An Excavation Method in the Vault Direction for Expansion of Existing Tunnel

Abstract

The invention discloses an excavation method in the direction of the vault when the existing tunnel is expanded. First, the excavation surface is divided into two parts, left and right, and the left half is excavated first, and a temporary partition wall and a steel arch are constructed. The left half is excavated 1 to 2 times the diameter of the single hole, and then the right half is excavated, and a steel arch is constructed, and the secondary lining is applied after the surrounding rock becomes stable, and so on, until the construction is completed. This excavation method can reduce the degree of disturbance to the surrounding rock during the construction of the roof for the poor working conditions of the surrounding rock. The excavation method also discloses an assembleable cylindrical temporary support, which is used in conjunction with a temporary partition wall after excavation to form a temporary closed ring and maintain the stability of surrounding rock.

Description

technical field [0001] The invention relates to an excavation method in the vault direction when an existing tunnel is expanded, and belongs to the technical field of tunnel construction methods. Background technique [0002] With the development of our country's society and the increasing demand for transportation, the tunnels and underground civil air defense projects built in the early days of the founding of the People's Republic of China can no longer meet the current use requirements. The lining of tunnels and underground civil air defense projects built in the early days of the People's Republic of China is mostly plain concrete. When expanding such existing underground caverns and tunnels, the lining and surrounding rock will have great safety hazards. At present, the excavation and support technology in our country is relatively mature, but there are few records on how to ensure the stability of the surrounding rock at the top of the roof section after the plain con...

AI Technical Summary

Problems solved by technology

The traditional method uses blasting to excavate gradually in the expansion of the arch, but because the grade of the surrounding rock is poor, and the tunnel has no initial support, this will greatly affect the stability of the surrounding rock of the arch that has not yet been excavated. Influence, the number of times of disturbance to the surrounding rock is large, and the degree of disturbance is relatively large. When the rock and soil mass in the arch of the tunnel is expanded, the phenomenon of instability and collapse will occur

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