A coupled thermal-hydraulic-mechanical application for subway tunnel

Subway tunnels and their surrounding geotechnical media are taken as an entirety, namely, tunnel-geomaterial system (TGS), and the stability and durability of the subway tunnels are subjected to the responses of the TGS to the thermal (T), hydraulic (H) and mechanical (M) loadings and their coupled effects. Modeling of the coupled THM processes that occur in the TGS are important for reliably assessing and predicting the performance of subway tunnels. Therefore, a numerical model of coupling the THM processes in the TGS is developed incorporating the equilibrium, motion, constitutive and compatibility equations. The proposed model considers full coupling between the thermal (temperature variation), hydraulic (water seepage), mechanical (subsidence) processes and changes in the material properties, such as stress-strain relation, viscosity, thermal conductivity, and hydraulic conductivity. The developed model is validated through comparisons of field tests, laboratory experiments and numerical simulations. Favorable agreement between the modeling results and the compared data verifies the capability of the developed model to well describe the THM behavior of subway tunnels in the TGS and their evolutions.