切割斜坡断层的几何形态对斜坡地震响应影响研究

与一般重力环境的滑坡相比，地震诱发滑坡在形成机理、运动特征等方面差异显著。天然和降雨条件下，断层破碎带作为边坡的不连续结构面，往往对斜坡的稳定性产生不利影响。而在地震作用下，边坡内部的断层破碎带存在一定的滤波作用，有可能减弱边坡的地震动响应。为了探究逆断层几何形态对边坡地震动响应的影响，以汶川地震中牛眠沟滑坡、窝前滑坡、谢家店子滑坡及东河口滑坡为研究对象，概化出断层切割型斜坡的地质模型，利用3DEC离散元软件对不同断层破碎带宽度、倾角、位置情况下的斜坡地震动响应进行模拟。模拟结果表明：（1）随着断层倾角增大，斜坡总位移峰值和坡面加速度峰值表现出增大的趋势，斜坡更易失稳；（2）坡顶监测点的峰值加速度一般大于坡底与坡腰的值，随着断层破碎带宽度增大，对斜坡地震动响应的直接影响愈加明显；（3）断层的存在会增加斜坡失稳的可能性，断层位于坡顶时斜坡地震动响应随断层倾角和破碎带宽度变化的规律性更明显。本研究可为深入揭示地震作用下断层破碎带对斜坡稳定性的影响提供理论依据。本研究可为深入揭示地震作用下断层破碎带对斜坡稳定性的影响提供理论依据。

A study of the influence of the crossing-slope fault geometry on the slope seismic response

Compared with the landslides in the general gravity environment, the earthquake-induced landslides are significantly different in formation mechanisms and kinetic characteristics. Under the normal and rainfall conditions, the fault fracture zone, as the discontinuous structural plane of the slope, often adversely affect the stability of the slope. Under the earthquake condition, the fault fracture zone within the slope has a limited filtering effect, which could weaken the seismic response of the slope. To investigate the influence of the reverse fault’s geometry on the slope’s seismic response, we took the Niumiangou landslide, the Woqian landslide, the Xiejiadianzi landslide and the Donghekou landslide as reference objects and generalized the geological model of the fault-crossing landslide in this study. The seismic response of slopes with faults of different widths, dips and positions are simulated using the 3DEC discrete element software. The simulation results show that (1) as the fault dip angle increases, the peak value of the total displacement of the slope and the peak acceleration of the slope surface show an increasing trend, and the slope stability is worse. (2) The peak acceleration of the monitoring point at the top of the slope is generally greater than that at the bottom and waist of the slope. As the width of fault fracture zone increases, the effect on the seismic response of the slope becomes obvious.(3) The presence of faults facilitates the probability of slope instability. When the fault is located at the top of the slope, the variation of the seismic response with the dip angle and the fault width shows a more obvious regularity. This study can provide a theoretical basis for further revealing the impact of fault fracture zone on the stability of slopes under the earthquake condition.