Analytical solutions for coupled hydromechanical modeling of lateral earth pressures in unsaturated soils

Lateral earth pressures in unsaturated soils undergo variations with changes in suction (or pressure head) due to infiltration. The infiltration-induced alterations in the pressure head present a coupled hydromechanical problem, where interactions between solids and fluids influence the outcomes. However, existing analytical solutions for determining lateral earth pressures in unsaturated soils do not consider the effects of hydromechanical modeling. This paper presents analytical solutions for coupled hydromechanical modeling of lateral earth pressures in unsaturated soils. For this purpose, an analytical solution for coupled hydromechanical modeling of one-dimensional (vertical) infiltration is integrated into effective stress-based formulations for at-rest, active, and passive earth pressures of unsaturated soils. The solutions are presented for two cases: with and without a consequential drop in groundwater levels during infiltration. The results are verified by comparing them against those obtained from the finite difference method. The findings demonstrate significant differences between coupled and uncoupled results for pressure head and lateral earth pressures for fine-grained soils (characterized by small Gardner's coefficients) and during transient (short time) conditions. The comparison of analytical and numerical results was very close for both cases and thus illustrates that the Laplace Transform is an accurate and robust method for determining analytical solutions for this problem.