Unsymmetrical-pressure tunnel portal excavation protection structure and method for constructing same

Abstract

The invention discloses an unsymmetrical-pressure tunnel portal excavation protection structure and a method for constructing the same, and belongs to the field of tunnel engineering. The unsymmetrical-pressure tunnel portal excavation protection structure comprises a frame, pipe sheds, anchor ropes, antislip piles and side walls. The anchor ropes and the frame are anchored and connected with one another, so that slopes on the side surface of a tunnel can be supported; the side walls are arranged on shallowly buried sides of the tunnel; guide pipes penetrate the tops of the side walls to extend into a mountain, and holes can be drilled via the guide pipes; the pipe sheds penetrate the guide pipes, and the anchor ropes are nested in the pipe sheds; the antislip piles are arranged at the bottom of the frame, the bottoms of frame columns are connected with the tops of the antislip piles, and the anchor ropes penetrate the antislip piles to be anchored in stable regions of the mountain; spaces between the side walls and the mountain are backfilled with soil in a layered manner and are tamped; the insides of the pipe sheds and the anchor ropes are grouted in a time-sharing manner to reinforce the soil, the side walls and the antislip piles are connected with one another by the anchor ropes and the pipe sheds to form the integral structure, the integral structure is anchored in the stable regions of the mountain, and the tunnel is constructed in closed regions of the side walls, the antislip piles and the pipe sheds by means of underground excavation. The unsymmetrical-pressure tunnel portal excavation protection structure and the method have the advantages that protectors are formed before portals are excavated, the backfilled soil is beneficial to excavating the portals, unsymmetrical pressures can be reduced, the tunnel can be prevented from slipping, and unsymmetrical-pressure tunnel safety construction and operation can be guaranteed.

Description

technical field [0001] The invention specifically relates to an excavation protection structure for an opening of a biased tunnel, and belongs to the technical field of tunnel engineering. Background technique [0002] In recent years, the construction of highways and high-speed railways in my country has developed vigorously, and a large number of tunnel projects have been produced accordingly. Most highways and railways are generally routed along valleys, so shallow-buried bias tunnels account for a considerable proportion of these tunnel projects. Excavation of bias-pressure tunnel entrances has always been a major problem in the geotechnical engineering industry, especially in weak surrounding rock areas with complex terrain and geological environments. The stability is poor, the burial depth of the tunnel entrance section under bias pressure is extremely shallow, and the mountain is greatly disturbed during excavation, which is likely to cause problems such as tunnel si...

AI Technical Summary

Problems solved by technology

Although these methods are widely used in the excavation of eccentric tunnels, they do not fundamentally strengthen the unstable mountain and reduce the disturbance

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