地震及降雨作用下路堤边坡变形破坏特性研究

Deformation and Failure Characteristics of Embankment Subjected to Earthquake and Rainfall

为了探究地震和降雨耦合作用下路堤边坡稳定性演化以及变形破坏特性,基于离心模型试验和有限元数值模拟方法,针对降雨、地震后降雨、考虑初始降雨的地震后降雨等不同工况下边坡渗流、变形及失稳破坏过程进行了研究,并将试验结果与模拟结果进行对比,分析了地震动力荷载作用对路堤边坡变形的影响以及地震后降雨过程中路堤边坡孔压发展特点、变形演化规律与失稳破坏特征。研究结果表明:地震导致路堤边坡土体不连续变形以及表面张拉裂缝产生,滑移面上土体变形在下部最为明显和集中,且随着土体高度的增大而逐渐减小;与均质路堤边坡相比,含地震裂缝的路堤边坡在地震后降雨下,坡内孔压的发展更为迅速、增幅更大,且土体变形受地震裂缝的影响较大,主要沿着坡肩附近裂缝发展,而均质路堤边坡在降雨中的变形延伸至距离坡肩较远位置;前期降雨增湿作用造成路堤边坡土体饱和度增大和有效应力降低,地震作用下边坡变形明显,地震后降雨导致路堤边坡失稳启动时间提前且变形破坏更为迅速。

In order to investigate the stability as well as deformation and failure characteristics of embankment under the combined effect of earthquake and rainfall,this study carried out centrifuge model tests and finite element numerical simulations,where the deformation and failure of embankment subjected to different conditions such as rainfall,post-earthquake rainfall,and post-earthquake rainfall considering the influence of initial rainfall were analyzed.Based on that,the effect of earthquake on the deformation of embankment was examined,after which the development of pore water pressure,evolution of deformation,and characteristics of failure of embankment during post-earthquake rainfall were studied.Results show that earthquake causes the discontinuity in soil deformation and occurrence of surface tension cracks of the embankment.The soil deformation on the sliding surface is most significant and concentrates in the lower part,and decreases gradually with the increase of soil height.Compared with the homogeneous embankment,the pore water pressures of the embankment with earthquake-induced cracks rise more rapidly to the higher level under rainfall after earthquake,and the soil deformation is greatly affected by the cracks,which mainly develops along the cracks near the embankment shoulder,while the deformation of the homogeneous embankment extends to the far position away from the embankment shoulder.The soil saturation of embankment increases and the effective stress decreases as a result of the rainfall-induced wetting effect in the initial stage,thus the deformation of the embankment becomes obvious under earthquake,causing the instability of embankment to be earlier and the deformation and failure more rapid during the post-earthquake rainfall.