单轴试验条件下粘土的粘塑性与模拟计算

利用饱和、湿润、风干以及烘干的藤森粘土的单轴排水固结试验进行了粘土粘塑性研究。试验过程中采用计算机应变控制的控制式三轴仪来实现加载速率，可在不同加载阶段实现不同的恒应变率加载试验。试验结果表明：各种不同饱和度藤森粘土的粘塑性都表现为等时特性；经过一定时间的蠕变后，粘土弹性模量会有较大的提高，且藤森粘土所表现出的粘塑性与粘土含水量的大小无关。研究结果表明，粘土的粘塑性应力-应变特性可以采用非线性三要素模型进行较好的描述。

VISCOPLASTIC PROPERTIES OF CLAY UNDER UNIAXIAL TEST AND ITS SIMULATIVE CALCULATION

In order to study viscoplastic properties of clay,uniaxial compression tests are performed with computer-controlled triaxial apparatus on saturated,wet,air-dried,and oven-dried Japanese Pleistocene clay(Fujinomori clay:specific gravity Gs = 2.69,D50 = 0.017 mm,coefficient of uniformity Cu = 10,plastic limit IP = 33%,liquid limit IL = 62%).In the tests,axial(vertical) strain rate was changed stepwise for many times,and drained creep tests were performed for several times during monotonic loading at constant strain rate.Global unloading and reloading were also applied.Results of the tests on the Japanese Pleistocene clay with different water contents(different saturations) were presented.The results show that viscous properties of the Japanese Pleistocene clay with different water contents are significant in all the tests.Load rate effect(i.e.,the stress changes immediately after change in the strain rate occurred in the stress-strain curve) and creep deformation can be seen clearly in all the tests.The analytical test results show that:(1) viscous behaviour of Japanese Pleistocene clay does not appear due to the delayed dissipation of excess pore water pressure(not only saturated and wet but also air-dried and oven-dried specimens show significant viscous behaviour);(2) viscous properties of specimens with different saturations are similar(load rate effect and creep deformation were observed in all the specimens with different saturations);and(3) the stiffness of specimen with different saturations increases significantly after creep.In addition,a nonlinear three-component model is proposed,which can simulate well the viscous properties of clay.