Most of the slope failure occurs mainly during heavy rainfall,but there are different opinions about the mechanism of rainfall on slope failure.It is found that the crack propagation inside slopes caused by heavy rainfall should be the main factors causing the slope instability.If the cracks in the slope form a microscopic drainage channel during the rainfall,the soil cohesion of the slope appears as behaving like sand when subjected to heavy rainfall.The permeability coefficient of site soil is much higher than that of geological exploration report during heavy rainfall,the actual safety factor of slope is much lower than that of conventional calculation.The ordinary triaxial test is no longer applicable to obtain the soil parameters,the modified direct shear test is suggested,and the stability of the slope can be ensured by setting up sub-drains system inside the slope or using ground anchor with high prestressing loads.%大多数边坡失稳主要在强降雨时发生,但是降雨对边坡失稳作用机理众说纷纭.研究发现:强降雨导致的边坡内部裂缝扩展是边坡失稳的主要因素;若边坡裂缝在降雨时形成微观的排水通道,则边坡在遭受强降雨时土体黏聚力表现类似于砂;强降雨时现场土的渗透系数比地勘报告中高得多,边坡实际的安全系数比常规计算值低得多,普通三轴试验不再适用于获取土体参数,建议采用修正直剪实验获取土体的强度参数,并采取边坡内设置排水系统或使用高预应力地锚等方法来保证边坡的稳定性.
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