Construction method for excavating upper drift heading and lower drift heading in two side walls of ultra-large subsurface tunnel

Abstract

The invention provides a construction method for excavating an upper drift heading and a lower drift heading in the two side walls of an ultra-large subsurface tunnel and belongs to the technical field of construction engineering. The method comprises the steps of drilling and blasting scheme design; construction requirements meeting of drilling and blasting design; blasting parameter selection; surveying and setting out; excavation of the upper pilot tunnel portion and the lower pilot tunnel portion of the two side walls; removal of reserved rock beam portions; excavation of an annular core soil portion of an arch portion; and excavation of core soil middle-upper steps, middle-lower steps and lower steps. Compared with a traditional two-side-wall drift heading method, according to the method, the way of excavating the upper drift heading and the lower drift heading at the same time is adopted, and the characteristics of the large-section tunnel can be fully utilized; a working face which can be excavated is increased; tunnel excavation conducted at the early stage is accelerated; and the construction period is effectively shortened. According to the method, reserved rock beams are utilized, so that horizontal support strength and global stability are effectively enhanced; horizontal convergence deformation and arch top settlement of the tunnel are decreased; and safety of buildings on the upper portion of the tunnel is guaranteed. According to the construction method, after the high side walls are constructed by means of the bottom of a lower pilot tunnel of the tunnel, backfilling is conducted, the height of a second lining construction section of the tunnel is reduced, and the construction problem of an ultra-large-section formwork trolley is solved.

Description

technical field [0001] The invention relates to the technical field of construction engineering, in particular to a construction method for excavating upper and lower guide pits on double side walls of super-large underground excavation tunnels. Background technique [0002] Generally, with the continuous acceleration of the urbanization process in our country, the urban population is growing rapidly and the traffic pressure is increasing day by day. The use of underground space and the development of urban rail transit such as subways are of great significance to alleviating the pressure of urban public transportation and promoting the healthy development of urban economy and society. important role. In order to meet the needs of the rapid development of transportation, various super-large-section tunnel projects continue to emerge. How to ensure the safety of excavation and construction of super-large-section tunnels is still a difficult problem in domestic construction. ...

AI Technical Summary

Problems solved by technology

In recent years, for subway tunnel projects such as subways and rail transit, the tunnel sections of underground excavated stations in these projects are all 400m 2 The shallow-buried ultra-large-section tunnels above, some of which have a maximum cross-sectional area of ​​up to 760m 2 , due to the complex construction environment and great risk

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