ON STRESS-DILATANCY EQUATIONS OF SAND SUBJECTED TO CYCLIC LOADING
ON STRESS-DILATANCY EQUATIONS OF SAND SUBJECTED TO CYCLIC LOADING
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循环加载下砂土的应力-剪胀方程
DOI：
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发表时间：
1989
期刊：
影响因子：
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通讯作者：
F. Tatsuoka
中科院分区：
文献类型：
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作者：
T. Pradhan;F. Tatsuoka
摘要根据饱和丰浦砂在排水条件下的循环三轴试验和循环扭转单剪试验结果，研究了循环荷载作用下的应力-应变关系。从实验工作中发现，在每种测试方法中，应力比和孔隙率（应变增量比）之间存在唯一的关系，该关系与孔隙比和压力水平无关。实验还发现，体积应变增量与剪切应变增量之比（对于体积膨胀为正）所定义的剪切速率，在加载方向反向后，由于卸载而变为负值，并且在剪切应力的符号改变的时刻，剪切速率随着剪切而连续增加，而不表现出任何不连续的行为，随后它变为正值。因此，在相同的应力条件下，取决于剪切应变的方向，可能存在两种不同的剪切速率。四个不同的代表性的应力-应变关系的基础上（i）滑块理论，（ii）Rowe的理论，（iii）Roscoe的能量耗散理论，和（iv）泰勒的能量耗散理论，进行了修改，适用于循环加载条件下与反向加载方向。结果表明，经过这些修正后，某些理论能较好地模拟试验得到的排水循环条件下的应力-应变关系。最后，在应力平面上绘出了循环排水单剪等塑性势曲线。它是一个双塑性势函数，即两条不同的塑性势曲线通过任意给定的应力点，它们分别对应于两个不同的剪应变方向。
ABSTRACT Based on the results of a series of cyclic triaxial tests and cyclic torsional simple shear tests on saturated Toyoura sand performed under drained conditions, stress-dilatancy equations under cyclic loadings were studied. It has been found from the experimental work that in each of the testing methods a unique relationship between the stress ratio and the rate of dilatancy (strain increment ratio) exists which is independent of void ratio and pressure level. It has also been found experimentally that the rate of dilatancy, as defined as the rate of volumetric strain increment to shear strain increment (positive for volume expansion), becomes negative by unloading after the reversing of loading direction, and it increases continuously with shearing without showing any discontinuous behavior at the moment when the sign of shear stress changes, and subsequently it becomes positive. Thus, at the same stress condition, two different rates of dilatancy are possible to exist depending on the direction of shear straining. Four different representative stress-dilatancy relations based on (i) the sliding block theory, (ii) the Rowe’s theory, (iii) the Roscoe’s energy dissipation theory, and (iv) the Taylor’s energy dissipation theory, were modified to apply to cyclic loading conditions with reversed loading directions. It was found that after these modifications some of these theories can well simulate the stress-dilatancy relations under drained cyclic conditions obtained by the tests. Finally, curves of equal plastic potential in cyclic drained simple shear were portraied on a stress plane. It is a double plastic potential function in the sense that two different plastic potential curves are passing through any given stress point, which are for two different directions of shear-straining.