为研究水中高压电脉冲作用下页岩多条预制裂纹同步扩展应力干扰作用对裂纹扩展影响,通过裂纹扩展轨迹、扩展长度、平均宽度、偏转角度和裂纹间等效应力分布的变化规律,综合考虑裂纹夹角、裂纹数量、水平地应力差等因素对裂纹起裂、扩展...为研究水中高压电脉冲作用下页岩多条预制裂纹同步扩展应力干扰作用对裂纹扩展影响,通过裂纹扩展轨迹、扩展长度、平均宽度、偏转角度和裂纹间等效应力分布的变化规律,综合考虑裂纹夹角、裂纹数量、水平地应力差等因素对裂纹起裂、扩展的影响。采用真三轴高压脉冲水力压裂试验平台进行实验室压裂试验和扩展有限元法(extended finite element method, XFEM)数值模拟计算,利用PCAS(pore and cracks analysis system)裂隙分析软件分析裂纹几何形态特征。结果表明:水中高压电脉冲作用下,预制裂纹可沿径向及轴向起裂、扩展;径向双裂纹间夹角越大,缝间干扰作用越弱,裂纹扩展曲折程度越好,扩展效果越好;等夹角径向三裂纹扩展,中间裂纹受应力干扰、受抑制作用最大,不等夹角径向三裂纹扩展,远离中间裂纹的右侧裂纹受干扰最小,扩展效果最好;随着水平地应力差增加,裂纹间应力干扰作用增强,裂纹扩展效果逐渐减弱。研究成果可为分析水中高压电脉冲作用下页岩多预制裂纹扩展过程和规律提供一定的参考。展开更多
为研究高压电脉冲击穿过程对岩石破碎的影响,综合考虑击穿过程中岩石电导率和介电常数变化对电击穿作用的影响,利用COMSOL Multiphysics仿真软件建立了基于电场、传热场和固体力学场的多物理场耦合数值模型。结果表明:在本文参数条件下...为研究高压电脉冲击穿过程对岩石破碎的影响,综合考虑击穿过程中岩石电导率和介电常数变化对电击穿作用的影响,利用COMSOL Multiphysics仿真软件建立了基于电场、传热场和固体力学场的多物理场耦合数值模型。结果表明:在本文参数条件下,考虑电性参数(电导率和介电常数)变化带来的影响时,形成完整的电击穿通道的时间发生延迟,且在约0~170 ns时间内电性参数变化对应的最高温度不高于电性参数为定值对应的最高温度,在约170 ns之后则相反。电极间距不同,电脉冲形成的击穿通道形式不同,最大电流密度随电极间距增大而减小,击穿通道温度可达104 K。电压上升到达峰值的时间越长,岩石的破碎越充分,最大应力可达103 MPa。研究结论可为高压电脉冲破岩参数的选取提供参考和借鉴。To investigate the impact of high-voltage electrical pulse breakdown on rock fragmentation and changes in rock conductivity and dielectric constant during breakdown, a multi-physics coupling numerical model based on electric field, heat transfer field, and solid mechanics field was established using COMSOL Multiphysics simulation software. The results indicate that considering changes in electrical parameters (electrical conductivity and dielectric constant) delays the time required to form a complete electrical breakdown channel. Moreover, the maximum temperature corresponding to changes in electrical parameters does not exceed that corresponding to fixed values by more than 0~170 ns;however, after approximately 170 ns, this relationship reverses. The maximum current density decreases as electrode spacing increases while the temperature within the breakdown channel can reach up to 104 K. Longer voltage rise times result in complete rock fragmentation with maximum stress reaching up to 103 MPa. These research findings provide valuable guidance for selecting optimal.展开更多
文摘为研究水中高压电脉冲作用下页岩多条预制裂纹同步扩展应力干扰作用对裂纹扩展影响,通过裂纹扩展轨迹、扩展长度、平均宽度、偏转角度和裂纹间等效应力分布的变化规律,综合考虑裂纹夹角、裂纹数量、水平地应力差等因素对裂纹起裂、扩展的影响。采用真三轴高压脉冲水力压裂试验平台进行实验室压裂试验和扩展有限元法(extended finite element method, XFEM)数值模拟计算,利用PCAS(pore and cracks analysis system)裂隙分析软件分析裂纹几何形态特征。结果表明:水中高压电脉冲作用下,预制裂纹可沿径向及轴向起裂、扩展;径向双裂纹间夹角越大,缝间干扰作用越弱,裂纹扩展曲折程度越好,扩展效果越好;等夹角径向三裂纹扩展,中间裂纹受应力干扰、受抑制作用最大,不等夹角径向三裂纹扩展,远离中间裂纹的右侧裂纹受干扰最小,扩展效果最好;随着水平地应力差增加,裂纹间应力干扰作用增强,裂纹扩展效果逐渐减弱。研究成果可为分析水中高压电脉冲作用下页岩多预制裂纹扩展过程和规律提供一定的参考。
文摘为研究高压电脉冲击穿过程对岩石破碎的影响,综合考虑击穿过程中岩石电导率和介电常数变化对电击穿作用的影响,利用COMSOL Multiphysics仿真软件建立了基于电场、传热场和固体力学场的多物理场耦合数值模型。结果表明:在本文参数条件下,考虑电性参数(电导率和介电常数)变化带来的影响时,形成完整的电击穿通道的时间发生延迟,且在约0~170 ns时间内电性参数变化对应的最高温度不高于电性参数为定值对应的最高温度,在约170 ns之后则相反。电极间距不同,电脉冲形成的击穿通道形式不同,最大电流密度随电极间距增大而减小,击穿通道温度可达104 K。电压上升到达峰值的时间越长,岩石的破碎越充分,最大应力可达103 MPa。研究结论可为高压电脉冲破岩参数的选取提供参考和借鉴。To investigate the impact of high-voltage electrical pulse breakdown on rock fragmentation and changes in rock conductivity and dielectric constant during breakdown, a multi-physics coupling numerical model based on electric field, heat transfer field, and solid mechanics field was established using COMSOL Multiphysics simulation software. The results indicate that considering changes in electrical parameters (electrical conductivity and dielectric constant) delays the time required to form a complete electrical breakdown channel. Moreover, the maximum temperature corresponding to changes in electrical parameters does not exceed that corresponding to fixed values by more than 0~170 ns;however, after approximately 170 ns, this relationship reverses. The maximum current density decreases as electrode spacing increases while the temperature within the breakdown channel can reach up to 104 K. Longer voltage rise times result in complete rock fragmentation with maximum stress reaching up to 103 MPa. These research findings provide valuable guidance for selecting optimal.
基金Project(41972283) supported by the National Natural Science Foundation of ChinaProject(2023JJ306623) supported by the Hunan Provincial Natural Science Foundation of ChinaProject(2023ZZTS802) supported by the Fundamental Research Funds for the Central Universities,China。
