Determination of Multiple Thermo-Hydro-Mechanical Rock Properties in a Single Transient Experiment: Application to Shales

The experimental determination of the thermo-poro-elastic parameters of low-permeability geomaterials is difficult because particular care has to be taken with respect to the homogeneity of the pore pressure field during the tests. A new transient step loading procedure is presented for isotropic rock tests in drained and undrained conditions, and under thermal and mechanical loading. Two different proposed protocols allow to measure various drained and undrained parameters in one single test. The observed specimen deformations are analysed based on analytical solutions for the pore pressure diffusion (Braun et al. in Rock Mech Rock Eng 51:1361–1378, 2018), which enables to back calculate the material permeability. This provides more information in less time, compared to conventional monotonic loading experiments. A demonstration is given on the Callovo–Oxfordian claystone.