Double-layer primary support structure of weak surrounding rock tunnel and construction method thereof

Abstract

The invention discloses a double-layer primary support structure of a weak surrounding rock tunnel and a construction method thereof and belongs to the technical field of tunnel construction. The double-layer primary support structure of the weak surrounding rock tunnel comprises a single-layer mesh reinforcement. The outside arc face of the single-layer mesh reinforcement is provided with anchorholes. Anchor rods are inserted into the anchor holes. According to the double-layer primary support structure of the weak surrounding rock tunnel, by means of mutual cooperation of the designed anchor rods, connection holes, bearings, rotating shafts, threaded rods, threaded cylinders, fins, pin shafts, limiting holes, an outer layer interrupted type arch frame, buffering devices, an advanced flexible net-structure protective cover, a buffering air cushion layer and other structures, by changing the position relationship between the fins and the anchor rods, the stress area of the anchor rodscan be effectively increased, and then the anchorage effect of the anchor rods on the overall structure can be effectively improved; and meanwhile, the adopted flexible connection relationship can effectively weaken the degree of the problems that deformation time is long, the deformation amount is large, the deformation speed is rapid, the time of duration is long, a large area of surrounding rock extrudes and invades into a limitation bound, and the support cracks or damages severely.

Description

technical field [0001] The invention belongs to the technical field of tunnel construction, and in particular relates to a double-layer primary support structure for tunnels with weak surrounding rocks and a construction method thereof. Background technique [0002] With the construction of large-scale, modern, and high-standard urban roads and transportation projects in my country, the number and construction scale of tunnel projects continue to expand, and weak surrounding rock strata will inevitably be encountered. Weak surrounding rock is descriptively defined as a rock mass with loose structure, poor cementation, broken, swelling, weathering, low strength, large pores, significantly affected by structural plane cutting and weathering, or containing a large amount of expansive clay minerals; its index It is defined as a rock formation with a uniaxial compressive strength of 0.5-25 MPa and σc / (γH)<2, where σc is the uniaxial saturated compressive strength, γ is the roc...

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Problems solved by technology

[0004] The purpose of the present invention is: in order to solve because the internal geological structure of weak surrounding rock is relatively soft, and its structure of the bolt used is relatively simple, it is difficult to achieve a relatively stable fixing effect on the steel mesh sheet, and the stability of the steel mesh sheet Poor, and due to the creep characteristics of the weak surrounding rock, it is very easy for the initial support to deform for a long time, the deformation amount is large, the deformation speed is fast, and the duration is very long. It is very serious. Preventing the further deformation and convergence of the surrounding rock at this stage will inevitably require the initial support structure to have high rigidity and high strength, resulting in a high cost of the support structure. Therefore, it must be strong and flexible to adapt to this deformation convergence problem. A proposed double-layer primary support structure and construction method for tunnels with weak surrounding rock

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