The events of landslides induced by the combined effect of earthquakes and rainfall are more dangerous than those induced by earthquake or rainfall. The Yongguang loess landslide induced by the Minxian–Zhangxian M_s 6.6 earthquake in 2013 is a typical example of a landslide induced by the combined effect of an earthquake and rainfall. A few scholars have carried out relevant research on this landslide, but the initiation mechanism of this kind of landslide has not been elucidated. Therefore, the initiation mechanism of loess landslide under the combined effect of earthquakes and rainfall is studied through indoor geotechnical tests, shaking table slope model tests and numerical simulations. The indoor geotechnical tests show that the mechanical properties of Q3 loess would change significantly (the mechanical strength would decrease sharply) when soaked in water and that its strength would be further lowered under dynamic action. The slope model test results show that the infiltration depth at the slope top is deeper than that of the slope surface after continuous heavy artificial rainfall and that the natural frequency of the shoulder of the front edge of the slope top is closer to the frequency of the loading wave than it is in other parts of the slope; so the amplification effect of the seismic ground motion at the shoulder of the front edge of the slope top is more significant and the soil damage is more serious under seismic dynamic action. With the rapid increase in the residual deformation and pore water pressure of the soil mass, the loess properties change substantially, that is, loess liquefaction occurs when the pore water pressure and residual deformation reach a certain threshold. Under the action of the subsequent seismic ground motion, the liquefied loess mass of the front edge of the slope top rushes out along the sliding bed and slides down the slope surface in the form of a loess mudflow; that is, a mudflow-like loess landslide is induced. A simplified mechanical model is used in the numerical simulation test and can reproduce the triggering process of this kind of loess landslide. In this research, the initiation mechanism of mudflow-like loess landslide induced by the combined effect of earthquakes and rainfall is revealed by comprehensively considering a variety of test results, and a sliding distance calculation formula is proposed, providing a foundation for the prevention and control of this kind of landslide disaster.

地震和降雨共同作用引起的滑坡事件比地震或降雨引起的滑坡事件更加危险。诱导岷县-漳县永光黄土滑坡中号_小号在2013 6.6地震是由地震和降雨的组合效应引起的滑坡的一个典型例子。少数学者对该滑坡进行了相关研究，但这种滑坡的形成机理尚未阐明。因此，通过室内岩土试验，振动台边坡模型试验和数值模拟研究了黄土滑坡在地震和降雨共同作用下的萌发机理。室内岩土试验表明，浸泡在水中的Q3黄土的机械性能会发生明显变化（机械强度会急剧下降），并且在动力作用下其强度会进一步降低。边坡模型试验结果表明，连续大量人工降雨后，坡顶的入渗深度大于坡面的入渗深度，并且坡顶的前缘肩部的固有频率接近坡面的入渗频率。比斜坡其他部分的荷载波大；因此，在地震动力作用下，斜坡顶部前缘的肩部的地震地震动的放大作用更为显着，土壤破坏更为严重。随着土体残余变形和孔隙水压力的迅速增加，黄土性质发生了较大变化，即当孔隙水压力和残余变形达到一定阈值时发生黄土液化。在随后的地震地震动的作用下，斜坡顶部前缘的液化黄土块沿着滑床冲出，并以黄土泥浆的形式滑下斜坡表面。即，诱发了泥石流状的黄土滑坡。简化的机械模型被用于数值模拟测试中，并且可以再现这种黄土滑坡的触发过程。在这项研究中