Large-span double multi-arch tunnel excavation method in urban complex environment

Abstract

The invention discloses a large-span double multi-arch tunnel excavation method in the urban complex environment, which comprises the steps of: excavating three pilot tunnels, i.e., excavating the three pilot tunnels in a mode of firstly excavating a middle pilot tunnel and following up excavation of left and right pilot tunnels by opening the step pitches; after excavation of the third pilot tunnels is completed, pouring a left side wall of the left pilot tunnel, a right side wall of the right pilot tunnel and a middle partition wall of the middle pilot tunnel; and after the left side wall, the right side wall and the middle partition wall are poured, excavating a main tunnel of the double multi-arch tunnel in the mode that an upper step is firstly constructed by a CD construction method in a penetrating mode and then a middle step and a lower step are constructed, wherein supporting points of primary supporting are all located on the left side wall, the right side wall and the middle partition wall when the main tunnel is excavated. The construction method of firstly penetrating the upper step of the main tunnel, carrying out the primary supporting at the same time to form a multi-arch cover tunnel structure and then excavating the middle step and the lower step is reasonable, and construction safety is guaranteed.

Description

technical field [0001] The invention belongs to the technical field of excavation of underground double-arch tunnels, and in particular relates to an excavation method for large-span double-arch tunnels in complex urban environments. Background technique [0002] Under the complex urban environment, the long-span double-arch tunnel under the main road of the city has a small rise-span ratio and a relatively flat cross-section. The soil body is particularly easy to be shortened or opened along the joint direction, and the damage area is large. Usually, it is difficult to form a load-bearing arch. . Therefore, the excavation method of three pilot tunnels is adopted to increase the bearing capacity of the arch in the main tunnel, so as to meet the safety and stability of the excavation of the main tunnel. According to the current construction technology status in China, there are mainly two construction methods for long-span double-arch tunnels: the three-pilot method and the ...

AI Technical Summary

Problems solved by technology

[0003] However, in the common three-pilot large-span double-arch tunnel, there are few analyzes on the longitudinal excavation spacing of the main tunnel, which cannot take into account the problems of poor geological conditions, large spans, and high safety requirements on urban arterial roads.

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