Abstract:In order to study the effect of the angle of flaws at the end surface on the dynamic properties of and crack propagation in rock,cylindrical marble specimens of 50 mm×50 mm were manufactured with flaws of different angles. A series of impact loading tests were carried out with a system of split Hopkinson pressure bar(SHPB) with the diameter of 50 mm. The crack propagation and dynamic failure processes were recorded real-timely by a high speed camera. The results show that the dynamic parameters of the marble including the dynamic compressive strength,peak strain and dynamic elastic modulus,decrease first and then increase with the increasing of angles of prefabricated flaw. The cracks initiate almost from or near the tip of flaw and the initiation cracks belong to type II or combined type I-II. The crack initiation angle shows an M-shaped tendency and the crack initiation stress shows a W-shaped tendency with the increase of the flaw angle. The splitting tensile failure is usually observed in the marble specimen intact or with flaw having angle of 90°. The combined tensile-shear failure occurred mainly in the specimen with flaw angle of 45° and the shear failure in specimens with flaw angles of 30° and 60°. The crack propagation characteristics on both sides of the critical angle are rather symmetric. The energy absorption ratio increases first and then decreases with the increasing of the flaw angle. When the end flaw has an appropriate angle to the loading surface,the energy absorption ratio is the largest,indicating that the efficiency of rock breaking can be improved effectively by setting an appropriate flaw angle at the end surface.
李地元,韩震宇,孙小磊,李夕兵. 含预制裂隙大理岩SHPB动态力学破坏特性试验研究[J]. 岩石力学与工程学报, 2017, 36(12): 2872-2883.
LI Diyuan,HAN Zhenyu,SUN Xiaolei,LI Xibing. Characteristics of dynamic failure of marble with artificial flaws under split Hopkinson pressure bar tests. , 2017, 36(12): 2872-2883.
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