RESEARCH ON THE INFLUENCE OF ROCK PORE STRUCTURE ON ROCK B' AKING BY HIGH VOLTAGE PULSES

The electrical breakdown of rock subjected to high -voltage electric pulses is a prerequisite for electric fragmentation and is the priority in research on the mechanism of electro-pulse rock breaking. Many studies believe that rock pores have a controlling effect on electro-pulse rock breaking. but how they influence electrical breakdown and rock breaking is not clear. In this paper. a mathematical model of field strength of a porous rock subjected to electric pulses is derived with field strength inside the rock as the evaluation index, and a two-dimensional simulation of field strength is performed to conduct numerical simulation research on the influence law of rock breaking by electric pulses. Several findings are as follows: (1) the field strength inside the rock is distorted by pores. the field strength at the junction of a pore and matrix is the highest, and electrical breakdown first occurs at the edge of pores; (2) more rock pores and shorter pore spacing are conducive to higher field strength; (3) the size, shape and orientation of pores have an important influence on field strength. The larger effective acting surface between a pore and electric field lines leads to higher field strength. making electrical breakdown and rock breaking more likely. An experiment of electrical breakdown and fracturing of marble and sandstone is carried out to further clarify controlling effect of pores.