The problems of cost, environmental protection and efficiency of hard rock fragmentation in petroleum exploration, drilling and other projects need to be solved urgently. Electro-pulse-boring (EPB) technology has attracted attention due to its advantages of low rock breaking energy consumption, low wear and low time cost. However, there is still no more accurate description model for EPB and rock fragmentation, and the existing models have limited guidance on the parameter optimization of EPB tools. This paper introduces an electric breakdown model, which realizes the whole electric breakdown process under a single high-voltage pulse by coupling the five fields: circuit field, current field, breakdown field, heat transfer field and solid mechanical field. The multi physics model comprehensively considers the circuit structure parameters of the electric impulse generator (EIG), the initiation and development of electric breakdown, the dependence of electric breakdown strength and time, and the heterogeneity of rock. The model results found that the breakdown channel originates from the weak electric strength in the rock, and the development of the channel is highly dependent on the heterogeneity of the rock medium. The rock fragmentation process with a single pulse is accompanied by local electric fragmentation and hydroelectric fragmentation, When the pulse voltage rise time (PVRT) is greater than 500 ns, the hydroelectric fragmentation mode is dominant. The temperature and thermal stress values of the discharge channel are consistent with the previous studies results, and the temperature distribution at the electrode tip is the highest, which shows that the ablation problem of the electrode in EPB process can not be ignored. This model has the potential to establish the relationship between rock-breakingparameters and rock-breaking efficiency of EPB, and can provide a practical method for the development and parameter optimization of EPB and rock breaking tools.

石油勘探、钻井等工程中硬岩破碎的成本、环保和效率问题亟待解决。电脉冲钻孔（EPB）技术因其破岩能耗低、磨损小、时间成本低等优点而备受关注。然而，目前还没有更准确的EPB和岩石破碎描述模型，现有模型对EPB工具参数优化的指导作用有限。本文介绍了一种电击穿模型，通过耦合电路场、电流场、击穿场五个场，实现了单个高压脉冲下的整个电击穿过程。、传热场和固体力学场。多物理模型综合考虑了电脉冲发生器（EIG）的电路结构参数、电击穿的起始和发展、电击穿强度和时间的依赖性以及岩石的非均质性。模型结果发现，击穿通道源于岩石中的弱电强度，通道的发育高度依赖于岩石介质的非均质性。单脉冲岩石破碎过程伴随着局部电破碎和水电破碎，当脉冲电压上升时间（PVRT）大于500 ns时，水电破碎模式占主导地位。放电通道的温度和热应力值与前人研究结果一致，且电极尖端的温度分布最高，说明EPB工艺中电极的烧蚀问题不容忽视。该模型具有建立EPB破岩参数与破岩效率之间关系的潜力，可为EPB和破岩工具的开发和参数优化提供实用的方法。