高铁隧道穿越不同岩性接触带施工方法研究

随着我国高速铁路在西部地区的大力发展,铁路隧道经常需要穿越不同岩性接触带地层。隧道在穿越不同岩性接触带的施工过程中,易出现围岩塌方、变形过大、支护开裂等问题。以银西高铁贾塬隧道穿越不同岩性接触带为研究背景,采用FLAC^3D软件模拟隧道分别采用三台阶法,三台阶七步法,三台阶核心土法,三台阶临时仰拱法穿越红黏土与砂岩夹泥岩接触带,分析4种工况下围岩位移、围岩应力和支护应力的变化规律,并结合现场监测数据验证,比选出最优工法。研究结果表明:隧道穿越红黏土与砂岩夹泥岩接触带时,上下两种地层围岩位移相差较大;采用不同工法施工时,围岩应力和支护应力分布规律不同;采用三台阶临时仰拱法和三台阶七步法能够有效控制围岩位移;采用三台阶预留核心土法和三台阶七步法施工时支护受力更加均匀。

Study on Construction Method of Tunnel Passing Contact Zones of Different Lithology

With the development of high-speed railway tunnel in western China,tunnels often pass through contact zones of different lighology.There are many problems during the construction,such as surrounding rock collapse,excessive displacement and support cracking.Based on the Jiayu tunnel of the Yinxi high-speed railway passing through different lithologic contact zones,this paper uses FLAC3 D to simulate modes of tunnel passing through the contact zone between red clay and sandstone with mudstone by means of three-bench method,three-bench and seven-step method,three-bench core soil method and three-bench temporary invert method.By analyzing the variation of surrounding rock displacement,surrounding rock stress and support stress under four different working conditions,and combining with field monitoring data,the optimal method is selected.The results show that when the tunnel passes through the contact zone between red clay and sandstone with mudstone,the displacement of surrounding rock between the upper and lower strata is quite different.The distributions of surrounding rock stress and supporting stress are different in different construction methods.The displacement of the surrounding rock is effectively controlled by using three-bench temporary invert method or three-bench and seven-bench method.The support stress is more uniform either the three-bench reserved core soil method or the three-bench and seven-step method is used.