Nonlinear Consolidation Analysis of Soft Soil Foundations Considering Large Strain and Non-Darcian Flow under Temperature Effects

The theory of thermal consolidation is widely applied in engineering projects such as ground source heat pumps, energy piles, and heating pipelines, which involve thermo-hydro-mechanical coupling in geomaterials. The physical and mechanical properties of soils are significantly affected by temperature changes. It has been shown that elevated temperatures result in increased soil settlement, and the continued use of traditional small-strain consolidation theories can lead to substantial errors in calculations. Moreover, soil permeability is altered by temperature variations, but most existing analyses are based on Darcy flow law, with the impact of non-Darcian flow on the thermal consolidation process often being neglected. In this study, the Hansbo’s flow model is utilized to account for the effects of temperature rise on the physical and mechanical properties of large-strain saturated soils. Governing equations for nonlinear consolidation and heat conduction are derived, and numerical solutions for excess pore water pressure and consolidation degree are presented. The validity and applicability of the theoretical model are verified under specific conditions. The impacts of large strain and non-Darcian flow on thermal consolidation are thoroughly investigated. It is demonstrated that temperature loading and non-Darcian flow both reduce the discrepancies in consolidation degrees between large- and small-strain models. The significant excess pore water pressure accumulation caused by non-Darcian effects is shown to be effectively mitigated under heating conditions. Additionally, the effect of temperature on promoting settlement is found to remain nearly constant under varying preconsolidation pressures. During multi-stage loading, the peak excess pore water pressure in the upper soil layer is consistently maintained at a low level, with heating further reducing it.