两种微倾黏土场地离心模型制备方法适用对比研究

A comparative study on the applicability of two centrifugal modelling methods for slightly inclined clay site

侧移是强震灾害中场地地基破坏的典型形式之一,而倾斜场地是侧移发生的一个重要条件。倾斜场地的制备是开展离心地震模型试验的基础而重要环节,针对两种微倾灵敏或软黏土场地的制备方法,通过常重力和60 g离心加速度下的T-bar试验,探讨抗剪强度的分布规律与空间均匀性,对比了两方法的适用性。试验结果表明:表面斜割法获得模型的抗剪强度随深度变化较均匀,常重力和离心加速度下与理论状态较好吻合;双箱变换-倾楔法在拆换的剪切箱内抗剪强度随深度发生了显著折减,且在顶部呈现回弯现象,常重力和离心加速度下与理论状态偏差较大,折减系数约为0.31;相比而言,前者更适于制备微倾灵敏黏土场地模型。研究方法和结论,对动力离心模型试验制备方法选取和进一步开展黏土场地侧移离心模型试验研究,提供了重要借鉴和理论支撑。

Lateral spreading is one of the typical damage of site foundation in strong earthquake disaster,andinclination of site is an important condition for lateral displacement.The preparation of inclined model is a basis and important part of centrifugal seismic test.Aiming at two preparation methods of slightly inclined sensitiveandsoftclay model,T-bar test has been done under constant gravity and 60 g centrifugal acceleration,the distribution law and spatial uniformity of shear strength are discussed,and the applicability of the two methods is compared.The experimental results show that the shear strength of the model obtained from the oblique cutting method changes uniformly with the depth,and it is in good agreement with the theoretical state under constant gravity and centrifugal acceleration;the shear strength of the model obtained from two box-wedge method shows significant reduction along the depth,and there is a back bending phenomenon at the top,under constant gravity and centrifugal acceleration,the deviation between the measured results and the theoretical state is large,and the reduction coefficient is about 0.31.In comparison,the former method is more suitable for the preparation of slightly inclined sensitiveclay site model.The research and conclusions provide important reference and theoretical support for the selection of preparation methods of dynamic centrifugal model test and the further study of lateral spreading centrifugal model test of clay site.