降雨诱发含碎石夹层土坡破坏演化规律研究

Study on the Failure Evolution Mechanism of Soil Slope with Gravel Interlayer Under Rainfall Infiltration

含碎石夹层的土坡降雨作用下的渗透特性对边坡的稳定性具有重要影响。针对降雨诱发含碎石夹层土坡破坏演化规律的研究不足,通过概化含碎石夹层土坡的几何模型并构造相关受力分析模型,分析了碎石夹层优势渗透面对边坡稳定性的影响机制;基于Janbu法推导了考虑优势渗透面效应的极限平衡法公式,并基于Geostudio平台将其应用于数值计算;通过对工程实例的分析,研究了含碎石夹层土坡降雨作用下优势渗透面的形成过程及边坡破坏演化规律。结果表明:碎石夹层因其强渗透特性和受雨水汇集的影响,在降雨作用下容易沿碎石夹层向下形成优势渗透面,且优势渗透面效应随着降雨持时的增加而愈发显著;优势渗透面为雨水的快速下渗提供了通道,造成碎石夹层的抗剪强度急剧降低,边坡潜在滑动面的安全系数不断降低,最危险滑动面的空间位置由边坡上部不断向下演化直至发生滑坡。

The seepage characteristics of soil slopes with gravel interlayer(SSGI)under rainfall have an important influence on the stability of slopes.For the insufficient research on the failure evolution mechanism of SSGI induced by rainfall,the influence mechanism of the dominant seepage of gravel interlayers on slope stability is analyzed by generalizing the geometric model of the slopes and constructing related force analysis models.Based on the Janbu method,the limit equilibrium formula considering the effect of the dominant permeation is deduced and applied to the numerical calculation based on the Geostudio platform.Through the analysis of engineering examples,the formation process of the dominant seepage and the slope failure evolution mechanism under rainfall on SSGI are studied.The results show that the gravel interlayer is likely to form a dominant seepage under rainfall due to its strong permeability characteristics and the influence of rainwater collection,and the effect of the dominant seepage becomes more significant with the increase of the rainfall duration.The gravel interlayer provides a channel for the rapid infiltration of rainwater,which causes the shear strength of the gravel interlayer to decrease sharply:The safety factor of the potential sliding surface of the slope is continuously reduced,and the spatial position of the most dangerous sliding surface is continuously evolving downward from the upper part of the slope until a landslide occurs.