Modelling of drained and undrained cyclic shear behavior of sand

摘要

An elasto-plastic constitutive model capable of simulating both monotonic and cyclic drainedrnand undrained torsional shear behavior of sand is presented. The generalized hyperbolic equation (GHE) hasrnbeen employed to model the drained monotonic behavior of sand. Then the cyclic shear behavior is modelledrnby combining the GHE with extended Masing”s rules considering the hardening behavior of sand duringrndrained cyclic loadings and the damage to soil skeleton at large stress levels. A modified stress-dilatancy relationshiprnthat relates the ratio of plastic strain increments (-dε_(vol)~p/dγ_(zθ)~p to stress ratio (τ_(zθ)/p’) is proposed tornsimulate the volumetric behavior of sand. To model the undrained cyclic shear behavior, it is assumed that therntotal volumetric strain increment is equal to zero. The proposed model is calibrated by means of the results ofrna series of drained and undrained cyclic torsional shear tests on hollow cylindrical Toyoura sand specimens.rnComparison with experiment data suggests that the propose model can reasonably simulate the stress-strainrnrelationship and volumetric behavior of sand subjected to drained cyclic loadings and the generation of excessrnpore water pressure and stress-strain relationship during undrained cyclic loading.