Excavation and supporting method for large-span underground cavern horizontal and oblique crossing four-fork

Abstract

The invention relates to an excavation and supporting method for a large-span underground cavern horizontal and oblique crossing four-fork and belongs to the field of underground engineering construction. According to the excavation and supporting method, a main cavern is excavated and supported firstly, after openings of branch caverns are locked, excavation and supporting are conducted at intervals according to the excavation sequence of the farthest branch cavern, the closest branch cavern and the middle branch cavern, excavation is closely followed by supporting, smooth blasting is adoptedduring excavation of a first top arch layer, and smooth blasting is adopted during reserving of a protecting layer on a bottom plate. The forming quality of an excavation and supporting technology isgood, the forming quality of cavern openings is good, overbreak and underbreak are effectively controlled, after blasting excavation, a tunnel face is closely followed by shotcrete-bolt supporting, construction safety is guaranteed, and overbreak-underbreak and a surrounding rock blasting loose circle can be effectively controlled; and safety accidents such as rock mass instability, shattering, loosening and collapse are reduced, the construction safety is improved, and economic benefits are increased.

Description

technical field [0001] The invention belongs to the field of underground engineering construction, and in particular relates to an excavation and support method for horizontal and oblique crossings of large-span underground caverns. Background technique [0002] With the development of underground space in our country, in the construction of water conservancy and hydropower, highways, ports and other underground projects, caverns are deeply buried, fork structures are becoming more and more common, and large-span horizontal and oblique intersections appear. Large burial depth, high ground stress, and long-span horizontal and oblique crossings have a large structural span, thin rock pillars are not easy to form, oblique crossings are wide and high, and some horizontal and oblique crossings have a width of more than 30 meters and a height of 18 meters For example, the tailwater branch tunnel of the Lianghekou hydropower station in Sichuan Yalong River and the four forks of the...

AI Technical Summary

Problems solved by technology

Large burial depth, high ground stress, and long-span horizontal and oblique crossings have a large structural span, thin rock pillars are not easy to form, oblique crossings are wide and high, and some horizontal and oblique crossings have a width of more than 30 meters and a height of 18 meters For example, the tailwater branch tunnel of the Lianghekou hydropower station in Sichuan Yalong River and the four forks of the tailwater tunnel. Scientifically designed support parameters, excavation and support construction methods, excavation and support at the fork may cause safety accidents such as rock mass instability, shattering, loosening, and landslides. There are large safety hazards that affect construction progress and economic benefits

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