Abstract: The swelling stress field caused by the change in the moisture content in expansive soils will lead to an adverse effect on the behavior of retaining structures of tunnels and deep excavations. Based on the similarity of relevant theoretical expressions of thermal field and moisture field, the water absorbance induced expansion can be simulated by the temperature induced expansion in which the thermal expansion coefficient, α, and the thermal conductivity coefficient, λ, need to be firstly backanalyzed. A series of swelling force tests and surface wetting tests were conducted on the expansive soil samples taken from three typical strata in Hefei. The relationship between the swelling force and the initial moisture content and the empirical relations between the moisture content and the infiltrating time were established. Then the axisymmetric numerical model was established to simulate the swelling force test and the surface wetting test through thermalmechanical coupling analysis. Both the numerical simulations and the laboratory tests resulted in consistent results and the thermal expansion coefficient and thermal conductivity coefficient could be statistically back analyzed. The backanalyzed parameters could then be used in further analysis of tunneling and excavation engineering in expansive soils considering waterabsorbance process.

Key words: Expansive Soils, ThermalForce Coupling, Expansive Force, Thermal Expansion Coefficient