溶腔与隧道拱顶间预留岩塞厚度的计算方法

针对隧道拱顶遭遇充填溶腔时的岩塞安全厚度问题，基于极限分析原理构建合理的破坏模式，推导出优化过程，并用该方法得到Ⅰ~Ⅴ级围岩条件下对应的岩塞安全厚度.研究结果表明，随着围岩质量的逐级降低，岩塞安全厚度逐渐增大.此外，将该方法应用至“宜万铁路”大支坪隧道，良好的数值结果验证了方法的正确性.

Method for Calculating Rock Plug Safe Thickness in Karst Tunnels

In view of a filled karst cave existing on the tunnel vault and based on the limit analysis theorem，a proper failure pattern is established and the specific procedures are deduced to derive the expression of rock plug thickness.Then，the proposed method is adopted to calculate the rock plug thickness corresponding the surrounding rock ranging from levelⅠtoⅤ.The results indicate that with the decrease of surrounding rock strength，the thickness increases continuously.Moreover，applying the method to the engineering projects of Dazhiping Tunnel of the Yichang-Wanzhou Railway，the reasonable results were obtained，which verified the validity of the proposed method.