates to the field of tunnel support structures, in particular to a combined support structure suitable for deep-buried tunnels in clastic schist formations and a construction method thereof. Background technique [0002] The surrounding rock of the clastic schist formation is broken, with low cohesion and poor self-stabilization ability. If the support is improper after excavation, it is easy to cause collapse and slide of the excavation face and face, excessive support deformation and support failure. The structural instability seriously affects the construction quality and operation safety of the tunnel. [0003] At present, deep-buried tunnels in clastic schist still adopt the traditional "advance support + steel arch frame + shotcrete + bolt" primary support form, and there is no specific calculation method for determining support parameters. It is often impossible to guarantee the stability of the excavation face and the tunnel f...

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Problems solved by technology

[0002] The surrounding rock of the clastic schist formation is broken, with low cohesion and poor self-stabilization ability. If the support is improper after excavation, it is easy to cause collapse and slide of the excavation face and face, excessive support deformation and support failure. Structural instability seriously affects the construction quality and operational safety of the tunnel

[0003] At present, deep-buried tunnels in clastic schist still adopt the traditional "advance support + steel arch frame + shotcrete + bolt" primary support form, and there is no specific calculation method for determining support parameters. It is often impossible to guarantee the stability of the excavation face and the tunnel face, and phenomena such as landslides and excessive support deformation often occur, threatening construction safety and greatly reducing construction efficiency

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