developing discrete element model of cracking jointed llimestone due to blast-stress wave propagation

In this study, the effect of joints on rock breakage due to blast stress wave propagation in limestone has been investigated. the required rock strength properties were measured from limestone specimens extracted from the angooran lead-zinc mine located in the northwest of iran. also, the geometrical properties of the three joints were given from the benches of mine. the particle flow code in two dimensions (pfc2d) has been used to model applying blast pressure to the inner walls of 6 holes; this code was based on the discrete element method (dem). the obtained results showed that producing large pieces of rocks and back-break processes increased by making larger the distance between holes and free surface (b). also, decreasing b caused to increase in the production of powdered limestone around the holes. dem models confirmed when the stress wave reached empty spaces between joint surfaces, it lost a large part of its energy and the wave passed from the joints could not break limestone well. furthermore, creating a large number of cracks around the holes showed that the powdered areas started to develop by propagating the stress wave. comparing the results obtained from dem models with experimental data showed that the discrete element method was an appropriate method to simulate the rock fracturing process during the blast wave propagation. also, the blast wave propagation was modeled well in the plane strain condition.