Excavation construction method for unsymmetrical small-space tunnel

Abstract

The invention relates to a construction method for an unsymmetrical big-span and small-span subway tunnel, namely an excavation construction method for an unsymmetrical small-space tunnel. The excavation construction method comprises the following steps: firstly, excavating a small-span tunnel; putting an anchor rod in a clamped rock between a big-span tunnel and the small-span tunnel before the primary support of the small-span tunnel is manufactured, wherein the anchor rod has the functions of grouting and oppositely pulling; then manufacturing the primary support of the small-span tunnel; welding one end of the anchor rod with the primary support of the small-span tunnel; excavating the big-span tunnel by steps after the secondary lining of the small-span tunnel is manufactured; firstly excavating one side close to the small-span tunnel; processing and welding the other end of the anchor rod to the primary support of the big-span tunnel to form the oppositely pulling anchor rod; excavating the big-span tunnel by steps; and manufacturing secondary tunnel linings. In the excavation construction method, the clamped rock stability for excavating the small-span tunnel and the space effect of surrounding rock stress variation are considered, the oppositely pulling grouting anchor rod is used for reinforcing the clamped rock; the excavation sequence of firstly excavating the small-span tunnel and then excavating the big-span tunnel is cooperated; and the effects on stabilizing the clamped rock and controlling the support structure of the tunnel and ground sedimentation are obvious.

Description

technical field [0001] The invention relates to a tunnel excavation construction method applied in the field of urban subway engineering, in particular to an asymmetric small-spacing tunnel excavation construction method. Background technique [0002] Affected by terrain, line selection, etc., urban subway tunnels have frequent and increasingly complex cross-section forms, and there are more and more asymmetric tunnel sections with small spacing. Small spacing tunnels composed of wire tunnels. The main problems in the excavation of asymmetric small-spacing tunnels are the stability of the interlayer rock during the excavation process and the differential settlement of the ground caused by uneven force on the tunnel structure. In addition, since the buildings and pipelines around urban subway tunnels are complex and sensitive to differential settlement, it is necessary to take reasonable interlayer rock and structural reinforcement measures and choose a reasonable excavation...

AI Technical Summary

Problems solved by technology

Under the condition of grouting, the integrity of the interlayer rock can be increased, but it has a limited effect on the integrity of the bias pressure in the excavation of asymmetrical tunnel sections, and cannot improve the integrity of the cavern structure, so it has the effect of reducing the differential settlement of the tunnel. limited

In the excavation sequence of tunnels with asymmetrical cross-sections, the later excavation of small-section tunnels has a greater impact on the stress distribution of the surrounding rock of large-section tunnels excavated earlier, resulting in a large rotation angle of the principal stress, which is not conducive to the structural stress. Compared with excavating the tunnel first, the stagger distance is longer, which is not conducive to shortening the construction period

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