Construction method for transverse expanding excavation conversion when tunnel section suddenly changes to large-span section

Abstract

The invention belongs to the field of tunnel engineering, and particularly relates to a construction method for transverse expanding excavation conversion when a tunnel section suddenly changes to a large-span section. According to the construction method, when the tunnel section enters the transition section of the suddenly-changed large-span section, firstly a preceding pilot tunnel is excavated, and then excavation expands towards the arch part of the suddenly-changed large-span section while excavating a following pilot tunnel; then 90-degree straight turning pilot tunnel expanding excavation is conducted in the side wall direction, during expanding excavation, a portal support is added to serve as temporary protection, and a portal cross beam is installed outside the large-span section contour line in the line direction; and after excavation is conducted to the position of a side wall arch foot of the large-span section, an annular arch frame of the large-span section is erected on the lower side of a portal cross beam at a time. According to the construction method, the portal support is large in operation space, high in safety and convenient to construct, meanwhile, the portal cross beam is arranged on the outer side of a main tunnel primary support arch frame, extension or erection of the main tunnel annular arch frame is not affected, the portal cross beam and upright end wall portal vertical supports at the junction of the two sections can serve as permanent primary supports, and the dismantling workload of the temporary portal is reduced.

Description

technical field [0001] The invention belongs to the field of tunnel engineering, and more specifically relates to a construction method for lateral expansion and excavation conversion when the tunnel section suddenly changes to a large-span section, and more specifically relates to an excavation for lateral expansion and excavation conversion when the tunnel section suddenly changes to a large-span section , Support construction method. Background technique [0002] In recent years, my country's railways have fully implemented the new development concept and paid more attention to the intensive use of underground space. New breakthroughs have been made in the construction technology of large-section tunnels and underground space engineering, and the design of variable diameter sections in large-section tunnels has gradually increased. Qiaopingshan Tunnel is a newly added tunnel for the station adjustment of Chongqing East Station on the East Ring Road of Chongqing Railway Hu...

AI Technical Summary

Problems solved by technology

[0003] The transition process of different excavation methods at the abrupt cross section is complicated, and the working space is narrow, which limits the difficulty of equipment construction. The disorder of excavation and support can easily lead to collapse, high safety risk, and there is no more mature method.

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