浅埋偏压小间距大跨隧道开挖工法的数值分析

摘要

软弱破碎岩土条件下合理确定浅埋偏压小间距大跨隧道开挖方法是隧道工程界目前一个亟待解决的难题.采用 FLAC3D对软弱围岩条件下大跨度浅埋偏压小间距隧道不同开挖工法的动态施工进行了数值模拟,得出了隧道开挖支护施工过程中围岩与支护体系的位移变形及应力扩展的发展规律.数值结果表明:隧道开挖支护过程中,仰拱处存在隆起应力,中间岩柱和深埋隧道右侧出现应力集中,二次衬砌顺承较大残余应力.研究成果有利于提高隧道的结构设计和施工水平,达到设计和施工更为经济、安全、合理的目标.%The problem that large-span,shallow embedded,small interval and bias tunnel of the most reasonable excavation in the soft wall rock is urgent to be settled.The numerical simulations of construction methods by FLAC3D,which was studied for large-span,shallow embedded and side stress tunnel with small interval of the soft wall rock is made in this paper,show the development discipline of displacement deformation and stress propagation for the surrounding rocks and support system during tun-nel excavation and support.The result show that when the twin tunnel is excavated and supported,uplift stress existed in tunnel invert,various stress has stress concentrate phenomenon in the surrounding rock between two tunnels and the left area of the deeper tunnel and the second lining bearing a large residual stress.The research results of this paper will do benefit to improve the design of structure and the level of constructing for large-span,shallow embedded,small interval and bias tunnel,and will make it more economical,more safe and more reasonable.