Elastoplastic model for cemented coarse-grained materials and its application

Until now, the engineers still doubt about whether the cemented coarse-grained soils can be used in permanent structures such as high rockfill dams. It is mainly due to the fact that the studies on the mechanical properties of the cemented coarse-grained soils are insufficient. At present, there is no widely accepted standard constitutive model for the cemented coarse-grained soils, so that the reliability of numerical simulation is greatly reduced. The indoor triaxial shear tests on cemented gravels are conducted under a large confining pressure range (7 confining pressures ranging from 100 to 3000 kPa). The test results show that the mechanical properties of the cemented gravels vary with different confining pressures. The nonlinear strength, dilatancy and strain softening can also be observed. It is found that the stress-strain relationship in triaxial stress paths can be described by the hump curve, and the dilatancy can be described by the Rowe's dilatancy equation. Based on the relationship between the tangent modulus and the plastic modulus in the generalized plasticity theory, the model is extended to the three-dimensional stress space. The test results and the others are used to verify the model, and the results show that the proposed model has good accuracy. The proposed model is easy to be numerically implemented. The model has been successfully applied in the elastic-plastic analysis of a cemented "high modulus zone" in a high concrete faced rockfill dam. The influences of the "high modulus zone" on the stress and deformation of the dam and the anti-seepage body are discussed, and the feasibility of using the cemented coarse-grained soils in high rockfill dams is evaluated. © 2019, Editorial Office of Chinese Journal of Geotechnical Engineering. All right reserved.