A novel framework for nonlinear thermal elastic-viscoplastic (TEVP) constitutive relationships was proposed in this study, incorporating three distinct thermoplasticity mechanisms. These four TEVP formulations, combined with an existing TEVP constitutive equation presented in the companion paper, were integrated into a coupled consolidation and heat transfer (CHT) numerical model. The CHT model accounts for large strain, soil selfweight, creep strains, thermal-induced strains, the relative velocity of fluid and solid phases, varying hydraulic conductivity and compressibility during consolidation process, time-dependent loading, and heat transfer, including thermal conduction, thermo-mechanical dispersion, and advection. The performance of CHT model, incorporating different TEVP constitutive equations, was evaluated through comparing the simulation results with measurements from laboratory oedometer tests. Simulation results, including settlement, excess pore pressure and temperature profiles, showed good agreement with the experimental data. All four TEVP constitutive relationships produced identical results for the consolidation behavior of soil that in the oedometer tests. The TEVP constitutive equations may not have a significant effect on the heat transfer in soil layers because of the identical performance on simulating soil compression. The CHT model, incorporating the four TEVP constitutive equations, was then used to investigate the long-term consolidation and heat transfer behavior of a four layer soil stratum under seasonally cyclic thermal loading in a field test, with excellent agreement observed between simulated results and measured data.

A numerical model that accounts for fully coupled long-term large strain consolidation and heat transfer provides a more realistic analysis for various applications, including geothermal energy storage and extraction, buried power cables, waste disposal, groundwater tracers, and landfills. Despite its importance, existing models rarely simulate fully coupled large-strain long-term consolidation and heat transfer effectively. To address this research gap, this study presents a numerical model, called Consolidation and Heat Transfer (i.e., CHT), designed for one-dimensional (1D) coupled large-strain consolidation and heat transfer in layered soils, with the added capability to account for thermal creep. The model employs a piecewise-linear approach for the coupled long-term finite strain consolidation and heat transfer processes. The consolidation algorithm extends the functionality of the CS-EVP code by incorporating thermally induced strains. The heat transfer algorithm accounts for conduction, thermomechanical dispersion, and advection, assuming local thermal equilibrium between fluid and solid phases. Heat transfer is consistent with the spatial and temporal variation of void ratio and seepage velocity in the long-term consolidating layer. This paper details the development of the CHT model, presents verification checks against existing numerical solutions, and demonstrates its performance through several simulations. These simulations illustrate the effects of seepage velocity, thermal boundary conditions, and layered soil configurations on the coupled heat transfer and consolidation behavior of saturated compressible soils.

This study focuses on predicting the impacts of a heating-cooling cycle on the pullout capacity of energy piles installed through a soft clay layer. Geotechnical centrifuge physical modeling was used to evaluate temperature, pore water pressure, volume change, and undrained shear strength profiles in clay layers surrounding energy piles heated to different maximum temperatures to understand their impacts on the pile pullout capacity. During centrifugation at 50 g, piles were jacked-in at a constant rate of penetration into a kaolinite clay layer consolidated from a slurry in a cylindrical aluminum container, heated to a target temperature after stabilization of installation effects, cooled after completion of thermal consolidation requiring up to 30 hours (1250 days in prototype scale), then pulled out at a constant rate. T-bar penetration tests were performed after the heatingcooling cycle to assess differences in clay undrained shear strength from a baseline test. The pullout capacity of an energy pile heated to 80 degrees C then cooled to ambient temperature was 109 % greater than the capacity in the baseline test at 23 degrees C, representing a substantial improvement. The average undrained shear strength measured with the T-bar at a distance of 3.5 pile diameters from the pile heated to 80 degrees C was 60 % greater than at 23 degrees C but followed the same trend as pile capacity with temperature. An empirical model for the pullout capacity was developed by combining predictions of soil temperature, thermal excess pore water pressure, thermal volumetric strain, and undrained shear strength for different maximum pile temperatures. The empirical model predictions matched well with measured pullout capacities.

Prefabricated vertical drains combined with heating is a new approach to improving the mechanical properties of soft clay foundations. Rising temperatures cause the formation of concentric and radially aligned soil regions with distinct heterogeneous characteristics. This results in incomplete contact between adjacent soil layers, with the water in the interstices impeding heat transfer and manifesting as a thermal resistance effect. Based on the theory of thermo-hydro-mechanical coupling, a two-dimensional dual-zone axisymmetric marine soft soil model improved by a prefabricated vertical thermo-drain has been established. A generalized incomplete thermal contact model has been proposed to describe the thermal resistance effect at the interface of concentric soil regions. The effectiveness of the numerical solution presented in this paper is verified by comparison with semi-analytical solutions and model experiments. The thermal consolidation characteristics of concentric regions of soil at various depths under different thermal contact models were discussed by comprehensively analyzing the effects of different parameters under various thermal contact models. The outcomes indicate that the generalized incomplete thermal contact model provides a more accurate description of the radial thermal consolidation characteristics of concentric regions of soil. The influence of the thermal conductivity coefficient on the consolidation characteristics of the concentric regions soil is related to the thermal resistance effect.

Laminar flow phenomena may occur when pore water flows at low velocities across the interfaces between soils of different properties, thus causing flow contact resistance. To explore the impacts of interfacial flow contact resistance and rheological characteristics on the thermal consolidation process of layered viscoelastic saturated soil foundation featuring semi-permeable boundaries. This paper established a new thermal consolidation model by introducing a fractional order derivative model, Hagen-Poiseuille law and time-dependent loadings. The semi-analytical solutions for the proposed thermal consolidation model are derived through the Laplace transform and its inverse transform. The reliability and correctness of the solutions are verified with the experimental data in literatures. The influence of constitutive parameters, flow contact resistance model parameters on thermal consolidation process and the interfacial flow contact resistance on foundation settlement, is further explored. The results indicate that the impact of the constitutive parameters and permeability coefficient on the thermal consolidation of viscoelastic saturated soil is related to the flow contact resistance. The enhanced flow contact resistance effect leads to a significant increase in pore water pressure and displacement during the consolidation process.

This paper focuses on investigating the one-dimensional thermal consolidation of unsaturated soil. Through the utilization of the Laplace transformation, decoupling method, and inverse Laplace transformation, the semianalytical solutions for excess pore pressures and ground settlement are deduced, particularly in the context of a single-sided semi-permeable boundary. To further investigate the thermal consolidation characteristics in unsaturated soils, numerical modeling is employed, encompassing both single-sided semi-permeable and symmetric semi-permeable boundaries. Consequently, the proposed solution is subjected to a rigorous comparison and analysis against existing published solutions and numerical results, thereby establishing a remarkable degree of consistency. A comprehensive parametric analysis is conducted to discuss the thermal consolidation behavior, revealing the temperature effect can lead to negative pore-water pressure at the end of dissipation and a rebound phenomenon of the ground settlement. Notably, the variation in temperature affects the final settlement of the soil. Furthermore, alterations in top permeability parameters influence the dissipation of excess pore pressures within specific depth ranges, wherein the influence depth increases as the boundary permeability strengthens. Of particular interest is the applicability of the current solution, which accommodates the one-dimensional thermal consolidation model for unsaturated soils characterized by varying permeability topsides and depth-dependent linear initial conditions.

Due to the presence of tiny gaps at the interface of two layers of saturated soil, water seepage occurs at a slower rate within these gaps, resulting in laminar flow at the interface. Based on the Hagen-Poiseuille law, a general imperfect flow contact model was established for layered saturated soil interfaces by introducing the flow contact transfer coefficient R omega and the flow partition coefficient eta omega. The investigation focused on the thermal consolidation behavior of layered saturated soil foundations under variable loadings considering the flow contact resistance effect at the interface. By employing the Laplace transform and its inverse transform, a semi-analytical solution for the thermal consolidation of layered saturated soil foundations was derived. In the context of a two-layer soil system, the effects of R omega, eta omega, and permeability coefficient k on the consolidation process were examined. The obtained results were then compared with three other interfacial contact models, thereby confirming the rationality of the presented model. The study findings revealed that the flow contact resistance effect leads to a clear jump in the pore water pressure. Furthermore, an increase in R omega and a decrease in eta omega were found to significantly enhance displacement and pore water pressure, while having minimal impact on the temperature increment. These insights contribute to a more comprehensive understanding of the thermal consolidation behavior of layered saturated soil foundations and underscore the significance of accounting for the flow contact resistance effect in such analyses.