Construction method of double-side wall guide pit composite stepped large-section tunnel excavation support

Abstract

The invention provides a construction method of a double-side wall guide pit composite stepped large-section tunnel excavation support, which comprises the following steps: when a guide pit is excavated, the cross section of the guide pit is partially overlapped with the tunnel section along the longitudinal direction of the tunnel, a side wall is arranged in the guide pit, and the side wall is attached to the outer contour of the tunnel section; before the tunnel main hole is excavated, the tunnel slag back pressure backfill is carried out the guide pit and the tunnel core part, and the corresponding guide pit support structure is removed synchronously according to the excavation progress of the main hole during the excavation process of the main hole. The construction method has the advantages that the lateral deformation and bottom bulge deformation of the tunnel are prevented, the lining quality at the later stage of the tunnel is ensured, and the safety risk in large span and large section tunnel construction can be effectively controlled.

Description

technical field [0001] The invention relates to the technical field of tunnel construction, in particular to a construction method for excavating and supporting double-side-wall composite stepped large-section tunnels. Background technique [0002] In tunnel construction, the CRD method and double-side-wall pilot-pit method are often used for tunnel construction in unfavorable geological sections such as high ground stress and weak and broken surrounding rock. As far as the weak stratum is concerned, there are many limitations in the reasonable form of the primary support structure, the construction efficiency of the excavation process division, and the risk control of the primary support removal and replacement, which need to be further improved and perfected. [0003] In addition, for mountain tunnels with large buried depths in weak surrounding rocks such as fault fracture zones, especially in the case of large horizontal stresses, how to prevent lateral deformation, espe...

AI Technical Summary

Problems solved by technology

[0002] In tunnel construction, the CRD method and the double-side-wall pilot-pit method are often used for tunnel construction in unfavorable geological sections such as high ground stress and weak and broken surrounding rock. For weak strata, there are many limitations in the rational form of the primary support structure, the construction efficiency of excavation process division, and the risk control of primary support removal and replacement, which need to be further improved and perfected.

[0003] In addition, for mountain tunnels buried deep in weak surrounding rocks such as fault fracture zones, especially in the case of large horizontal stresses, how to prevent lateral deformation, especially bottom uplift deformation, etc., the current construction methods are all There is a lack of clear and effective countermeasures, and the construction experience that can be used for reference is also very limited. The corresponding construction technical measures are basically in a blank state. and technical measures are extremely difficult

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