中文摘要：

川东红层地区在强降雨条件下极易产生群发性平缓岩层滑坡,其成因一直存疑。采用现场降雨入渗观察、室内试验等手段重点探讨川东红层岩质斜坡降雨入渗规律和滑坡成因机制。研究发现：以裂缝为主的通道为降雨入渗提供途径,雨水进入潜在滑面后会对滑带土形成软化作用。室内软化试验结果表明：原状滑带土饱水软化10 d后,黏聚力和内摩擦分别由天然时的20.76 k Pa和21.2°衰减至11.39 k Pa和4°,当泥化夹层重塑样含水率配至50%时,其抗剪强度仅为1.28 k Pa和1.24°。以此为基础归纳2类滑坡失稳模式：蠕滑–拉裂型是由于滑带土软化后强度降低引起的,平推–滑移型则主要是在后缘静水压力、底滑面扬压力和滑带土软化综合作用下发生失稳的。推导的极限平衡公式可为红层滑坡稳定性评价和防治工程提供有益参考。

英文摘要：

Large area and batches of rock landslides happened in gentle inclined red bed stratum in the east of Sichuan province after heavy rainfall,however,the causes of the landslides are still in doubt. With the help of great field landslides＇ rainfall infiltration observation and indoor experiments,this paper mainly discussed the rainfall infiltration regularities and formation mechanism rock landslides in red stratum in the east of Sichuan province. The study finds that rainfall seeps into slopes mainly by cracks and will have softening effects on sliding soil. The results of indoor softening experiments show that undisturbed sliping soil＇s cohesion and angle of internal friction decrease from 20.76 k Pa,21.2°to 11.39 k Pa,4°after 15 days＇ saturated softening experiments. The shear strength of muddy layer reachs 1.28 k Pa and 1.24°. According to the results,two types of rock landslides＇ failure modes are summarized：Creep-sliding failure mode happens with the result of sliding soil＇s shearing strength parameters reduction after softening and translational-sliding failure mode occurs on the effects of hydrostatic-pressure in the cracks distributing in the trailing edge of slope,uplift pressure on the sliding surface and sliding soil＇s softening impact. The limit equilibrium formula in this paper can provide the beneficial reference to landslides＇ stability evaluation and prevention project on red bed stratum.