ABSTRACT
Some physical phenomena cannot be understood on the basis of statics alone; consideration of dynamics is essential in many instances. Dynamic phenomena bring inertial forces into design analyses. Instead of equations of equilibrium, one must consider equations of motion. Stress or strain waves that are generated by blasting and earthquakes and subsequently propagated through the adjacent rock masses are generally within the elastic range of deformation, so the relationship between stress and strain is given by Hooke's law as in the static case. Reflection and transmission of planes waves at normal incidence to an interface between two different materials must be conserve mass, momenta, and energy. Excavation geometry and amount of extraction, preexcavation stress, and rock mass quality all influence the mode of failure and whether bursting failure may be expected. Guides to hazard mitigation and damage control include reduction of stress and use of support and reinforcement specifically intended for dynamic loading.
