基于上限定理的含裂缝边坡稳定性图表分析方法

Graphic Analysis Method for Stability of Cracked Slopes Based on Upper Limit Theorem

大量地灾现场勘测发现,滑坡外表面广泛分布着裂缝,在地震、静水压力、边坡超载等条件下均会加剧裂缝边坡失稳。为详细分析含裂缝边坡在不同条件下的安全性能,文章通过强度折减法结合极限分析上限定理,建立了综合性分析任意深度、位置的临界裂缝边坡稳定性的评估方法,推导得到安全系数求解方程,并优化了算法:将随机搜索法与非线性序列二次规划法相结合,解决计算中的大量迭代问题和易陷入局部最优解等问题;还原了裂缝边坡的形态并与经典结构、有限元计算结果对比验证。结果表明:与经典解相比,优化后算法显著提高计算稳定性与准确性;不同的工况条件会对边坡稳定性产生较大的影响;相同参数设计下,不利的工况易产生更深的裂缝。最后利用研究结论绘制了一系列的安全性图表,可作为工程师进行边坡安全性初步快速评估的依据。

A large number of road and disaster site surveys have found that unfavorable cracks are widely distributed on the outer surface of the slope,and failure conditions such as seismic load,hydrostatic pressure,and surcharge load will increase the risk of crack slope instability.In order to analyze the safety performance of slope with different kinds of cracks under different failure conditions in detail,a comprehensive evaluation method for the stability of slope with crack under any depth and location by combining strength reduction method and upper bound limit analysis were established,also the equation of safety factor was derived.The algorithm was optimized at the same time.The random search method was combined with the nonlinear sequential quadratic programming method to solve a large number of iterative problems and easy to fall into the local optimal solution.The shape of the fractured slope was restored and compared with the classical structure and finite element calculation results.The results show that the optimized algorithm significantly improves the stability and accuracy of the calculation compared with the classical solution,a greater impact on the stability of the slope would be influenced by different failure conditions.Deeper and more distant cracks tend to occur under more adverse different failure conditions under the same parameter design.Finally,a series of safety charts are drawn using the conclusions,which can be used as an initial assessment of slope safety by engineers.