One-Dimensional THM Coupling Model of Clay Layer Considering Non-Darcian Seepage and Thermo-Osmosis Under Semi-Thermally Insulated Boundary

Abstract

Clayey soils are widely present in energy and environmental geotechnical engineering projects, and their consolidation and thermal-diffusion behavior can remarkably influence the long-term stability of facilities. However, owing to the inherent complexity of thermo-hydro-mechanical (THM) coupled process, a thorough theoretical understanding into the underlying mechanisms remains insufficient. Consequently, a new THM-coupled model of saturated clay layer is developed, effectively capturing the interactions between nonlinear consolidation and heat transfer. Initially, the nonlinear consolidation process in current model accounts for the nonlinearity of seepage behavior and physical-mechanical properties. Of particular interest is the nonlinear seepage behavior under coupled thermo-mechanical loading, which is characterized by coupling non-Darcian seepage and thermo-osmosis within clays. Additionally, the heat transfer process incorporates the conduction, convection, and thermo-mechanical dispersion. To align with engineering reality, semi-drained and semi-thermally insulated boundaries are introduced during the derivation process. Numerical solutions are then obtained to delve into the impact of critical factors and the intrinsic relationship within THM-coupled process. The results reveal that both the consolidation and heat transfer processes experience retardation with consideration of nonlinear seepage. Moreover, the presence of a semi-thermally insulated boundary can significantly modify the temperature distribution and correspondingly affect the permeability of clays. In summary, the findings in the current study can provide a more reliable reference for engineering design of clay liner.