A small strain constitutive model based on hardening soil model

A lot of on-site monitoring results show that the soil around many underground constructions is still in a state of small strain under working loads. It is important to consider the soil's small strain stiffness and stress-path dependency in analyzing interaction between soil and structure. Hardening soil model can define loading-unloading characteristics, however, it can not accurately simulate nonlinear modulus because unloading-reloading modulus is not associated with stress and strain level. In this paper, unloading-reloading modulus of hardening soil model is modified so that it is related to both stress and strain levels; and unloading shear strength and scant stiffness of lateral unloading stress path are also considered specially. Finally, the model results are compared with soil stress-path test results to prove the reasonableness of the model.