Experimental and Numerical Investigation of Thermo-Mechanical Behavior of Shale

Shale can be a potential buffer for high-level radioactive nuclear wastes. Shales are highly heterogeneous materials and consist of different chemical compositions. Many researchers have experimentally characterized mechanical behavior of various shales at multiple scales in adiabatic condition. However, its mechanical performance at elevated temperature at micro/mano scale remains unknown. This presentation investigates the temperature dependency of mechanical and fracture properties of shale at different temperatures through experimental and numerical studies. We conducted nano-indentation test using TI 950 TriboIndenter equipped with a thermal stage, which allows to heat the samples to specific temperature. Mechanical properties of shale such as hardness, Young's modulus, and fracture toughness were measured and calculated. Initial results show that the hardness, Young's modulus, and fracture toughness reduce with the temperature increase from room temperature to 100◦C. X-Ray Diffraction (XRD) analysis was also performed on the flat surface of the shale sample to characterize the mineral compositions. Energy Dispersive X-Ray Spectroscopy (EDS) was used to obtain semi-quantitative elemental results within the area of interest. Additionally, we used ANSYS, a commercial software package to numerically investigate the mechanical performance of shale samples. Numerical results were validated against the experimental results confirming the simulation can be used to predict the shale deformation at the nano-scale.