MODIFIED PLASTIC-WORK HARDENING PARAMETER AND FUNCTION INDEPENDENT OF STRESS PATH FOR SANDY SOIL

It is not simple to select the hardening parameter and function in the constitutive modeling of elastoplastic behavior for sandy soils due to the fact that there exists a clear effect of stress path on the deformation and strength of sandy soils.In order to better understand the above effect,a series of drained plane strain compression(PSC) tests along different stress paths are carried out on saturated dense specimens of sandy soil with precise stress and strain measurements.It is shown that all the strain increments(i.e.axial,lateral,shear and volumetric increments) are dependent on stress history and stress path.Therefore,the use of any quantity shown above as the hardening parameter that is independent of stress history and path in an elastoplastic model for sandy soil is not reasonable.Based on test results and precise data analysis,a unique modified plastic-work parameter and the related function,which are independent of stress path,are discovered.It is shown that using the modified plastic-work parameter and function as the hardening parameter and function that is independent of stress path in an elastoplastic model for sandy soil is consistent with theoretical assumption.By the comparison between the computational results and the experimental results,it can be seen that the effect of stress path on the deformation and strength of sandy soil could be successfully simulated by the elastoplastic model with the proposed modified plastic-work parameter and function.