DEVELOPMENT OF SHEAR BAND AND PARTICLE CRUSHING OBSERVED IN IN-SITU LOADING TESTS ON A SEDIMENTED SAND

Abstract

Three loading tests of square footing (0.2, 0.3, 0.4m) were conducted in a pneumatic caisson being constructed 8.7m below the ground surface on a sandy layer containing cobbles, of which cohesive intercept was estimated to be 1kN/m² from triaxial compression tests and field direct tension tests. After the loading tests, visible shear bands were observed. A detailed examination of the shear bands by X-ray radiograph and magnified photograph reveals that the shear bands beneath the footing under high pressure were formed with densification by particle crushing, whereas the shear bands in passive zones under small pressure were loosen by positive dilatancy.