Construction method for rapid expanding excavation conversion during sudden change of large-span section of tunnel section

Abstract

The invention belongs to the field of tunnel engineering, and particularly relates to a construction method for rapid expanding excavation conversion during a sudden change of a large-span section of a tunnel section. The method includes the steps that when the tunnel section enters into a transition section of the abrupt change large-span section, a longitudinal advance pilot tunnel and a longitudinal follow-up pilot tunnel are excavated in sequence, and expanding excavation is conducted towards the arch part of the abrupt change large-span section while the follow-up pilot tunnel is excavated; then 90-degree straight turning expanding excavation is conducted in the direction of a side wall, reserved steps are excavated, an arch frame is annularly lengthened within a longitudinal length range, and arch feet are erected on the reserved steps of a longitudinal side wall; and then a reserved step is excavated in the longitudinal direction of a main tunnel, and primary support of the upper middle portion of the transition section is safely and rapidly completed. Therefore, construction safety is guaranteed, meanwhile, operation space is provided for follow-up large-span section right side upper pilot tunnel construction, and the defects that when a variable section construction method is converted, equipment is difficult to unfold, the construction speed is low, and the safety risk is high are overcome.

Description

technical field [0001] The invention belongs to the field of tunnel engineering, and relates to a construction method for rapid expansion and excavation conversion when the tunnel section suddenly changes to a large-span section, and more specifically, relates to an excavation and support for lateral rapid expansion and excavation conversion when the tunnel section suddenly changes to a large-span section 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. Qiaopingshan Tunnel is a newly added tunnel for the station adjustment of Chongqing East Station on the East Ring Road of Chongqing Railway Hub. The section is A, the long-span section B, and the section changes suddenly to the side of the lead-ou...

AI Technical Summary

Problems solved by technology

[0003] The transition process of different excavation methods at the sudden change 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, and the safety risk is high. The safe and fast transition from the step method to the large-span three steps Temporary inverted arch construction method, there is no better method

Images