OFFICIAL the high speed of the phenomenon. On the other hand, in the finite element model, the rock is considered a homogeneous and fracturable elastoplastic material. This requires laboratory parameters to characterize its behavior in both the elastic and plastic zones. Using the Mohr-Coulomb failure criterion (Duncan and Christopher, 2007), failure is established in the finite element mesh; furthermore, by considering the fracture strength according to Griffith (1988), we can determine the propagation of the cracks. The fundamental parameters required to construct the finite element model are: • Elastic Modulus (Young's Modulus). • Poisson's ratio. • Rock density. • Stress at uniaxial compression (UCS). • Tensile stress. • Wave velocity p (Vp) • Wave velocity s (Vs). WAVE THEORY The seismic waves transmitted through the rock mass are classified as body and surface waves. Those relevant for near-field studies are the body waves, which are classified as follows: Longitudinal Waves (P), where the vibrational motion of the particles occurs in the same direction as propagation. These waves are transmitted via compression and tension. Transverse waves (S), where the vibrational movement of the particles occurs perpendicular to the orientation of propagation; these are recorded after the P-waves. The propagation velocity of these waves is a function of the elastic constants of the medium (see Equations 8 and 9). If we assume a typical value for Poisson's ratio ($\nu$) of 0.25, it can be shown that P-waves are transmitted at a velocity nearly twice as fast as transverse waves. As indicated above, waves can be represented as forces transmitted to the rock mass; therefore, P-waves have high relevance in determining the maximum vibrational "support" capacity of the rock mass before matrix rupture occurs. . =ඨ (1− ) (1+ )(1−2 ) (8)
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