1 Background 1.1 Physical Properties of Unsaturated Infiltration 1.2 Governing Equation of Water Infiltration 1.3 Unsaturated Soil Slope Stability 2 Analytical Solution to Unsaturated Infiltration 2.1 Introduction 2.2 Analytical Solutions for Unsaturated Seepage 2.3 Boundary Effect 2.4 Conclusions 3 Physical Simulation of Rainfall Infiltration into Unsaturated Slopes 3.

1 Introduction 3.2 Model Testing of Rainfall Infiltration Soil Column 3.3 Laboratory Simulation of Rainfall-Induced Loess Slope Failure 3.4 Conclusions 4 Numerical Solution to Infiltration Equation 4.1 Introduction 4.2 Numerical Solution 37 4.3 An Improved Method for Non-Uniform Spatial Grid 4.4 Application of Chebyshev Spectral Method to Richards' Equation 4.

5 Conclusions 5 Improved Linear and Nonlinear Iterative Methods for Rainfall Infiltration Simulation 5.1 Introduction 5.2 Classical Linear Steady Iterative Method 5.3 Improved Jacobi Iterative Method with Two-Side Equilibration 5.4 A Chebyshev Semi-Iterative Method with Preconditioner 5.5 Application of Improved SOR Method in Unsaturated Flow 5.6 Improved Gauss-Seidel Method 5.7 Nonlinear Iterative Methods and Improvements 5.

8 Conclusions 6 Slope Stability Analysis Based on Analytical and Numerical Solution 6.1 Introduction 6.2 Numerical Application of Unsaturated Soil Slope Stability under Rainfall 6.3 Hydromechanical Coupling of Unsaturated Soil Slope Stability 6.4 Conclusions.