RESEARCH ON THE INFLUENCE OF ROCK PORESTRUCTURE ON ROCK BREAKING BYHIGH VOLTAGE PULSES

摘要

The electrical breakdown of rock subjected to high-voltage electric pulses is a prerequisite for elec- tric fragmentation and is the priority in research on the mechanism of electro-pulse rock breaking. Many studies believe that rock pores have a controlling ef- fect on electro-pulse rock breaking, but how they in- fluence 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 dis- torted by pores, the field strength at the junction of a pore and matrix is the highest, and electrical break-down 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 orienta- tion of pores have an important influence on field strength. The larger effective acting surface betweena 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.