A material point finite element method for thermo-hydro-mechanical modeling in poro-elastic media with brittle fracturing

Abstract

<p>In this study, a powerful thermo-hydro-mechanical (THM) coupling solution scheme for saturated poro-elastic media involving brittle fracturing is developed. Under the local thermal non-equilibrium (LTNE) assumption, this scheme seamlessly combines the material point method (MPM) for accurately tracking solid-phase deformation and heat transport, and the Eulerian finite element method (FEM) for effectively capturing fluid flow and heat advection-diffusion behavior. The proposed approach circumvents the substantial challenges posed by large nonlinear equation systems with the monolithic solution scheme. The staggered solution process strategically separates each physical field through explicit or implicit integration. The characteristic-based method is used to stabilize advection-dominated heat flows for efficient numerical implementation. Furthermore, a fractional step approach is employed to decompose fluid velocity and pressure, thereby suppressing pore pressure oscillation on the linear background grid. The fracturing initiation and propagation are simulated by a rate-dependent phase field model. Through a series of quasi-static and transient simulations, the exceptional performance and promising potential of the proposed model in addressing THM fracturing problems in poro-elastic media is demonstrated.</p>