陡倾岩层双洞四线暗挖车站结构设计研究

Research on the Structure Design for Four-tracked-double Station Tunnel in Steep Dip Stratum

研究目的:重庆轨道交通环线涂山站为陡倾岩层中双洞四线大跨暗挖车站,单洞开挖跨度为21.6 m,双洞净距19.7 m,所处岩层中斜层理和交错层理较发育,贯通性好,层面结合处岩体破碎,结合较差。本文采用Unwedge软件进行地下洞室开挖稳定性定性分析,并采用MIDAS/GTS进行三维施工过程模拟,以研究隧道合理支护参数和施工步序。研究结论:(1)根据分析结果,建议左、右洞一次拆撑长度分别不超过6 m和9 m;(2)在结构面顺层滑动的迎压侧墙及拱顶处增设中空锚杆大角度穿过结构面注浆加固;(3)施工过程中应加强偏压和迎压侧墙背部的围岩压力监测;(4)支护设计和结构计算应充分考虑偏压的不利影响;(5)本研究成果对于陡倾岩层中类似暗挖隧道的设计施工有一定的参考价值和借鉴意义。

Research purposes： Tushan station of Chongqing urban rail transit loop line is a four - tracked - double station tunnel with single hole excavation span of 21.6 m and double hole interval of 19.7 m in inclined stratum. The rock stratum in station range has a mature oblique bedding and cross bedding with good connectivity. The both sides of level junction are a rock broken zone with poor associativity. To study the support parameters and construction sequence of the station tunnel, the qualitative analysis of underground cavern excavation stability is made using software Unwedge and three - dimensional construction process simulation is made using finite element analysis software MIDAS/GTS. Research conclusions： （ 1 ） According to the results of the above comprehensive analysis it is suggested that a one time dismantling support length of the left and right holes can not exceed 6 m and 9 m. （2） In structural plane bedding sliding face pressure side walls and vault hollow bolt should be adopted to pass through the structure surface with large angle. （3） The surrounding rock pressure monitoring should be increased in bias and the pressure side wall of the back. （4） Support design and structural calculation should focus on considering the adverse effect of the bias. （5） The research results in this paper have certain reference value for the design and construction of similar tunnel in steep dip stratum.