极限分析有限元法在节理裂隙隧洞中的应用

Application of Limit Analysis by Finite Element Methods in Jointed Tunnels

通过对节理裂隙隧洞非线性有限元模型进行强度折减,使隧洞达到不稳定状态,有限元计算将不收敛,此时的折减系数就是地下洞室的安全系数.同时折减岩体强度和结构面强度、只折减结构面强度,两种情况下得到的安全系数是一致的.将围岩塑性应变发生突变时的塑性区各断面中塑性应变值最大点的位置连成线得到了节理裂隙隧洞的破裂面.通过以上工作,评价了节理裂隙隧洞的稳定性和设计合理性,得出了几点有益的结论.

A stability analysis is made on the jointed tunnel by using the nonlinear FEM strength reduction method.With the c-φ reduction,the nonlinear FEM model of the jointed tunnel reaches instability and the numerical non-convergence occurs simultaneously.The safety factor is then obtained by the c-φ reduction algorithm.The safety factor is the same when reducing the c-φ of the rock and structural plane at the same time or just the structural plane.The failure surface of the jointed tunnel is obtained by locating the points of the biggest plastic strain in the plastic zone and linking them.Through the above work,the authors evaluate the stability and the rational design of the jointed tunnel.At last,the authors draw some useful conclusions for reference.