Construction method of super-long expansion head anchor cable of large deformation tunnel with high ground stress and weak surrounding rock

Abstract

The invention discloses a construction method of a super-long expansion head anchor cable of a large deformation tunnel with high ground stress and weak surrounding rock, and belongs to the field of tunnel construction. The construction method includes the following steps that drilling is performed; anchor cable braiding is performed, specifically, the anchor cable is formed by braiding steel strands, and the cross-sectional dimension of an anchor cable expansion head is larger than the cross-sectional dimension of other parts of the anchor cable; the anchor cable is installed, specifically, the anchor cable is disposed at the drilling center during installation; anchoring section grouting is performed; tensioning and locking are performed; tensioning section grouting is performed; and anchor sealing is performed. The construction method adopts the stress super-long expansion head anchor cable, the construction is convenient and fast, since the release of the high ground stress is a long-term process, the pre-stress super-long expansion head anchor cable can well reinforce the continuous deformation of the surrounding rock, and the number of times of operation of initial support arch replacement and second lining rework and replacement is greatly reduced; and meanwhile, the huge number of manpower and material resources required by a conventional support method can be avoided,and the progress of project is improved.

Description

Technical field [0001] The invention relates to the field of tunnel construction, in particular, is a method for the construction of an ultra-long expansion head anchor cable for a large deformation tunnel with high ground stress and weak surrounding rock. The method is suitable for soft surrounding rock tunnels, karst tunnels, deep foundation pit projects, and high slope projects. Wait. Background technique [0002] High in-situ stress has a significant impact on geotechnical engineering, especially for underground engineering with large buried depth and weak surrounding rock, such as railway tunnels, highway tunnels, and deep mining tunnels. With the continuous development of my country's railway and highway construction, tunnel engineering has developed in the direction of growth and deep burial. Therefore, in recent years, there have been continuous emergence of long and large tunnel projects in weak surrounding rocks that pass through high ground stress areas and have harsh...

AI Technical Summary

Problems solved by technology

[0003] After excavation and support, the large-deformation tunnel with weak surrounding rock and high ground stress has strong extrusion and deformation of the surrounding rock, resulting in large-scale damage to the primary support, cracking of shotcrete, twisted and broken steel frames, and encroachment of side walls. The release in the surrounding rock tunnel is often a long-term and slow process, and it will also cause the secondary lining that has been prepared in the early stage to crack continuously in the later stage, requiring rework and renovation

Therefore, problems such as broken surrounding rock, large ground stress, and long release period lead to large convergence of tunnel construction deformation, frequent process changes and program changes, discontinuous construction and production, and low work efficiency, which seriously plague the construction schedule and construction safety.

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