构皮滩水电站尾水隧洞特大断面软岩开挖支护

构皮滩水电站尾水隧洞软岩不良地质洞段占尾水隧洞全长的70%以上,确保软岩洞段的安全快速开挖是尾水隧洞施工的关键,尤其一次支护的强度对洞室稳定影响极大。为此,施工中根据软岩的地质特点及尾水隧洞开挖的断面尺寸,采取分层开挖和超前锚杆的施工方式和型钢拱架进行一次支护。根据监测结果,围岩变形很小,一次支护效果良好,表明构皮滩水电站尾水隧洞大断面软岩采取的开挖方式和一次支护方式是成功的。

Excavation Support for Soft Rock on Unusually-large-section of Tail Tunnel of Goupitan Hydropower Station

The length of section in soft rock of tail tunnel takes more than 70% of the whole one.The key of the tunnel construction,therefore,is safely and rapidly constructing in the section with bad geological conditions.The first support is especially important for stability.According to geological features of the soft rock and the size,the construction methods of stratified excavation and anchor pole in advance were taken,and structure steel frames were used for the first support.The monitoring results had made known that the deformation of adjoining rock was small,the effect of the first support was well.