A damage constitutive model for cemented sandy gravel materials

Cemented sandy gravel is often used to enhance the foundation soil of engineering projects. This paper presents results of triaxial tests on cemented sandy gravel specimens. We compared 8 cemented specimens and 4 uncemented specimens. The strength, dilatancy, and stiffness behavior of both cemented and uncemented specimens are compared. The strength of cemented specimens is significantly greater than that of uncemented specimens, and the cemented specimens demonstrate pronounced expansion characteristics. The peak friction angle of the cemented specimen shows a linear relationship with the confining pressure: ψ = 68.1–18.2·lg(σ₃/pa). To quantify the structural strength of the cemented specimens, a structural damage parameter is introduced based on the differences in mechanical properties between the two materials. The structural damage parameter first increases and then decreases as shearing progresses, and a hump curve function is used to describe this behavior. In the frame of the generalized plasticity, a novel elastoplastic model is established, considering the structural parameter as a factor of the plastic modulus, loading vectors and plastic flow direction vectors. The calculated values fit well with the experimental results. The model can reflect the characteristics of cemented sandy gravel, in terms of stress softening, residual strength, and volumetric dilation. Finally, the model is used to evaluate the deformation of a sluice dam foundation after being enhanced with cemented sandy gravel. The results show that after treatment, both the settlement of the gate floor and the shear deformation of the waterstops can be reduced by more than 10%.