非均质边坡稳定性上限分析评价研究

Evaluation on upper limit of heterogeneous slope stability

边坡稳定性评价研究是土力学经典问题。为研究非均质边坡稳定性问题,以上限分析法为理论基础,建立非均质边坡分段对数螺旋线破坏机构。应用拟合多项式近似描述对数螺旋线,计算破坏机构外力功率和内能耗散率,应用设计的计算流程进行强度折减循环计算,使边坡逐步过渡至极限平衡状态,确定边坡安全系数。以某露天矿南帮边坡为工程背景,经过反复强度折减,最终确定安全系数,通过变换初值的方式验证计算流程的稳定性,应用严格Morgenstern-Price法验证计算结果的准确性。研究结果表明:该流程性能稳定,不受初始值影响。相比于严格Morgenstern-Price法,二者安全系数计算结果偏差小于5%,可充分满足工程实践要求。同时,上限分析法求得的最危险滑面满足速度分离关系,具有更强的工程参考价值。

Slope stability evaluation is a classic problem for soil mechanics. In order to study the stability of heterogeneous slopes, this paper uses the upper limit analysis method to establish the failure mechanism of segmented logarithmic spiral arcs for heterogeneous slope. Then fitting polynomial is used to approximately describe the logarithmic spiral arcs. External force power and internal energy dissipation power of the failure mechanism can be determined. The calculation process is applied to repeat the strength reduction until the slope gradually transition to the ultimate balance and the slope stability factor can be obtained. Taking the south slope in an open-pit mine as the background, the slope stability factor is determined by the method of repeated strength reduction. The stability of the calculation process is verified by the method of changing initial value, and the accuracy of the calculation result is verified by the method of strict Morgenstern-Price. The results show that the process is stable and is not affected by the initial value. Compared with the strict Morgenstern-Price method, the difference of stability factor calculation results between the two methods is less than 5%. The stability factor calculation results can fully satisfy the requirements of engineering practice. At the same time, the most dangerous slip surface formed by upper limit analysis method can satisfy the speed separation relationship.