Meso-statistical damage constitutive model and validation of coal under CO2 - load coupling

CO2 adsorption causes damage degradation to the coal body and thus reduces its stability, challenging the long-term safety of CO2 sequestration, and it is important to clarify the role of CO2 degradation and establish an ontological model. The damage mechanics theory and statistical theory were used to derive the calculation formula that can comprehensively reflect the total damage variables of the coal body under CO2 adsorption and load coupling, and focusing on the influence of the pressure-tight section, the fine statistical damage ontological equation of the coal body under the action of CO2 was established by segmentation, and the method of determining each parameter of the model was clarified. Finally, the parameters of the constitutive model were determined by CT scanning experiment system and MTS 816 experiment system, and the uniaxial compression experiments of coal body under different CO2 pressures were carried out by the self-developed gas-solid coupling experiment system to verify the rationality