A thermo-mechanical phase-field model for mixed-mode fracture and its application in rock-like materials

Thermally induced fracture is a common phenomenon for concrete and rock-like materials, which presents a significant challenge to numerical modelling. In this work, a thermo-mechanical model for mixed-mode fracture based on phase-field method is proposed. This approach overcomes the difficulties of modelling the thermally induced cracking process when it comes to complex fracture patterns. To simulate different failure modes in thermo-mechanical conditions, the model's constitutive expression includes a unified failure criterion that takes into account both tensile and shear strengths. The proposed formulation provides a length scale insensitive response for brittle materials such as rocks, although other prevalent phase-field theories for purely mechanical fracture can also be involved. The computational results of the representative examples for rock-like materials are highly consistent with prior findings. It demonstrates that the presented model can effectively reproduce the thermally induced cracking process for various cracking patterns, such as tensile, shear, and tensile-shear fractures, indicating the method's remarkable capabilities for further research.