虎跳峡分岔大断面公路隧道稳定性分析

Stability Analysis of Bifurcated Highway Tunnels withLarge Section in Tiger Leaping Gorge

虎跳峡地下立交隧道是国内目前断面尺寸最大的山区地下立交隧道,施工时需要多方面考虑各断面的安全性。为分析虎跳峡大断面隧道的稳定性,建立有限元三维隧道模型,结合强度折减法,对围岩整体区域进行弹性模量、内摩擦角、黏结力参数折减,对围岩进行安全性分析,得到大断面隧道的安全系数为1.63。提取拉应变与位移数值结果可知:当围岩较为完整时,直接开挖后,围岩的整体变形较小,加固措施对于围岩的稳定性提高幅度有限,并且竖向位移模拟结果与现场的监测数据较为接近。

Tiger Leaping Gorge underground interchange tunnel is featured with the largest cross-section of its kind in China to date.The safety of different cross sections should be considered in manyaspects before construction.In order to analyze the stability of tunnels with different cross sections inTiger Leaping Gorge,a three-dimensional tunnel model is established by finite element analysis method.Combined with the strength reduction method,the elastic modulus and internal cohesive force parametersof the whole surrounding rock area are reduced,and the safety of the surrounding rock is analyzedaccording to the results.Finally,the safety factor of the surrounding rock at the large section is 1.63.Theeffects of lining supporting and bolt supporting on the displacement and tension strain disturbance zone ofsurrounding rock are explored.The numerical results of tension strain and displacement show that theimprovement of surrounding rock stability is limited by reinforcement measures,and the change of tensionstrain disturbance zone is also small when the rock is intact,and the results are close to the displacement offield monitoring data.