A consolidation analysis method for an earth-rockfill dam based on the coupling of physical state, stress deformation, and seepage was established. In this method, a permeability coefficient model considering physical state and shear stress level was introduced, and it was integrated with Biot’s consolidation theory to simulate the coupling relationship. Taking the Nuozhadu high earth-rockfill dam as an example, a parameter back-analysis method using a neural network and evolutionary algorithm was applied to back-analyze the permeability coefficient model parameters of the core material based on observation data of pore water pressure in the dam. Then, consolidation numerical analyses were performed by using the back-analyzed parameters and the constant permeability measured in situ, respectively. The spatial and temporal distribution of pore water pressure calculated by the back-analyzed parameters coincided quite well with the monitoring data during construction and operation. However, the nume...

Nonlinear elastic model and elastoplastic model are two main kinds of constitutive models of soil, which are widely used in the numerical analyses of soil structure. In this study, Duncan and Chang's EB model and the generalized plasticity model proposed by Pastor, Zienkiewicz, and Chan was discussed and applied to describe the stress-strain relationship of rockfill materials. The two models were validated using the results of triaxial shear tests under different confining pressures. The comparisons between the fittings of models and test data showed that the modified generalized plasticity model is capable of simulating the mechanical behaviours of rockfill materials. The modified generalized plasticity model was implemented into a finite element code to carry out static analyses of a high earth-rockfill dam in China. Nonlinear elastic analyses were also performed with Duncan and Chang's EB model in the same program framework. The comparisons of FEM results andin situmonitoring data showed that the modified PZ-III model can give a better description of deformation of the earth-rockfill dam than Duncan and Chang’s EB model.

The second-order cone programming (SOCP) optimized FEM (named FEM-SOCP) is extended to solve the geotechnical problems involving nonassociated plasticity. When FEM-SOCP is used with strength reduction, FEM-SOCP generally can be more efficient because the shear strength reduction FEM (SSRFEM) is often used with a very large allowable maximum number of nonlinear iterations. The FEM-SOCP method cannot be directly applied to the geotechnical deformation analysis involving the nonassociated plasticity because only the geotechnical problem with associated plasticity can be cast into the SOCP problem. To remove the difficulty, a time-discrete method with automatic error control is proposed for the iterative scheme of approximating the nonassociated plastic problems with a series of associated plastic problems. Based on numerical investigations, the time step factor with the range of α = 0.1–0.4 generally may lead to an accurate solution with an optimized efficiency.

The parameters of the constitutive model, the creep model, and the wetting model of materials of the Nuozhadu high earth-rockfill dam were back-analyzed together based on field monitoring displacement data by employing an intelligent back-analysis method. In this method, an artificial neural network is used as a substitute for time-consuming finite element analysis, and an evolutionary algorithm is applied for both network training and parameter optimization. To avoid simultaneous back-analysis of many parameters, the model parameters of the three main dam materials are decoupled and back-analyzed separately in a particular order. Displacement back-analyses were performed at different stages of the construction period, with and without considering the creep and wetting deformations. Good agreement between the numerical results and the monitoring data was obtained for most observation points, which implies that the back-analysis method and decoupling method are effective for solving complex problems with multiple models and parameters. The comparison of calculation results based on different sets of back-analyzed model parameters indicates the necessity of taking the effects of creep and wetting into consideration in the numerical analyses of high earth-rockfill dams. With the resulting model parameters, the stress and deformation distributions at completion are predicted and analyzed.