掺砾黏土样的大型三轴流变特性试验研究

高心墙堆石坝的砾质土筑坝材料含有较大颗粒，又含有大比例的黏性土，渗透系数较低，试验需要用大尺寸的仪器。大尺寸试验排水、饱和困难、试验周期长、难度大，一直是试验工作的难点，在砾质土试样中预留砂芯加速排水饱和的方法可以有效地解决该问题。对掺砾黏土样进行了大型三轴流变试验，通过实测蠕变量和蠕变模型参数对掺砾后黏土样的流变特性进行了分析。研究结果表明，掺砾黏土样的蠕变量与时间关系呈现较好的幂函数关系，采用长江科学院蠕变模型可准确地描述其流变特性；在相同饱和状态下掺砾样的蠕变量和蠕变模型参数指标较低，说明掺砾起到了改善土样工程性状的功能；在均为土样或者掺砾样条件下非饱和状态的蠕变指标明显低于饱和状态下的蠕变指标，说明预留砂芯加速排水的方法起到了明显的作用，促进了试样的充分饱和。

Test study of large-scale triaxial rheological property of clay materials with gravel

The large-scale triaxial apparatus is indispensable in the experimental application of soil materials with gravel for which have much larger grains in high core rockfill dams. Also the great percentage of clay has increased the level of challenge in the experimental work because of low permeability coefficient, difficulties of saturated and consolidation, long test period and so on for large scale specimens. To solve these practical problems effectively, sand cores has been reserved to accelerate saturation and consolidation in this paper’s tests. Analyses have been conducted on the creep strain and the creep model parameters of clay material with gravel tested by large-scale rheological triaxial apparatus. The results indicate that the rational power function relationship between creep strain and load time could exactly be described by the creep model of Yangtze River Scientific Research Institute. It is also revealed that the clay materials with gravel have smaller creep strain and lower model parameter indexes than the same materials without gravel. Consequently, mixing appropriate amount of gravel into clay soil could improve the engineering characteristics. The creep indexes of unsaturated materials are obviously lower than them of saturated materials in conditions of clay or clay with gravels. This fully shows that the sand cores reserved to accelerate draining play an very apparent role in the test process.