Effect of the waveform of applied pressure on rock fracture process in one free-face model

To investigate rock fracture process due to various applied pressure to a charge hole in one free-face, rising and decay time for the waveforms of the applied pressures were varied. The fracture processes were simulated by a numerical method, based on dynamic finite element method and fracture mechanics. It was cleared that the fracture processes were affected by rising time increasing. From the comparisons between stress wave propagations and crack propagations at various rising times, it was realized that the crack-arrested time could be expected from the propagation time of reflected wave peak phase. The transition between quasi-static and dynamic fracture process was discussed with non-dimensional time C _p t ₀/w, in which C _p is P-wave velocity, t ₀ is the rising time and w is burden. The transition at 2.0-4.0 non-dimensional times. The influence of rock inhomogeneity on fracture process was also investigated.