中文摘要：

通过兰州、洛川、杨凌地区黄土在不同条件下的动扭剪三轴试验,研究了黄土阻尼比滞回圈形状变化的基本特性以及黄土阻尼比在不同固结压力、不同含水率条件下的变化规律。结果表明,黄土阻尼比滞回圈形状受动剪应变、含水率影响较明显;黄土阻尼比受一般的固结作用的影响并不大,但受含水率的影响较明显。根据含水率的不同,按照半对数坐标中的直线方程,分别给出了兰州、洛川、杨凌地区黄土阻尼比在不同固结压力下的拟合结果,并对拟合结果进行了对比分析;在此基础上,进一步对该三个地区黄土的阻尼比进行了汇总拟合,为西北相近地区黄土在中、大应变条件下的阻尼比取值提供了参考。

英文摘要：

Based on the torsion-shear tests of Lanzhou,Luochuan,Yangling loess under different water contents and consolidation stresses,the basic characteristics of loess＇hysteresis loop and the developing regularity of damping ratio are studied.The results show that the shapes of loess＇hysteresis loop are influenced obviously by the dynamic strain and water contents,and the loess＇damping ratio is influenced markedly by the water content,but not so obviously by the minor consolidation stress.According to different water contents,the fitting results（using the linear equation in semilog coordinate）of damping ratio values of Lanzhou,Luochuan,Yangling loess under different consolidation stresses are respectively given,as well as the comparative analysis of fitting results.Further more,the collective fitting results of damping ratio values of Lanzhou,Luochuan,Yangling loess are given,which offer the loess damping ratio reference in moderate-large stain for the close places in northwest of China.