Large deformation analysis of slopes and embankments

A robust and efficient numerical tool has been developed to evaluate the behaviour of slopes and embankments during failure and to determine the associated post-failure deformations. The large deformations accompanying failure in slopes can be captured by employing the 'Updated Lagrangian' formulation in a large deformation finite element analysis based on the Jaumann stress rate. Realistic behaviours of slopes during failure can be simulated if slope movements and changes in geometry are considered in the simulation. To enable the simulation of any possible progressive failure in slopes, an extended Mohr-Coulomb constitutive model, representing the strain softening behaviour of the slope material, is implemented in the program. Application of a strain softening model in finite element analysis is often accompanied by localisation of shear strains and lack of convergence. A remedy to these problems has been introduced and successfully implemented in the analysis of slopes. High gradient of strains and large deformations also result in distortions of finite element mesh and accumulation of errors in the solution. A proper numerical discretisation is required to reduce errors in the solution. 'h-adaptive' remeshing technique is employed to refine the finite element mesh around the area of large shear strains, thereby improving the accuracy and convergence of numerical solutions. This involves extensive programming in the area of mesh generation based on the 'Advancing Front Technique'. In addition, a proper error estimator needs to be defined in accordance with the problem of slope failure and pertinent variables should be mapped during remeshing. This study has provided a numerical tool that can be used to identify slopes with potential catastrophic failure and to investigate different factors affecting initiation of progressive failure. The validity of the proposed method and the efficiency of the numerical tool are demonstrated through simulation of a number of case studies on a range of slope failure problems, such as settlement of a highway embankment, failure of a test embankment during construction, and failure of a slope due to toe excavations. The predicted deformations are compared with the field measurements and reasonable agreements are obtained in all cases considered in this thesis