Passive and active earth pressures in the presence of groundwater flow

This paper deals with the effect of seepage How on the lateral earth pressures acting on deep sheeted excavations in cohesionless soil. The computation of the passive and active earth pressures in the presence of hydraulic gradients is performed using the explicit finite difference method implemented in Fast Lagrangian Analysis of Continua (FLAC) code. The available effective passive earth pressure coefficients in the presence of upward seepage forces are given for both associative and non-associative material. The present solutions show that the soil dilation angle influences the effective passive earth pressures for large internal friction angle values of the soil. They also show that the effective passive pressures diminish with the hydraulic head loss. Good agreement is observed between the present results and those using an upper-bound approach in limit analysis for an associative material. For the active case, the effect of downward seepage forces on the active earth pressures is investigated. The numerical results show a significant increase in the effective active earth pressures due to a hydraulic head loss. It is also shown that the dilation angle influences the effective active earth pressures for large internal friction angle values.