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 Cpt0/w , in which Cp is P-wave velocity, t0 is the rising time and w is burden. The transition existed at 2.0-4.0 non-dimensional times. The influence of rock inhomogeneity on fracture process was also investigated.
一自由面破砕における装薬孔内壁に作用する圧力の時間的変化させた数値解析を行い, 圧力波形と破壊形態との関係について基礎的な検討を行った｡ その結果, 圧力波形が異なると破壊形態は顕著に異なること, 破壊形態は, 主として圧力の立ち上り時間に依存することを示した｡ また, 亀裂進展と波面走時との関係から, 破壊が終息するまでの時間は, 作用圧力のピークに対応する反射波の到達時間で大略表現されることを明らかにした｡ さらに, 圧力の立ち上がり時間を装薬孔中心への反射波初動の到達時間で除した無次元時間により種々の条件における解析結果を整理し, 動的破壊〜準静的･静的破壊への遷移領域が無次元時間2.0-4.0の範囲にあることを明らかにした｡ 最後に, 強度不均一性の程度が破壊形態に及ぼす影響の検討を加えた。