水平向与竖向地震动的时间遇合模式对边坡动力安全系数的影响

通过沿滑面的应力积分法和动力时程分析法，研究了水平向、竖向地震动单独作用对边坡动安全系数的影响，发现竖向地震动与水平向地震动一样也对边坡抗震稳定性有显著的影响。在此基础之上，重点探讨了实际地震的双向地震动同时作用时，其时间遇合模式对动力安全系数的影响，结果表明，常用的加速度峰值遇合模式和随机遇合模式都不能充分体现出竖向地震动与水平向地震动的叠加效应，进而造成对安全系数的高估；文中提出的最大地震作用效应遇合模式才是最危险的遇合模式，其所得稳定性安全系数时程的极值更小。在考虑多向地震的边坡抗震分析中，由于多维地震动的强烈随机性，应考虑出现这种最大地震作用效应遇合的可能性，以得到工程设计中偏于安全的动力稳定性安全系数值。

Influence of time combination pattern of horizontal and vertical ground motions on slope seismic safety factor

Firstly, influence of only horizontal or vertical earthquake loading on slope seismic safety factor is examined using stress integration along sliding surface and the dynamic FEM time-history analysis method. It is shown that under most conditions the vertical ground motion has the same significant effect on slope stability as the horizontal earthquake motion. Then, the effects of the time combination pattern of horizontal and vertical accelerograms on the dynamic safety factor are considered. It is concluded from the analysis results that the pattern with peak acceleration values meeting in time domain and the random time combination pattern may lead to over estimation of safety factors because of not giving the most significant superimposing effect for the vertical earthquake loading and the pattern with maximum action effects meeting in time domain is the severest pattern which allows for the minimum value of safety factor to be obtained. Due to the largely unknown behavior and random nature of earthquakes, the possibility for the pattern with maximum action effects meeting in time domain should be considered for slope under multiple-dimensional earthquake action to get the more conservative safety factor for the engineering design.