Staged development of finite element methods for stability of unsaturated soil slopes

The slope failure is a kind of frequently-encountered geotechnical disaster. Many cases of slope failure are induced by the rapid transition between the saturated state and the unsaturated state of soil due to the heavy rainfall or sudden water drawdown. The slope failure induced by these changes can be adequately interpreted by the shear strength theory of unsaturated soil. Three distinct stages are systematically introduced to clearly illustrate the staged development of finite element methods for stability of unsaturated soil slopes, that is, time-independent qualitative analysis, time-dependent analysis with decoupled pore fluid flow and deformation, and fully coupled solid-fluid analysis.