A constitutive model for load-deformation of sand-gravel materials in dam alluvium foundation and its engineering application

This paper investigates the mechanical properties of sand-gravel (SG) material in alluvium foundation, and further proposes a constitutive model suitable for load-deformation of this type of material. Taking silt content as an influencing factor, triaxial shear tests are carried out under different confining pressure conditions, and the influence of silt content on the material stress and strain characteristics are analyzed. Based on the test results, a new constitutive model for load-deformation of alluvium SG is proposed, which especially considered the strain softening and dilatancy characteristics. In order to simulate alluvium SG materials with varying silt contents consistently, the process for calculating the model parameters is quantified, and a regression relationship between the silt content and the model parameters is constructed. The model is integrated into the finite analysis code based on the modified Euler-Cauchy stress integral algorithm. Finally, taking Miaojiaba rockfill dam constructed on the alluvium foundation as an example, the proposed model is applied to calculate the dam and foundation stress and deformation. The difference between the simulated results and the monitoring data is compared to verify the model validity and practicability. The findings demonstrate that the model can accurately predict the deformation features of the alluvium foundation and that it performs calculations with greater precision than the traditional model.