基于失效概率的边坡降雨阈值曲面探讨

降雨是诱发边坡变形失稳的主要因素，而针对降雨型边坡的预警预报也一直是工程领域的核心问题。本文将蒙特卡罗方法引入降雨型滑坡的预警预报，首先基于正态分布的岩土体物理力学参数，建立了边坡的有限元数值计算模型，并分析了9种不同型式降雨下边坡稳定性系数的变化情况。结果显示递增型降雨对边坡的稳定性尤为不利，均匀型降雨次之，递减型降雨影响最小。其次，将降雨过程划分为前期降雨+当期降雨，并确定了前期降雨对于当期降雨的有效时间为6 d。最后，论文结合可靠度理论，选取失效概率P_f=10%作为预警指标，通过把前期降雨引入降雨强度-降雨历时关系曲线并作为第三坐标轴，最终将该曲线扩展成为前期降雨(A)-当期降雨(I)-降雨历时(D)曲面(A-I-D阈值曲面)，研究结果对于降雨型边坡的预警预报具有一定的指导意义。

Investigation on slope rainfall threshold surface based on failure probablolity

Rainfall is the main factor inducing slope deformation and instability, and the early warning and prediction of rainfall-triggered landslide has always been the core issue in the field of engineering. In this paper, the Monte Carlo method is introduced into the early warning and prediction of rainfall-triggered landslide. Firstly, based on the physical and mechanical parameters of rock and soil mass with normal distribution, the finite element numerical calculation model of slope is established, and the variation of slope stability coefficient under 9 different types of rainfall is analyzed. The results show that the incremental rainfall is particularly unfavorable to the stability of the slope, the uniform rainfall is the second, and the decreasing rainfallis the least. Secondly, the rainfall process is divided into antecedent and current rainfall, and the effective time of antecedent rainfall for current rainfall is 6 days. Finally, combined with the reliability theory, the failure probability P_f=10% is selected as the early warning index. By introducing the previous rainfall into the rainfall intensity-rainfall duration relation curve and taking it as the third coordinate axis, the curve is finally extended to the antecedent rainfall (A) - current rainfall (I) - rainfall duration (D) surface (A-I-D threshold surface). The research results have acertain guiding significance for the early warning and prediction of rainfall type slope.