黄土边坡动力响应分析

Dynamic Response Analysis of Loess Slope

运用有限差分软件FLAC3D,建立了某一黄土边坡三维模型,首先对其在地震作用下的动力响应规律进行了总结,然后探讨了地震动参数对黄土边坡动力响应的影响。结果表明:黄土边坡对地震波存在垂直放大和临空面放大作用;当输入地震波振幅或频率增加时,坡面监测点加速度放大系数随坡高增加呈"增加→衰减→增加"的三段形态;速度放大系数随坡高的增大而增大,并在坡顶达到最大值;位移放大系数随振幅和频率的增加而增加;地震持时对加速度、速度峰值的影响不大,但坡体位移随持时的增加而显著增加。强震作用下的最大剪应变增量区域的位置和形状表明,黄土边坡的破坏模式仍是沿着某一弧形潜在滑动面失稳破坏。研究结果有助于进一步揭示黄土边坡在地震作用下的失稳机制,为黄土地区边坡抗震设计与防灾减灾提供参考。

A three-dimensional dynamic numerical simulation model of loess slopes was established with FLAC3Dprogram, the dynamic response laws and the influence of parameters of ground motion on the responses of slopes under earthquakes were analyzed. It is shown that the input seismic waves are affected by vertical and surface amplification of the slopes l with increase of amplitude and frequency of input seis- mic wave, the amplification factors of PGA at monitoring points on slope surface display a pattern of three segments of increase, decrease and increase as the height of slope increases; amplification factors of PGV and PGD increase with the amplitude and frequencys increasing; while these factors are less affected by the duration~ slope displacement increases obviously with duration increasing; the location and the shape of the maximum shear-strain increment region under the action of strong earthquake show that the failure pattern of homogeneous loess slopes under earthquakes is still the instability along a potential sliding sur- face, similar to that under static condition. Results can help further reveal the failure mechanism of loess slope under earthquake and give a reference to seismic design of slope in loess regions and to disaster pre- vention and reduction.