昔格达地层隧道围岩稳定性及系统锚杆功效研究

昔格达地层隧道围岩水敏感性强,遇水易泥化,易造成围岩大变形、支护结构破坏和掌子面塌方等灾害。冉家湾隧道穿越昔格达地层,本文采用强度折减法对该隧道围岩稳定性进行数值模拟分析。结果表明:当含水率在20%以下时隧道具有一定的自稳能力,当含水率超过20%时隧道开挖需要采取超前支护措施;埋深小于45 m时埋深对昔格达地层隧道围岩稳定性影响显著,埋深大于45 m时,隧道围岩稳定性对埋深的敏感性降低;喷射混凝土对隧道安全系数的提升率大于设置系统锚杆;对于昔格达地层在天然含水率下,浅埋隧道破坏从拱部开始延伸至边墙,深埋隧道破坏从边墙开始蔓延至拱部。

Study on Stability of Surrounding Rock and Efficiency of System Bolt in Xigeda Stratum Tunnel

The surrounding rock of Xigeda stratum tunnel is highly sensitive to water and easy to be muddied when it encounters water.It is easy to cause large deformation of surrounding rock,damage of supporting structure,collapse of tunnel face and other disasters.Ranjiawan tunnel passes through Xigeda stratum.The strength reduction method was used to simulate the stability of surrounding rock of the tunnel in this paper.The results show that when the water content is below 20%,the tunnel has a certain self-stabilizing ability,and when the water content is above 20%,the tunnel excavation needs to adopt advanced support measures.When the buried depth is less than 45 m,the buried depth has a significant impact on the stability of surrounding rock of Xigeda stratum tunnel,and when the buried depth is more than 45 m,the sensitivity of the stability of surrounding rock to the buried depth decreases.The improvement rate of tunnel safety coefficient of shotcrete is greater than that of system bolt.For Xigeda stratum with natural water content,the damage of shallow buried tunnel extends from the arch to the side wall,and the damage of deep buried tunnel extends from the side wall to the arch.