含软弱夹层顺层岩质边坡动力破坏模式的能量判识方法研究

基于希尔伯特–黄变换和边际谱理论,进行了含软弱夹层顺层岩质边坡的大型振动台试验,并利用试验结果对含软弱夹层顺层岩质边坡动力破坏模式的能量判识方法进行了研究,结果表明:边际谱峰值和特征频率的变化能清晰地表征边坡内部的震害损伤发展过程;地震作用下含软弱夹层顺层岩质边坡的损伤首先出现在坡肩位置,随着地震动强度的增大,震害损伤逐渐向低高程发展,最终边坡在坡体中上部相对高度0.56处沿软弱夹层顺层剪出,试验中坡面的位移监测结果表明坡体中上部位移出现陡增时刻晚于坡肩,边际谱分析结果与位移监测结果吻合较好;坡面附近的震害程度强于坡体内部;边坡中下部特征频率发生突变,表明坡体中下部为边坡动力响应的不连续带;含软弱夹层顺层岩质边坡的破坏形式主要表现为边坡后缘垂直的拉裂破坏和沿边坡中上部相对高度0.56处软弱夹层的剪切滑出破坏,边坡的破坏模式为拉裂-滑移-崩落式。本文提出的能量判识方法对识别边坡的破坏模式具有一定的指导意义。

Energy identification method for dynamic failure mode of bedding rock slope with soft strata

Based on the Hilbert-Huang transformation and marginal spectrum theory, large scale shaking table tests on rock slope with soft strata are performed. The energy method for dynamic failure mode identification of bedding rock slope with soft strata is studied according to the test results. The research results in this work show that the peak value and characteristic frequency of marginal spectrum can represent the dynamic damage development process in the rock slope clearly. In the bedding rock slope with soft strata, the dynamic damage first occurs on the slope shoulder, and then the damage location moves to the lower elevation with the increase of input seismic wave amplitude, and finally, the slope is sheared out at the location of upper soft strata. In the displacement monitoring, the displacement on the slope shoulder has fast change and then that at the upper location has quick change, that is to say, the displacement monitoring results are in agreement with the results of the marginal spectrum analysis. The dynamic damage degree near the slope face is more severe than that in the inner part of slope. The characteristic frequency in the lower-middle part is of great difference, indicating that the lower-middle part is a discontinuous zone of dynamic response for bedding rock slope with soft strata. The dynamic failure of bedding rock slope mainly includes vertical rip in the trailing edge of slope and the shearing out at the upper soft strata, that is, the dynamic failure mode of bedding slope with soft strata is a rip-slippage-avalanche mode. The proposed method will be a guide for identification of slope dynamic failure mode.