One-Way Cyclic Triaxial Behavior of Saturated Clay: Comparison between Constant and Variable Confining Pressure

The one-way cyclic triaxial test has been recognized as a useful tool for solving many engineering problems, such as the prediction of deformation in subsoils under traffic loading. Most studies of the one-way cyclic behavior of soils are performed in triaxial tests with constant confining pressure (CCP), which can apply cyclic compressive deviatoric stress only. However, the real stress field in subsoils under traffic loading includes varying normal stresses in three directions. Therefore, it is more desirable to simulate the in situ loading conditions induced by passing vehicles through a combination of the varying deviatoric stress and varying confining pressure. Recognizing this, two series of one-way cyclic triaxial tests on remolded saturated clay were conducted in this study; one in undrained conditions and the other in partially drained conditions. In each series, both tests with the CCP and variable confining pressure (VCP) were carried out. Comparisons between the results of the VCP and CCP tests show that the VCP plays an important role in the one-way cyclic behavior of saturated clay, in terms of excess pore-water pressure, permanent volumetric strain, and permanent axial strain. Specifically, in partially drained conditions VCP tests deliver much larger permanent axial strain than CCP tests, indicating that the conventional CCP tests may underestimate the settlement of subsoils induced by traffic loading. DOI: 10.1061/(ASCE)GT.1943-5606.0000760. (C) 2013 American Society of Civil Engineers.