不同偏压大断面浅埋隧道施工力学分析及优化

大断面隧道穿越地势起伏的地层环境时,地层偏压情况往往不同,在不同的偏压情况下选择合理的施工方法对控制大断面隧道施工力学性能具有重要意义。通过对双侧壁导坑法、改进台阶法、交叉中隔壁(CRD)法的数值模拟,分析不同偏压情况下的大断面浅埋隧道施工中的位移控制效果与支护承载情况。结果表明:当地表倾角为0～10°时,宜采用改进台阶法;当地表倾角为10～20°时,优先选择改进台阶法,同时应加强支护并及时监测;当地表倾角为20～30°时,宜采用双侧壁导坑法。

Mechanical Analysis on and Optimization of Construction of Asymmetrical-loaded Large Cross-section Tunnels under Shallow Cover

When large cross-section tunnels run through ground with uneven terrain, different asymmetrical earth pres- sures are always encountered. Therefore, selecting rational construction methods is very important for the control of the construction mechanical performance of asymmetrical-loaded large cross-section tunnels under shallow cover. In the pa- per, analysis is made on the displacement control and support stress of asymmetrical-loaded large cross-section tunnels under shallow cover, by means of numerical simulating on double side drift method, optimized bench method and CRD method. The results show that ： 1 ） When the ground surface inclination angle ranges from 0° to 10°~, optimized bench method should be adopted ; 2） When the ground surface inclination angle ranges from 10° to 20°, optimized bench method should be adopted and the support should be strengthened and timely monitoring should be executed; 3） When the ground surface inclination angle ranges from 20° to 30°, double side drift method should be adopted.