非饱和重塑低液限黏土体积变化特性试验研究

Experimental research on volume change of unsaturated remolded clay with low liquid-limit

采用GDS非饱和土三轴仪,在分别控制试样基质吸力和净平均应力条件下,对重塑非饱和低液限黏土的体积变化和含水率变化特性进行了试验研究。试验结果表明,试样的压缩指数密切地依赖于基质吸力,回弹指数也和基质吸力有一定的相关性,而且试样的收缩系数和土水特征曲线也密切地依赖于净平均应力。在给定的基质吸力条件下,随着净平均应力的增加孔隙比和含水率逐渐降低而饱和度逐渐增加,并在较高基质吸力情况下,试样含水率近似线性地依赖于净平均应力。在给定的净平均应力条件下,随着基质吸力的增加试样发生收缩。当试样基质吸力卸载到0时,试验结果表明在低净平均应力下试样发生膨胀,而在较高净平均应力下试样膨胀后发生坍塌。

The variation of volume and water content in unsaturated remolded clay specimens with low liquid-limit were studied by using GDS triaxial testing apparatus under the condition of controlled matrix suction and net mean stress in a predetermined stress path. The results show that the compression index and rebound coefficient are closely dependent on matrix suction, and the shrinkage index and the soil- water characteristic curve are closely related to the net mean stress. At a given level of matrix suction, the void ratio and water content of soil specimen decrease with the increase of net mean stress. The water content of soil specimen is linearly related to net mean stress when matrix suction is high. Under the condition of mean stress is given, the soil sample will shrink following the increase of matrix suction. When the matrix suction is unloaded to zero, the clay specimens will swell as the net mean stress is low. However, under higher net mean stress, the clay specimens will collapse after swelling.