岩体参数敏感性分析对边坡稳定性评价影响研究——以大岗山坝肩边坡为例

Sensitivity analysis of the effect of rock mass parameters on slope stability evaluation: A case study of abutment slope of Dagangshan

模糊评判系统在边坡稳定性综合评价中的应用越来越广泛。由于岩体材料参数在实际工程中是离散的,将材料参数作为评价因子时,需首先对其本身进行评价得出表征参数,然后再参与到综合评价系统中。以大岗山坝肩边坡为例,从岩体自身抵抗外界影响的角度出发,考虑到位移和安全系数在边坡失稳前、后的变化幅度和变化次序问题,对岩体特性进行深入研究。通过对各参数进行分层敏感性分析并评价,得到表征参数;通过面积分配法得到隶属度;以安全系数和位移两个目标量,对岩体物理力学参数进行综合敏感性分析,以敏感度定义各因子的权重,将其结果应用于评价系统中。敏感性分析结果显示:以位移为目标量时,变形主要依赖于抗剪强度参数中的凝聚力;以安全系数为目标量时,内摩擦角对边坡失稳的影响略大于凝聚力;位移敏感性强于安全系数敏感性。综合评价结果显示:岩体力学参数具有较强的强度,以安全系数为目标量的评价结果优于以位移为目标量的评价结果,与敏感性分析结果一致,符合一般规律和实际情况,从而证明研究方法的正确性。

Fuzzy evaluation systems have been widely applied to comprehensively evaluate the slope stability. When material parameters of rock masses are used as evaluation factors, due to their discreteness in practical engineering, these parameters are required to be evaluated in advance to obtain characterization parameters. Then the characterization parameters are employed in comprehensive evaluation. From the viewpoint of rock masses resisting on external interactions, the characteristics of rock masses of Dagangshan abutment slope are studied in depth by considering the range and sequence of deformation and the safety factor before and after slope failure. Specifically, these characterization parameters are obtained by analyzing layered sensitivity and evaluating each parameter and the membership degree is derived by the area distribution method. Besides, the comprehensive sensitivity of mechanical parameters of rock masses is investigated by referring safety factor and the displacement. The weight of each factor is further determined by its sensitivity, and then applied in the comprehensive evaluation system. It is found that the deformation of rock masses mainly depends on cohesion when the displacement is regarded as reference. The frictional angle has more effect on slope failure than the cohesion when the safety factor is regarded as reference. The results also indicate that the sensitivity characteristics of displacement are better than those of safety factor. The results of comprehensive estimation reveal that rock masses have a group of intensive mechanical parameters. It is also noticed that evaluation results are better when the safety factor is used as reference, which is in accordance with the results of sensitivity analysis and practical circumstance, and thus the reasonability of the proposed method is verified.