基于相场法的高压电脉冲压裂岩体裂缝扩展规律OA

[Objective]Rock fragmentation is a critical process in mining engineering,tunnel excavation,coalbed-gas exploitation and ultra-deep well construction.Conventional mechanical rock-breaking techniques suffer from severe bit abrasion,high construction cost,and low operational efficiency when applied to high-strength rock under complex geological conditions.As an emerging high-efficiency fragmentation technology,high-voltage electrical pulse(HVEP)rock breaking can induce rock failure via instantaneous energy release.Nevertheless,a compre-hensive quantitative evaluation framework for fracture initiation and rock mass damage evolution induced by HVEP has not been well established.This study aims to reveal the intrinsic mechanism of fracture initiation and pro-pagation in rock mass subjected to HVEP loads,clarify the temporal relationship between rock mass damage and fracture evolution driven by shock waves,and identify the effects of key discharge circuit parameters on rock-breaking performance.[Methods]Based on fracture mechanics and damage mechanics theories,a coupled phase-field fracture numerical model was constructed by integrating the RLC discharge circuit and the Weizel-Rompe plasma-arc impedance model.A tensile-compressive strain decomposition algorithm was adopted to distinguish tension-dominated fracture from pure compressive elastic deformation.Numerical simulations were carried out under typical working conditions:Discharge voltage 9-13 kV,capacitance 2-5 μF,circuit inductance 5-5 000 μH,and plasma-channel length 0.03-0.06 m.The phase-field variable was employed to quantitatively calculate initial fracture propagation length and damage area of the rock mass.The effects of shock wave characteristics,discharge voltage,capacitance,circuit inductance,and plasma-channel length on rock mass fracture behaviors were systematically analyzed.[Results]The simulation results demonstrated that rock mass damage evolution was strongly correlated with shock wave intensity and its rising rate.Damage did not equal fracture propagation,and damage initiation preceded macro-fracture initiation and served as a precursor of fracture formation.Higher shock wave intensity and faster rising rate accelerated fracture propagation,increased the degree of rock mass damage,and expanded the damage extent.Rock-breaking performance improved with the increase of discharge voltage and energy storage capacitance,whereas it degraded as plasma-channel length increased.Minor variations in circuit inductance had little influence on rock-breaking performance,while a substantial increase in inductance suppressed instantaneous energy release and weakened rock fragmentation.The waveform of displacement at the HVEP action point was similar to that of shock wave pressure.Influenced by rock material deformation and internal energy dissipation,the displacement response exhibited an obvious hysteresis relative to shock wave pressure.[Conclusion]The proposed coupled model realizes quantitative characterization of fracture growth and rock mass damage under HVEP loading.The findings can offer theoretical references for parameter selection and commissioning of HVEP rock-breaking equipment in practical rock-engineering applications.