软弱围岩大断面小净距隧道施工技术

摘要

Based on the practice in the large section and low net-distance tunnel of shallow and soft surrounding rock,the paper adopts the numeric simulation technique by combining with the field supervision,compares and analyzes the excavation design support scheme 1 of the double side drift method of the soft surrounding rock,the displacement of the surrounding rock in optimized and changed scheme 2,the features of the stress changes,and proves by the calculation results that the maximum change of the optimized scheme 2 and the design scheme 1 are within the regulation,and the maximum stress of the scheme 2 is a little larger than the one of the scheme 1,but lower than the compressive strength and tensile strength of post lining,and indicates the optimized excavation support scheme 2 is safe and feasible by considering the engineering practice comprehensively.%依托浅埋软弱围岩大断面小净距隧道工程实践,采用数值模拟技术结合现场监测,对比分析了软弱围岩双侧壁导坑法开挖设计支护方案1与优化变更方案2的围岩的位移、应力变化特征。计算结果显示：优化方案2与设计方案1围岩最大变形都在规范规定以内。方案2围岩最大的应力要略比方案1大,但远低于过衬砌的抗压强度和抗拉强度。综合考虑工程实践,优化开挖支护方案2是安全可行的。