Numerical simulations of hydro-mechanical coupling systems are of great importance in understanding the soil-water coupling problems generally encountered in geotechnical engineering. In this thesis, an innovative numerical procedure is developed to solve the hydro-mechanical coupling systems using Reproducing Kernel Particle Method (RKPM). Compared with the conventional Finite Element Method, RKPM, one type of meshfree methods, is free from the burden of mesh construction and can avoid deteriorated accuracy when large deformation occurs. To gain flexibility in numerical implementation, a sequential solution strategy is applied to solve the primary unknowns iteratively between the solid solver and fluid solver. Stability of the sequential scheme is ensured through the intro...[ Read more ]

Numerical simulations of hydro-mechanical coupling systems are of great importance in understanding the soil-water coupling problems generally encountered in geotechnical engineering. In this thesis, an innovative numerical procedure is developed to solve the hydro-mechanical coupling systems using Reproducing Kernel Particle Method (RKPM). Compared with the conventional Finite Element Method, RKPM, one type of meshfree methods, is free from the burden of mesh construction and can avoid deteriorated accuracy when large deformation occurs. To gain flexibility in numerical implementation, a sequential solution strategy is applied to solve the primary unknowns iteratively between the solid solver and fluid solver. Stability of the sequential scheme is ensured through the introduction of a relaxation term and is proved through stability analysis. Like conventional Finite Element Method without special treatment, spurious oscillations in pore fluid pressure distribution are frequently encountered under incompressible and impermeable conditions. An extra stabilization technique is therefore adopted to suppress the unphysical oscillations. The numerical procedure for solving the hydro-mechanical coupling systems is verified through simulations of one- and two-dimensional consolidation problems within elastic medium and comparisons with the analytical solutions. The effects of related influencing factors such as the support size and relaxation parameter on the convergence behavior are also investigated.

To better simulate the mechanical behaviors of dense and loose sands under complex loading conditions, a modified bounding surface hypoplasticity model is developed in this thesis. Modifications of the dilatancy relationship are proposed to make the model capable of simulating the cyclic mobility of dense sands and flow liquefaction of loose sands. The capability of the proposed soil model is demonstrated through comparisons between numerical simulations and laboratory tests of sands with different densities under undrained simple shear loading of various cyclic shear stress ratios.

Finally, both Mohr-Coulomb model and bounding surface hypoplasticity model are implemented in the numerical procedure to simulate a variety of boundary value problems, including plane strain biaxial compression test, strip footing problem and vertical slope problem. Simulations of strain localization under both drained and undrained conditions are highlighted. The regulatory effects of node refinement and the dilation parameter in the simulation of strain localization are also demonstrated. It is also shown that the modified bounding surface hypoplasticity model can adequately capture the different dilatancy behaviors of dense and loose sands during the shear band formation process.