饱和场地土动力特性试验研究

在工程实际中认为饱和度超过80 %即为饱和土，但在室内土工试验中制作的土样饱和度达95 %以上，后者经过试验测定，动力参数与前者实际上有一定差异。在50，100，200 kPa三种固结压力下分别对饱和度为95 %，92 %，88 %，83 %的饱和土样进行了循环单剪试验，得到了4种土样在3种固结压力下的最大动剪模量Gdmax和最大阻尼比Dmax，以及动剪模量比G/Gdmax-? 和阻尼比D/Dmax-? 归一化数值，并进行了对比分析。结果表明：在同一固结压力下，土样的Gdmax，Dmax，G/Gdmax随着饱和度增大有相对递减的趋势，而阻尼比D/Dmax数值随着饱和度加大而逐渐增加；随着固结压力的增大，4种土样的Gdmax，Dmax以及G/Gdmax-? (? 为动剪应变)数值上差异逐渐减小。最后对此种现象进行了讨论并分析其产生的原因。

Experimental study on dynamic characteristics of saturated soils

In project it is thought that the soil with saturation over 80% is called saturated soil. But the saturation of the sample produced in the indoor experiment reached over 95 %. In fact the dynamic parameter of the latter attained through the test is different from that of the former. In this paper, the cyclic simple shear tests of the saturated soil of saturation 95 %, 92 %, 88 % and 83 % were carried out under the consolidation pressure of 50 kPa, 100 kPa and 200 kPa respectively. Of four different sorts of soil sample under three different consolidation pressures, the maximum dynamic shear modulus Gdmax, the maximum damping ratio Dmax and the dynamic modulus ratio G/Gdmax-?, the damping ratio D/Dmax-? generalized curve were attained and analyzed comparatively. The results show that under the same consolidation pressure, the value of the Gdmax, Dmax, G/Gdmax shrink according to the growth of saturation; but the damping ratio D/Dmax, quite on the contrary, becomes larger with the raise of saturation, with the increasing of the consolidation pressure, the differences among the Gdmax, Dmax and G/Gdmax-? decrease gradually. Finally, this kind of phenomenon and its causes are discussed and analyzed.