Abstract：The propagation behavior of both main cracks and branched cracks induced by two-hole slotted cartridge blasting with different amounts of charge masses in polymethyl methacrylate(PMMA) was studied by the digital laser dynamic caustics experimental system. The results showed that the main cracks induced by the slotted cartridge blasting grew mostly as mode I and showed the tensile fractures. These main cracks did not penetrate the prefabricated cracks close to the borehole to propagate further. The branched cracks were found initiated from the tips of the prefabricated cracks. The initiation and propagation of branched cracks were induced by the tensile stress concentration due to the blasting stress wave diffraction at the ends of prefabricated crack. The opposite branched cracks started to extend towards each other until their coalescence. The propagation velocity and the dynamic stress intensity factor(DSIF) of branched cracks decreased drastically after the coalescence. When the borehole was with less charge mass，the propagation velocity and DSIF of both the blast-induced main cracks and the branched cracks caused were lower，the branched cracks had longer initiation time and both the steady propagation time and the propagation length were shorter，which prolonged the time of coalescence. The dynamic fracture characteristics of main cracks and prefabricated cracks induced by the equally charged borehole were almost the same. The branched cracks induced by the singly charged borehole did not coalesce.
李 清，于 强，朱各勇，韦贵华，徐顺成. 不同药量的切缝药包双孔爆破裂纹扩展规律试验[J]. 岩石力学与工程学报, 2017, 36(9): 2205-2212.
LI Qing，YU Qiang，ZHU Geyong，WEI Guihua，XU Shuncheng. Experimental study of crack propagation under two-hole slotted cartridge blasting with different amounts of charge#br#. , 2017, 36(9): 2205-2212.
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2017, Vol. 36 
