NUMERICAL MODELING OF A HIGHLY EXPLOSIVE SOURCE IN AN ELASTIC-BRITTLEROCK MASS

A highly explosive source is input in an elastic-brittle rock mass and the resulting near-source complexities are considered. This study is undertaken with a three-dimensional numerical model similar to the dis crete element method. This model can simulate the creation of the dama ge zone with the associated block motions as well as the elastic wave propagation. Free-field ground motion data are recorded to determine t he reduced displacement potential (RDP). In a fully elastic numerical model, as expected, the RDP computation corresponds to the analytical one-dimensional problem of a spherically symmetric explosive source ac ting in a homogeneous elastic medium. When fracturing occurs, during t he creation of the damage zone, block motions are observed, and the RD P computations are affected. For an ideal system which conserves energ y, the potential elastic energy is converted to kinetic energy during the fracturing process resulting in an apparent RDP which is larger th an in the homogeneous elastic case. This three-dimensional approach is undeniably advantageous where a global description of the heterogenou s effects of block motions and the continuous aspects of wave propagat ion are considered simultaneously.