Temperature and strain-rate dependence of brittle rock deformation: Experimental study on Mohr-Coulomb's failure criterion and Byerlee's law for a low-porosity sandstone

For subsurface stress modeling, uniform failure and friction criteria are usually applied without consideration of in-situ temperatures and usage scenarios. We conducted thermotriaxial deformation tests on a low-porosity sandstone to investigate the temperature and strain-rate dependence of failure and friction parameters. Low temperature and strainrate dependences were found, which at 50 and 100 @C could be due to the kinematics of crack propagation and thermal cracking, respectively. A rate dependence of the strengths was observed, which strongly depends on the temperature and may be due to the water content of the microstructure. The results indicate that the uniform use of failure and friction criteria are not valid and may lead to an erroneous estimation of the subsurface stress state.