中文摘要：

利用GDS循环三轴试验系统,进行一系列不同细粒含量砂土的不排水动三轴试验,研究细粒含量对饱和砂土动弹性模量与阻尼比的影响。试验结果表明,砂土的动弹性模量随细粒含量的增加而减小,但当超过细粒含量的临界值30%后,变化趋势则相反;阻尼比随着细粒含量的增加呈现先增大后减小的趋势,其细粒含量的临界值也为30%。当细粒含量小于30%时,砂土的动力特性主要由粗粒决定,粗粒间形成的骨架孔隙比随细粒含量的增加而增大,相同应变水平下抵抗变形的能力随之减弱,从而使动弹性模量减小。同时,土颗粒间接触点的减少使应力波在土中传播速度变慢,使得土体对动荷载反应的滞后性增强,阻尼比随之增加;当细粒含量大于30%后,砂土的动力特性主要由细粒决定,细粒间孔隙比随着细粒含量的增加而减小,从而使砂土的动弹性模量与阻尼比呈现出相反的变化趋势。

英文摘要：

With the GDS dynamic triaxial system,undrained dynamic triaxial tests on the saturated sand of different fines contents were performed;and effects of fines content on the dynamic elastic modulus and damping ratio were analyzed.Results show that the dynamic elastic modulus of sand decreases with increasing of fines content;but the trend is reversed beyond the critical value of fines content of 30%.The damping ratio of sand firstly increases and then decreases with increasing fines content at the same critical value of fines content of 30%.When fines content is less than 30%,the dynamic characteristics of sand is determined mainly by the coarse grains;the skeleton void ratio between coarse grains increases with the increase of fines content;and the ability to resist deformation under the same strain level weakens so that the elastic modulus decreases.Meanwhile,the stress wave propagation speed slows down because of the reduction of contact points between soil particles,hysteresis quality of the soil dynamic load response strengthens and the damping ratio increases;when the fines content is greater than 30%,the dynamic characteristics of sand is determined mainly by the fine grains;the interfine void ratio decreases with increasing of fines content;so that the dynamic properties of sand shows a reverse trend.