INFLUENCES OF INITIAL STRESS CONDITIONS ON PLANE STRAIN BEHAVIORS OF SAND SPECIMENS

Plane strain compression tests (CD-test, σx=σx0=const.) were performed on Toyoura sand specimens measuring 9×8×5cm. The initial stress conditions of these specimens varied within the range of 100≤σz0≤300, 25≤σy0≤500 and σx0=100(kN/m2-unit). The following results were obtained: (1) The initial stress conditions are divided into three groups according to the specimens' dilatancy during initial stress loading; (2) Stress paths and stress strain relations under plane strain compression are classified into two or three groups corresponding to these groups; (3) Strength parameter is unique irrespective of the initial stress conditions.