上海地区第4层淤泥质黏土灵敏性试验与分析

Laboratory Studies on the Sensitivity of Layer No.4 Soft Clay in Shanghai

采用无侧限抗压强度试验、室内微型十字板剪切试验和原位十字板剪切试验对上海地区广泛分布的第4层淤泥质黏土的灵敏性进行了研究,并通过长达半年的触变恢复试验评价触变性对该软黏土灵敏性的作用.试验结果表明,由无侧限抗压强度试验得到的灵敏度约为十字板试验的1.8倍,手工重塑导致比十字板重塑更低的强度是造成这2种试验测得的灵敏度有较大差别的主要原因,因此不能直接采用原位十字板试验结果来评价该土层的结构性.长达半年的触变恢复试验结果表明触变性对上海第4层淤泥质黏土灵敏性的作用不可忽视,在采用传统的无侧限抗压强度试验所测得的灵敏度中至少有1/3是由于触变性造成的.

The sensitivity of layer No.4 soft clay in Shanghai was investigated by unconfined compression test,laboratory mini-vane shear test and field vane shear test.The thixotropy test lasting for about half one year was conducted to evaluate the effect of the thixotropy on the sensitivity for the soil.Results show that the sensitivities obtained by unconfined compression test is about 1.8 times that obtained by field vane shear test,smaller strength obtained by hand-remolding method than the vane-remolding method is the major reason that cause the huge difference between the results obtained by the two kinds of test.Therefore,the sensitivity measured by field vane shear test can＇ t be used directly to evaluate the sensitivity for the soil.The thixotropy test show the contribution of thixotropy on sensitivity of Shanghai soft clay can＇t be neglected and the thixotropy contributes at least 1/3 on the sensitivity that measured by unconfined compression test.