Study on the statistical damage constitutive model and experiment of hot dry rock cyclic heating-cooling based on the octahedral strength criterion

Understanding the alteration in rock mechanics post heating and cyclic cooling is crucial for hot dry rock geothermal energy extraction projects. Against this backdrop, a constitutive model adept at delineating rock behavior under cyclic heating-cooling scenarios is introduced. The model presumes rock micro-element failure to adhere to the Weibull distribution and is constructed upon an octahedral shear stress strength criterion, integrating thermal and mechanical damage statistics. Model parameters were derived via the peak point method. The model's validity was ascertained through heating-cycle cooling-uniaxial compression experiments on hot dry granite. The experimental outcomes substantiate the model's efficacy. Within the model, the parameters r and S are not only of practical physical significance but also serve as indices to quantify rock brittleness and peak strength, respectively. The findings of this study are expected to contribute theoretical insights for deep geotechnical engineering applications, including geothermal resource extraction.