地震作用下呷爬滑坡的变形特征分析

Deformation characteristics analysis of Gapa landslide under seismic effects

运用有限差分软件FLAC^(3D),建立了呷爬滑坡体三维模型,分别施加1倍和3倍El-Centro地震波。计算结果表明,1倍地震波作用下会发生一定的永久位移,但不会滑动失稳;3倍地震波作用下将发生滑动失稳。进一步发现边坡在1倍和3倍地震波激励下的变形滑移特征不同,第一种情况属于累积效应阶段,变形主要集中于滑体Ⅲ,第二种情况属于触发效应阶段,滑体Ⅰ的滑动变形同样剧烈。文中从滑坡体的组成物质和材料参数、滑动区域的地形因素和滑动区域的动力响应三方面进行了分析。运用Newmark有限滑动位移法,基于滑体Ⅰ和滑体Ⅲ的加速度响应时程,计算了两者的永久位移,结果与数值计算吻合良好。表明滑体Ⅲ处的动力响应会产生更大的永久位移,从而验证了数值计算的结果。同时,基于结构动力响应而计算得到的永久位移也可以作为衡量地震作用对该处结构变形影响的指标,从而估计地震对局部结构的破坏作用。

We established a three-dimensional Gapa landslide model using the finite difference software FLAC^（3D）,and applied to it the El-Centro seismic wave magnified by one and three folds respectively.The calculation results showed that the slope would be permanently displaced under the effect of single-fold seismic waves,but would not slide;under three-fold seismic waves,the slope would slide.Moreover,the slope had different deformation and slippage characteristics when agitated by single-fold and three-fold seismic waves.In the first case,the deformation mainly concentrated on the sliding body Ⅲ;but in the second case,the sliding bodyⅠ also had intense deformation.We analyzed this phenomenon from three aspects：the components and materials parameters of the landslide,the topographic factors of the slide region,and the dynamic response of the slide region.We calculated the permanent displacement of sliding bodies I and III using the Newmark finite sliding displacement method,and the results were consistent with the numerical calculation.The results showed that the dynamic response of sliding bodyⅢ would result in greater permanent displacement,and thus verified the numerical calculation.The permanent displacement obtained based on structural dynamic response can also be used as an index of the impact of earthquake on local deformation,and thus to estimate the damage of an earthquake.