The Utilization of a Coupled Electro-Thermal-Mechanical Model of High-Voltage Electric Pulse on Rock Fracture

Abstract

Our research proposes a unique coupled electro-thermal-mechanical model that takes electric breakdown and heterogeneity into account to show the mechanism of rock fracturing under high-voltage electropulses. Using finite element numerical software, the process of high voltage electrical pulse injection into the rock interior for breakdown is described, and the formation law of plasma channels during the electrical breakdown process is comprehensively analyzed in conjunction with the conductor particles present within the rock. On the basis of electrical, thermal, and mechanical theories, a coupled multi-physical field numerical model of rock failure under the action of high-voltage electrical pulses is developed, and a random distribution model is utilized to simulate the potential occurrence of conductor particles in the rock. Innovative numerical model indicates plasma channel creation in the rock-crushing process. Prior to the formation of the plasma channel, the temperature and stress are approximately 103 k and 10−2 MPa, respectively. Once the plasma channel is formed, the temperature and stress increase abruptly in a short time, with the temperature reaching 104 k and the stress reaching 103 MPa or higher. In addition, it is revealed that the breakdown field strength is the essential factor in plasma channel creation. The heterogeneity of the particles within the rock and the fluctuation in electrode settings are also significant variables influencing the creation of channels. The presented model contributes to a better understanding of the mechanism of rock fragmentation during high-voltage electrical pulses, which has substantial implications for oil exploration and mineral extraction.

Formation of plasma channel under high-voltage electric pulse and simulation of rock-breaking process

“…In addition, Zhu et al [22] mentioned in the literature that after the formation of the plasma channel, the energy in the high-voltage electric pulse was released into the plasma channel, which started to be heated, and then the plasma channel expanded thermally, generating a shock stress wave that acted on the surrounding rock. Ultimately, it causes 'damage' inside the rock, and the authores have the same conclusion in previous paper [25]. Therefore, the analysis of the mechanism of high-voltage electric pulse rock breaking should be divided into before the formation of the plasma channel and after the formation of the plasma channel.…”

Chemical Corrosion-Water-Confining Pressure Coupling Damage Constitutive Model of Rock Based on the SMP Strength Criterion

“…The integration of a constitutive model holds utmost importance in the framework of rock mechanics’ strength theory. Significant progress and achievements have been made in the theory of rock damage by researchers both domestically and internationally [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. Rocks typically exhibit robust coupling properties as a result of the interplay between geological processes and intricate natural surroundings over extended periods.…”

“…The integration of a constitutive model holds utmost importance in the framework of rock mechanics' strength theory. Significant progress and achievements have been made in the theory of rock damage by researchers both domestically and internationally [3][4][5][6][7][8][9][10][11][12][13][14][15].…”

The effect of magnetic field on the electric breakdown trajectory of high‐voltage electric pulse rock breaking

“…More collisions will occur due to the external magnetic field's confinement of the internal electrons, thus increasing the energy intensity. [26,27] Weng et al [28][29][30] did not introduce the exploration of the magnetic field model in the high-voltage electric pulse rock-breaking mechanism. However, they considered the variation of the current field in the circuit.…”