地震荷载对滑坡稳定性的影响评估——以甘肃舟曲南桥滑坡为例

通过实现Druker-Prager屈服准则与Mohr-Coulomb理论等效原则, 采用ANSYS软件模拟, 分别就自重和暴雨状态下施加地震荷载构成不同工况组合, 分析评价了地震荷载对甘肃舟曲南桥滑坡稳定性的影响.以有限元强度折减法为基础, 分别在不同地震设防烈度等级下, 通过改变折减系数计算水平位移最大值和塑性区应变最大值, 以出现突变点、计算不收敛和塑性区贯通来判别土体破坏, 得到不同地震设防烈度下滑坡稳定系数.结果表明:在自重+地震与暴雨+地震工况条件下, 稳定系数差值为0.25~0.32, 为2种工况的相互校核和理论推算提供了参考.有限元强度折减法与极限平衡法的对比分析表明, 二者误差以小于5%为主, 考虑地震工况比不考虑地震工况的滑坡稳定系数下降13%~16%, 进一步验证了数值模拟计算的精准度和可靠性以及滑坡治理中抗震设防的重要性.计算结果符合实际, 在科研和实际设计中值得推广.

The Impact Assessment of Earthquake on Landslide Stability-A Case Study of Landslides in Nanqiao Village,Zhouqu, Gansu

Based on the equivalent of Druker-Prager (abbreviated DP) yield criterion and the Mohr-Coulomb (abbreviated MC) theory, by the simulation of ANSYS software, the influences of earthquake on the stability of landslide in Nanqiao village under the conditions of its weight and rainstorm respectively were estimated. The results show that on the different intensity level of seismic fortification by changing the reduction factor to calculate the maximum of the horizontal displacement and plastic strain. To distinguish the destruction of landslide based on the abrupt point occurs and the calculation does not converge and the plastic zone penetration. So the landslide stability factor of different seismic fortification intensity had been obtained. Under the condition of weight add earthquake and rainstorm add earthquake, the discrepancy of the stability factors is between 0.25 and 0.32, which offered the possible for the mutual verification and theoretical calculations of the two conditions. The comparative analysis of the Finite Element Strength Reduction and the Limit Equilibrium Method showed that the errors of less than 5% are primary, when considering earthquake the stability coefficient of landslide will decrease by 13% to 16%. And the accuracy and reliability of numerical simulation were verified further. The result of calculation is consistent with the actual results. So this research should be promoted in scientific research and the actual design.