CONSTANT PRESSURE AND CONSTANT VOLUME DIRECT SHEAR TESTS ON REINFORCED SAND

JIN-YANG QIU, FUMIO TATSUOKA and TARO UCHIMURA

ABSTRACT: In order to investigate the deformation and strength characteristics of reinforced sand, a series of relatively large-in- scale direct shear tests was performed. Phosphor bronze strips and sheets with different configurations were used as reinforcement to study the effects of the shape and dimensions of reinforcement. Constant pressure tests and constant volume tests were conducted with different forms of reinforcement and different values of stiffness, surface area, spatial dispersion and surface friction. Test results show that for a given amount of reinforcement material, the reinforcing efficiency is higher with reinforcement having a larger surface area, a rougher surface texture and a larger degree of dispersion. The dilatancy at the residual state depends on the reinforcement property and geometry, and it is larger in more effectively reinforced sand with a larger shear zone. More dilative characteristics of reinforced soil results in larger shear strength under constant volume conditions at large strains.

Key words: (constant-pressure test), (constant-volume test), dilatancy, direct shear test, reinforced soil, shear band, shear strength (IGC: D6)