A construction method of shallow buried long-span tunnel suitable for upper soft and lower hard composite stratum

Abstract

The invention discloses a shallow-buried large-span tunnel construction method suitable for a composite stratum with the soft upper portion and the hard lower portion and belongs to the field of tunnel engineering. In the construction process, the lower portions of big arch feet of a tunnel are each provided with a linear section, the height between an arch cover and a rock mass on the lower portion is increased, and thus damage of splashing rock in the blasting process to an arch body is avoided; and meanwhile, through cooperation of an elastic cushion layer, the influence of blasting vibration to the arch body can be reduced to the maximum limit. In addition, spaces are provided for pouring of concrete blocks through the design of the linear sections, and the horizontal load formed by the covering soil load can be effectively shared through cooperation of the concrete blocks and anchor rods, so that the parts, at the linear sections, of the arch body are stable in structure; and meanwhile the water leakage problem of the arch feet is solved through pouring of the concrete blocks. The defects of construction methods such as the double-side-wall pilot tunnel method and the arch cover method are avoided effectively, and a new idea is provided for shallow-buried tunnel construction under the geological condition of the composite stratum with the soft upper portion and the hard lower portion.

Description

technical field [0001] The invention belongs to the field of tunnel engineering, and in particular relates to a shallow-buried large-span tunnel construction method suitable for upper-soft and lower-hard composite formations. Background technique [0002] At present, the excavation methods of shallow-buried long-span tunnels mainly include the double-side-wall pilot-pit method and the double-lined arch-cover method. The double-side-wall pilot pit method is also called the eye construction method, that is, the excavation section is divided into blocks, and each block is independently closed to form a ring after excavation, which can better control deformation and ensure construction safety. However, due to many processes, the construction period long. In the upper soft and lower hard formations, especially in the lower hard formations (medium weathered and slightly weathered rocks), there are limitations in the application of the double-side-wall pilot pit method in blasting...

AI Technical Summary

Problems solved by technology

Later, on this basis, some structural forms such as compound lining (primary support + secondary lining) and superimposed arches were developed and innovated on the arch. The construction joints left in the upper part of the tunnel lead to serious water leakage at the foot of the arch; second, due to the limited space in the upper arch part, the blasting of the rock mass in the lower part of the tunnel may cause impact damage to the vault structure

Images