剪切波速和含水率双指标评价黄土震陷

摘要

Based on experiments related to the dynamic characteristics of intact loess in Lanzhou, Gansu Province, in this paper, we investigate the prediction of the seismic subsidence of loess under earthquake load.We analyzed the relationship between shear-wave velocity and the seismic subsidence coefficient for different water-content intervals and the functions was polynomial-fitted.In a similar manner, we analyzed water content and the seismic subsidence coefficient at different shear-wave velocity intervals.By analyzing the relationship between shear-wave velocity and water content, we established a new method for evaluating the characteristics of the seismic subsidence of loess by associating shear-wave velocity with water content.We then used this method to predict the seismic subsidence of loess in the Yongdeng earthquake.The results indicate that the seismic subsidence coefficient increases with increasing water content at certain shear-wave velocity intervals and decreases with increasing shear-wave velocity at certain water-content intervals.We determined the absolute seismic subsidence ability to characterize the potential seismic subsidence ability that remains constant in different external loess conditions, as reflected by the shear-wave velocity.We also determined the absolute seismic subsidence coefficient to be proportional.We found water content to influence the release of the potential seismic subsidence ability.We used a case example to demonstrate the obvious practicality of this method.%为了研究地震荷载作用下黄土场地的震陷预测问题,以兰州黄土为研究对象来分析剪切波速和含水率与震陷系数的关系,并分别得出拟合函数关系.通过分析剪切波速和含水率在震陷过程中的内在联系,建立剪切波速和含水率双指标预测黄土震陷系数的方法,并依据该方法预测永登地震区黄土场地震陷量.研究结果表明:在一定的剪切波速区间内,震陷系数随着含水率的增加而增大;在一定的含水率区间内,震陷系数随着剪切波速的增加而减小.同时提出剪切波速可以反映黄土不因外部条件而变化的潜在震陷能力为绝对震陷能力的概念,相应的震陷系数称为绝对震陷系数,含水率影响潜在震陷能力的释放.通过震害实例计算验证剪切波速和含水率双指标预测方法的可行性.