Method for excavating micro benches of large-section loess tunnel, and bench structure of large-section loess tunnel

Abstract

The invention discloses a method for excavating micro benches of a large-section loess tunnel. The method comprises the following steps of excavating a ramp; excavating an upper bench located at the upper layer, and performing reserving at the middle part of the upper bench to form an upper core loess layer; excavating a middle bench, and trimming the upper core loess layer to form a middle core loess layer located in the bench surface of the middle bench; excavating a lower bench; and excavating an inverted arch. According to the method disclosed by the invention, the tunnel is vertically divided into three layers of benches, a core loess layer is reserved by the upper bench to form an earth column supporting tunnel face, so that the situation that the tunnel face is destabilized is avoided; and besides, the arranged inclined ramp is used in the whole construction operation stage of the upper bench, the middle bench and the lower bench, so that the large-scale machines can effectivelyoperate in the ramp; and the ramp is used in the whole construction stage of the benches, so that the spacing between the benches is reduced.

Description

technical field

[0001] The invention relates to the technical field of tunnel excavation, in particular to a micro-step excavation method for a large-section loess tunnel and a step structure thereof. Background technique

[0002] The scale of infrastructure construction is unprecedentedly high, the traffic road network continues to expand and improve, and long tunnels for railways and highways will continue to emerge in the central and western regions. There is a wide range of loess strata distributed in Northwest my country, and the three-step and seven-step method has been widely used in the excavation of loess tunnels. However, the micro-step excavation method for large-section loess tunnels has not been reported yet.

[0003] In view of the fact that the large-section loess tunnel adopts the three-stage seven-step method to reserve the core soil through the upper, middle, and lower steps, and divides the tunnel into seven parts, but due to the existence of layered step...

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