Fluid injection is widely used to enhance permeability in rock formations by creating or dilating transport pathways for resources such as oil, gas, heat, or CO2. The dynamic propagation of damage induced by fluid injection is governed by fluid flow, dynamic poroelastic deformation, mixed tensile and shear failure, and damage-induced antipermeability degradation. However, the transition from elastoplastic deformation to mixed-mode failure, as well as the induced dynamics, remains ambiguous. This study combines the dynamic Biot's poroelasticity and coupled Drucker-Prager plasticity, Grady-Kipp damage, and antipermeability degradation to simulate dynamic hydraulic fracturing. An explicit predictor-corrector scheme was employed to solve the dynamics of saturated porous media and identify the key factors controlling dynamic damage propagation. The proposed model was tested on soil column consolidation and rock hydraulic fracturing driven by a pre-existing crack, demonstrating good agreement between the numerical and experimental results. Simulation results indicate that damage zones facilitate preferential flow during fluid injection due to damage-induced degradation. The most extensive damage zone is observed under strong damage-permeability coupling. Shear plasticity, tensile damage, and induced seismicity are dominated by fracturing dynamics induced by fluid injection. Oscillations in the temporal-spatial evolution of damaged and plastic points, cumulated potency, and moment magnitude confirm the fracturing dynamics. Shorter injection times result in stronger dynamics and more significant damage propagation. The period of oscillations in cumulated potency increases with injection time while their amplitude gradually decreases due to energy release. These findings highlight injection-induced fracturing dynamics, offering novel insights into the dynamic propagation of damage coupled with matrix antipermeability degradation.

This study elucidates the findings of a computational investigation into the stimulation characteristics of natural reservoir systems enhanced by high-voltage electropulse-assisted fluid injection. The presented methodology delineates the comprehensive rock-fracturing process induced by electropulse and subsequent fluid injection, encompassing the discharge circuit, plasma channel formation, shockwave propagation, and hydro-mechanical response. A hydromechanical model incorporating an anisotropic plastic damage constitutive law, discrete fracture networks, and heterogeneous distribution is developed to represent the natural reservoir system. The results demonstrate that high-voltage electropulse effectively generates intricate fracture networks, significantly enhances the hydraulic properties of reservoir systems, and mitigates the adverse impact of ground stress on fracturing. The stimulationenhancing effect of electropulse is observed to intensify with increasing discharge voltage, with enhancements of 118.0%, 139.5%, and 169.0% corresponding to discharge voltages of 20 kV, 40 kV, and 60 kV, respectively. Additionally, a high-voltage electropulse with an initial voltage of U0 1/4 80 kV and capacitance C 1/4 5 mF has been shown to augment the efficiency of injection activation to approximately 201.1% compared to scenarios without electropulse. Under the influence of high-voltage electropulse, the fluid pressure distribution diverges from the conventional single direction of maximum stress, extending over larger areas. These innovative methods and findings hold potential implications for optimizing reservoir stimulation in geo-energy engineering. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).