Incipient Joint Motion Due to Spherical Explosion

The problem of incipient joint/fault motion due to a spherical explosion in an infinite homogeneous isotropic rock mass is considered analytically. The mechanical response of intact rock is assumed to be elastic. The shear failure criterion for the joint or fault is taken to be of the usual Mohr-Coulomb form, which results in a single scalar quantity for the definition of the stress states at which failure occurs. In some cases it is found that there exist certain unexpected orientations for which shear failure is inhibited, even though the fault is very close to the source. Also, a quantitative description of catastrophic shear failure on a fault or joint depends on detailed time-resolved stress histories; simple quantitative models based solely on total explosive energy, for example, are incomplete.