Study on mechanical characteristics and damage evolution law of coal-rock-like under different loading rates

In order to study the influence of loading rate on the strength, deformation and failure modes of specimens, the uniaxial compression tests of coal-rock-li ke specimens at different loading rates are carried out by stiff testing machine. A parallel bonding particle model of coal and rock is established by means of the particle discrete element program ( PFC) and acoustic emission information of specimens damage under different loading rates is recorded in real time. Based on the acoustic e mission information of numerical model, the evolution equation of coal and rock damage is established. The results showed that uniaxial compressive strength continual ly increases with the increase of loading rate; with the increase of loading rate, specimen failure mode transforms from X、V、Y types to a single macro fracture; with th e increase of loading rate, the acoustic emission rate is obviously higher near the peak stress; damage evolution process is basically divided into the initial damage pha se, damage stable development phase and damage rapid development phase; the influence of loading rate on the damage evolution is mainly focused on the stable dev elopment phase.