Dynamic Breakage Characteristics of Shale with Different Bedding Angles under the Different Ambient Temperatures

Abstract

The dynamic mechanical experiments were carried out on shales with the different bedding angles (θ = 0°, 30°, 45°, 60°, 90°) using the 50 mm split Hopkinson pressure bar (SHPB) test system with the thermo-mechanical coupling equipment. Firstly, the dynamic parameter of shales, such as the stress–strain curve, peak stress, peak strain, dynamic elastic modulus, and energy partition were acquired. The failure modes of shale samples were obtained by sorting out the fragments after impact tests. Secondly, the fracture roughness of shale was obtained using the 3D profile scanner. The experimental results revealed that the shale with different bedding angle has different critical temperature, which is based on the relative transition temperature of dynamic mechanical parameters. The dynamic mechanical properties of shale vary greatly before and after the critical temperature. The absorption energy is positively correlated with the crushing degree, the dynamic compressive strength is positively correlated with the fracture roughness, and the failure degree of shale samples is closely related to the temperature. Additionally, the dynamic mechanical properties of the shales with 0° and 90° bedding angles are obviously different from the shales with 30°, 45° and 60° bedding angles. The related findings could provide significant theoretical support for exploitation of shale gas.