考虑地震效应和坡顶超载的多级边坡稳定性非线性能耗分析

Nonlinear energy consumption analysis of multi-stage slope stability subjected to seismic effect and surcharge

多级边坡常承受复杂荷载影响,且现有多级边坡稳定性分析大多基于线性破坏准则,而岩土体破坏往往呈现非线性特征.为详细分析基于岩土材料非线性特征下多级边坡在不同工况时的安全性能,基于极限分析上限定理和强度折减技术,结合非线性破坏准则,考虑地震效应和坡顶超载的影响,构建边坡对数螺旋线非线性能耗分析模型,根据虚功原理推导出边坡安全系数解析式;采用序列二次规划迭代方法,通过MATLAB优化计算,运用蒙特卡罗边坡可靠度方法,结合边坡工程案例探讨了非线性系数、地震效应及坡顶超载对三级边坡稳定性、潜在滑动面位置及可靠度指标的影响规律.研究结果表明:随着非线性系数、地震效应比例系数、坡顶超载的增大,边坡安全系数显著降低,可靠度指标逐渐减小,失效概率不断增加,边坡发生失稳的可能性逐步递增,在复杂工况下其发生失稳的范围更大;若非线性系数取值越低,会越高估复杂荷载对边坡稳定性的影响,不利于正确评估其稳定性;随着非线性系数、坡顶超载的增大,地震效应比例系数的减小,边坡坡顶滑出点与坡肩距离逐渐增加,潜在滑动面逐步向坡内偏移,失稳发生的范围显著加大;当地震效应比例系数、坡顶超载越大时,非线性系数对边坡稳定性影响越显著;随着非线性系数越大、坡顶超载越小,竖向地震效应对边坡稳定性影响越明显;而当地震效应比例系数越小、非线性系数越大时,坡顶超载对边坡稳定性影响越显著,在坡顶超载为0~20 kPa阶段尤为明显,类似边坡工程设计时应重点注意.

Complex loadings often affects multi-stage slopes stability,and the existing stability analysis of multi-stage slopes is mostly based on linear failure criteria,while the failure of rock and soil often presents nonlinear characteristics.In order to analyze the safety performance of multi-stage slopes under different working conditions based on nonlinear characteristics of geotechnical materials in detail,based on the upper bound theorem of limit analysis and strength reduction technique,combined with the nonlinear failure criterion,considering the influence of seismic effect and surcharge,constructing the logarithmic spiral nonlinear energy consumption analysis model of slope.According to the principle of virtual work,the safety factor formula of slope was derived.Using MATLAB optimization calculation and Monte Carlo slope reliability method,combined with slope engineering examples,the influence of nonlinear parameter,seismic effect and surcharge on the stability,potential sliding surface position and reliability index of three-stage slope were discussed.The results show that the slope safety factor decreases significantly with the increase of nonlinear parameter,seismic effect proportional parameter and surcharge.The slope under complex working conditions has a larger range of instability.When nonlinear parameter is lower,the influence of complex loadings on slope stability will be overestimated,which is not conducive to the correct evaluation of its stability.With the increase of nonlinear parameter,surcharge and the decrease of seismic effect,the distance between slope top sliding point and shoulder of the slope gradually increases,the potential sliding surface gradually shifts to the slope,the range of slope instability increases significantly,the reliability index decreases gradually,and the failure probability of the slope increases continuously.When seismic effect and surcharge are larger,the influence of nonlinear parameter on slope stability is more significant.When nonlinear parameter is larger and surcharge is smaller,the influence of seismic effect on slope stability is more significant.When seismic effect is smaller and nonlinear parameter is larger,the influence of surcharge on slope stability is more significant,especially in the stage of 0–20 kPa of surcharge,which should be paid attention to in the design of similar slope engineering.