地震荷载作用下岩石边坡稳定性的拟动力分析及可靠度研究

Pseudo-dynamic Analysis and Reliability Study of Stability of Rock Slope Under Seimic Load

岩石边坡的稳定性直接关系到人类的生命和财产安全,因此其安全性评估至关重要,特别是在地震易发地区。安全系数是评估边坡安全程度的常用方法之一,然而影响边坡安全性的因素较多,存在一定的不确定性;因此在岩石边坡抗震设计中存在一定的不足。考虑地震荷载、岩体放大系数、张缝内水位变化等影响因素,利用拟动力方法推导了出流缝未堵塞时不同工况下的岩石边坡抗倾覆性的安全系数。在确定性计算模型的基础上,考虑到地震荷载等因素的不确定性,建立了地震荷载作用下岩石边坡抗倾覆性的极限状态方程。通过可靠度指标对计算参数的敏感性分析,分析了水平及竖向地震荷载、岩体放大系数、张缝内水位变化等控制因素的影响作用。分析表明,岩石边坡的抗倾覆稳定性不仅与计算参数的均值有关,也与计算参数的变异性有关。因此,在抗震设计当中,同时利用安全系数及可靠度指标来评估岩石边坡的抗震稳定性,有利于岩石边坡的安全设计。

The stability of the rock slope is directly related to the human＇s life and property.It is critically important for the safety evaluation of the rock slope,especially for the earthquake-prone district.The method of the safety coefficient is a usual method for the evaluation of the stability of the rock slope.However many factors could influence the stability of the rock slope,and there exists the uncertainty among these influencing factors.Hence,it is not reasonable enough for the seismic design of the rock slope.Several influencing factors including horizontal and vertical seismic forces,dynamic amplification factor,depth of the water in the tension cracks are considered.Pseudo-dynamic method is employed to deduce the safety coefficients of the rock slope＇s overturning stability in different conditions supposing that the outflow is fully unplugged.Based on the deterministic calculation model,considering the uncertainty of the factors including the seismic forces,the limit state equation of overturning stability of rock slope is developed.Through the sensitivity analysis of the reliability indexes,the effects of the controlling factors including seismic forces,dynamic amplify coefficient,depth of the water in the tension crack are analyzed.The analysis results show that the anti-overturning stability of the rock slope is affected by not only the mean values of the factors,but also the variation of these influencing factors.Hence,for the seismic design of the rock slope,it would be more reasonable when the method of safety coefficient and the reliability analysis are combined to estimate the anti-seismic stability.