Consolidation Tests Of A Saturated Soil Subjected To Different Heating-cooling Paths Of Hollow Cylindrical Specimens

The effect of temperature on mechanical behaviour of saturated clay soil is a hot topic in geotechnical engineering field in recent years, and it has a good application background in some field such as thermal energy storage, geothermal resources development, nuclear waste disposal, heating pipeline design and soft soil foundation reinforcement engineering. To the issue of thermal consolidation of saturated clay soil, especially the thermo-hydro-mechanical behaviour including internal heat source, international and domestic academics already have done some research in both laboratory test and analytical and numerical analysis. In the meanwhile, the existing research on the thermal consolidation has not yet formed a complete theoretical system, especially the thermal response of saturated clay soil under different temperature paths is still not clear enough. Therefore, this paper has carried out the thermal consolidation of saturated clay soil under different temperature paths systematically by using the self-developed thermal consolidation test device, the main work as follows:(1) The consolidation process under different stress state (50kPa, 100kPa,150kPa, 200kPa) and isothermal conditions (inner and outer heat source at room temperature 25℃) has been measured, including the pore water pressure dissipation process, the volumetric strain change process with time and the temperature fluctuation during the process.(2) The consolidation process under same (different) stress state and different (same) heating-cooling paths (single-stage paths:25℃â†'40℃â†'25℃,25℃â†'50℃â†' 25℃,25℃â†'60℃â†'25℃,25℃â†'75℃â†'25℃; multistage paths:25℃â†'40℃â†'50℃â†' 60℃â†'75℃â†'60℃â†'50℃â†'40℃â†'25℃; both inner and outer heat source at same temperature value) has been measured, including the pore water pressure dissipation process, the volumetric strain change process with time, water volume change of pressure chamber and temperature change duiring undrained heating and cooling process.(3) The consolidation process of single-stage heating-cooling paths has been compered with multistage heating-cooling paths under different stress state and isothermal conditions. Also the consolidation process of non-isothermal multistage paths (inner:25℃â†'50℃â†'50℃â†'75℃â†'75℃â†'25℃, outer:25℃â†'40℃â†'50℃â†' 60℃â†'75℃â†'25℃; inner:25℃â†'40℃â†'50℃â†'60℃â†'75℃â†'50℃â†'25℃, outer:25℃ â†' 50℃â†'50℃â†'75℃â†'75℃â†'50℃â†'25℃) has been compered with isothermal multistage paths.(4) The thermo-hydro-mechanical governing equation considering porous medium density, porosity and other material parameters changing with temperature and pressure has been deduced, which adopts the nonlinear elastic constitutive equation and heat sources, such as viscous dissipation. For one dimensional heat source situation, the evolution process of temperature, pore pressure and displacement has been analyzed.Based on the results of experiments in this paper, the pore water pressure and volumetric strain evolution laws of saturated clay soil under different temperature paths have been gained, and formulating the thermo-hydro-mechanical coupling model considering porous medium density, porosity and other material parameters changing with temperature and pressur, and analyzing the evolution process of temperature, pore pressure and displacement. Thesis results further develop and perfect the thermal consolidation theory of saturated clay soil, and also has a certain instruction value for some engineering applications involving soil temperature effect.