Energy evolution and damage constitutive model of degraded limestone under the coupling effect of hydrodynamic-stress-chemical corrosion

The reservoir water level undergoes annual cyclical fluctuations, which leads to the state of hydrodynamic erosion of dry-wet cycles of the bedrock in the hydro-fluctuation belt. In addition, the self-weight of the overlying rock mass also worsens the strength of the bedrock. To study the deterioration law of the rock mass under the coupling of hydrodynamic-stress-chemical corrosion, degradation tests were conducted on limestone samples under the coupling of hydrodynamic-stress-chemical corrosion based on field investigations. The law of energy evolution of limestone under the coupling of hydrodynamic-stress-chemical corrosion was elucidated, and the damage constitutive model was proposed. The results show that: According to the energy rate-strain curve, the rock failure process can be divided into five stages: compaction of vulnerable zone, microfractures closure, elastic deformation, microfractures extension, and post-peak failure. With the increase of the degradation stress, part of the dissipative energy is released in advance, and the strain at which dissipated energy equals elastic energy gradually decreases. The sensitivity of total energy to degradation stress increases with the increase of dry-wet cycles. The coupling mechanism of hydrodynamic-stress-chemical corrosion was revealed. The damage constitutive model considering the deterioration of limestone in the compaction stage under the coupling of hydrodynamic-stress-chemical corrosion is proposed, which has higher prediction accuracy and can provide some theoretical guidance for disaster prediction and prevention in reservoir area.