Three-step arch beam type support construction method for tunnel

Abstract

The invention discloses a three-step arch beam type support construction method for a tunnel. The three-step arch beam type support construction method comprises the following steps that S1, an upper step is excavated; s2, the two sides of the middle step are excavated in a staggered mode, and middle step core soil is reserved; s3, lower step excavation is conducted, the two sides of a lower step are excavated in a staggered mode, and lower step core soil is reserved; s4, excavating reserved core soil of the middle step and the lower step; s5, after the excavation length of each cycle is 2-3 m, the inverted arch part is excavated, and the steel arch frame is closed in time; after three tunnel bottoms are excavated and support circulation is completed, a polyethylene slow-release energy dissipation layer of 10-20 cm is laid on the upper portion of a primary support, and an inverted arch is constructed; s7, after the tunnel excavation footage ranges from 25 m to 30 m, an edge and top arch polyethylene slow-release energy dissipation layer is laid, and edge and top arch secondary lining construction is conducted; and S8, the upper step, the middle step, the lower step and the inverted arch of the tunnel are constructed alternately according to the steps till tunnel excavation is completed.

Description

technical field [0001] The invention relates to the technical field of tunnel engineering, in particular to a three-step arch beam type support construction method used in a tunnel. Background technique [0002] my country ranks among the top in the world in terms of difficulty and scale in the construction of long-distance water diversion projects. Most of the water diversion projects built in high mountains and ridges use tunnel water delivery. Long-distance water diversion tunnels are the key control projects in the construction of water diversion projects. . Most of the long-distance water conveyance tunnels currently under construction and proposed in China have to pass through mountainous areas with complex geological tectonic backgrounds in the west, and face unfavorable factors such as harsh natural environment, high seismic intensity, and complex topographic and geological conditions. will greatly increase and face more complex scientific and technological problems....

AI Technical Summary

Problems solved by technology

[0005] (1) It is difficult for cement grout to enter the micro-cracks of expansive soft rock, and the traditional anchor support cannot achieve the ideal grouting reinforcement effect;

[0006] (2) Multiple primary support measures have complicated procedures, high cost and long construction period;

[0007] (3) Expansive soft rock deforms quickly and lasts for a long time, which often causes local crushing of the early spray layer and cracking of the secondary lining in the later stage, and the safety of the tunnel during operation cannot be guaranteed

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