CYCLIC SHEAR BEHAVIOR OF SAND UNDER COMPLEX INITIAL CONSOLIDATED CONDITION

Various stress-controlled cyclic shear tests of saturated loose sand under various complex initial consolidation conditions and different patterns of vertical-and-torsional coupling shearing, which including cyclic triaxial shear loading, cyclic torsional shear loading, and both the bi-directional coupling cyclic shear loading, are conducted by using the soil static and dynamic universal triaxial and torsional shear apparatus. The cyclic shear behavir of the samples prepared by pluviation through air and consolidated at three different initial orientations of principal stress of 0°, 45°, and 90° in bi-directional coupling shearing tests and five different initial orientations of principal stress of 0°, 30°,45°, 60°and 90° in cyclic axial shearing tests. The purpose was to gain how and how much the initial consolidated stress condition effects the subsequent cyclic behavior of saturated loose sand while other conditions are not changed. All the tests show great influence of initial orientations of principal stress on the strength and deformation behavior of sand. When large pre-shear stress is imposed and no subsequent reversal stress on the application plane of dynamic stress, shearing deformation of loose sand results mainly from the one-directional accumulated deformation. When there is no initial shear stress or not large enough subsequent reverse stress exists on the application plane of dynamic stress, most of shearing deformation is of double-directional cyclic nature. The presentation will focus on experimental technique, observations and data.