Revisiting Lateral Earth Pressures for Retaining Wall Backfilled with Unsaturated Soil

Abstract

The objective of this article is twofold: (a) reformulating the conventional expression of the suction stress and (b) reexamining the earth pressure in unsaturated backfills based on the newly-developed suction stress expression. Since its inception in the early twenty-first century, the concept of suction stress has been effectively used in many geotechnical stability analyses by combinedly employing the restricted version of the van-Genuchten’s soil–water-characteristics-curve (vG-SWCC) and Gardner’s one-parameter hydraulic conductivity function (HCF). Traditionally, the asymmetry parameter of the vG-SWCC model follows a strict relation with the pore spectrum number. An attempt has been made to relax this constraint and treat all the vG-SWCC model parameters independently. Furthermore, the pore spectrum-based Gardner’s HCF model is incorporated by adopting suitable numerical iterative schemes. By using the independent vG-SWCC parameters and Gardner’s one/two parameters dependent HCF model, the three states of earth pressures (at-rest, active, and passive) are extensively studied and critically scrutinized for hydrostatic as well as steady-state infiltration and evaporation. The independence of SWCC model parameters impacts the earth-pressure profiles to a significant extent, especially while soil dries up. On the other hand, one-parameter Gardner's model appears to be more effective and flexible than its two-parameter counterpart. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.