关键词: 裂隙岩体, 加载应变率, 裂隙倾角, 单轴压缩, 颗粒流

Abstract: Strain rate has important influence on mechanical properties and failure of the fractured rock mass. The influences of medium strain rate on stress-strain, crack tip stress, characteristic stress and damage of rock mass, fracture expansion of crack of sandstone with a single fissure are researched under uniaxial compression using two-dimensional particle flow code (PFC2D). The stress-strain curves of joint rock mass present obviously fluctuation and stress mutation. The stress mutation index is defined in order to quantitatively analyze the degree of stress mutation. The stress mutation fluctuation is more acute with the increase of strain rate; and after peak strength it is stronger than before. The fluctuation amplitude of stress is increased before peak strength but reduced after peak strength with the increase of the fissure angle. The fracture stress of crack is enhanced with the increase of strain rate; and the tangential shear stress is increased on the whole; but the normal stress obviously reduced with the increase of fissure angle. The loading stress when crack tip is fractured, the critical dilatancy stress σd and the peak strength are all increased with the increase of strain rate. The dilatancy of rock mass can be immediately triggered by the fracture of crack tip; and and are generally more close to when strain rate is lower. The more the cracks of damage and macroscopic fracture are, the stronger the degree of damage and fracture of rock mass are with the increase of strain rate; and especially the end effect of specimen is more significant. The initial fracture is begun in the way of I type wing crack; its length is related to the strain rate and the dip angle of fissure.

Key words: fractured rock mass, loading strain rate, fissure angle, uniaxial compression, particle flow code