Numerical modelling of temperature effects on a rock mass in a controlled natural environment

This paper presents a method of modelling changes in temperatures and stresses within a tunnel wall as a response to an external thermal impulse. A rock face in the Josef Underground Laboratory, Czech Republic, was subjected to a thermal exposure for 48 days, showing in situ thermal propagation. The coupled thermal and mechanical response of the rock wall to increased temperatures demonstrates the role of the fracture network in controlling both heat propagation into the rock mass and the development of thermally induced strain. The joint network played a crucial role in the thermal flux, and it also defined its strain amplitude. Observations are made on the importance of correctly determining the thermal parameters and correctly assessing the local geomechanical settings. This work highlights the importance of defining the geomechanical settings of rock masses when analysing thermally-induced stress in natural conditions. Further, this work shows the necessity to evaluate extreme temperature scenarios to highlight potentially vulnerable slope sectors (e.g. due to wildfires).