STRESS HISTORY-DEPENDENT DEFORMATION CHARACTERISTICS OF DENSE SAND IN PLANE STRAIN

S. J. M. YASIN and FUMIO TATSUOKA,

ABSTRACT A series of drained stress path plane strain tests was performed on saturated dense specimens of Toyoura sand with precise stress and strain measurements. It is shown that all the strain increments (i.e. , axial, lateral, shear and volumetric) that occurred by loading between two stress states were dependent on the intermediate stress paths. It is suggested that the use of a strain quantity as the hardening parameter that is independent of stress history in an elasto-plastic model for sand may not be relevant. Based on the test results, one form of energy function is shown to be stress history-independent. This quantity is a state parameter, being a unique function of one form of stress parameter for different stress paths. How this function can be used as a stress history and stress path-independent hardening function in an elasto-plastic model briefly discussed. The effects of stress history and instantaneous stress path on the friction angles at the failure and residual states are negligible. The effects of stress path on stress-dilatancy relationships based on plastic strain increments are found to be small but noticeable.

Key words: elasto-plastic model, plane strain, sand, state parameter, stress-dilatancy relationship, stress path, stress- strain relationship (IGC: D6)