Abstract: Many factors, experimental conditions and complex coupled relations need to be considered in the multifield coupling of geomaterial. Therefore, it is much important to study the thermo-hydro-mechanical(THM) coupling problems using numerical simulation method. According to the continuum theory of mixture, a coupled model and the governing equations of the coupled problem of temperature, seepage, and stress field for geotechnical media are deduced. Strategy and methods to solve this mathematical model also are discussed. Based on the software MATLAB, the program of THM analysis is coded, in which Abaqus is embedded as a module in the iterative algorithm. Through two typical examples, the proposed THM program is verified; and the results show that this method is a very good analytical method and its efficiency is very good. And then the code of THM coupling model is applied to simulate the construction process of petroleum drilling and analysis of wellbore stability. The evolution law of temperature, pore pressure and stress field in surrounding rock are obtained. And the variations of drilling fluid temperature have significant influences on wellbore stability. The study has significant effects on the design and construction for underground oil and nuclear waste disposal.

Key words: geotechnical media, thermo-hydro-mechanical coupling, finite element program, secondary development, wellbore stability