A MODIFIED DUNCAN-CHANG E-B MODEL WITH PARTICLE BREAKAGE FOR CALCAREOUS SAND

Particles breakage under normal stress levels distinguishes calcareous sand from other sands and is one of the important properties of calcareous sands. Due to particle breakage, the mechanical behavior of calcareous sands cannot be well simulated using the traditional constitutive models. Therefore, based on the Duncan-Chang E-B model, this paper proposes a constitutive model that can be used for calcareous sands by considering particle breakage. The specific method is as follows. Firstly, this paper uses the relative breakage B_r proposed by Hardin to measure the degree of particle breakage. Moreover, the influence of particle breakage on Duncan-Chang model parameters including internal friction angle, secant modulus E₅₀ and bulk modulus B is obtained. Then, the relative breakage B_r, which cannot be directly determined in each state, is related to the determinable stress-strain state by the relationship between particle breakage and input energy. Finally, a modified Duncan-Chang E-B model for calcareous sand considering particle breakage is proposed in this paper. In order to verify the accuracy and applicability of the model, this model is used to simulate the triaxial drainage behavior of calcareous sands with four particle sizes. It is shown that the simulation results agree well with the experimental ones, and the modified model is significantly better than the conventional Duncan-Chang E-B model in the case of large particle breakage.