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Abstract
Based on the laboratory experiments of spilt Hopkinson pressure bar (SHPB), a numerical model of PFC2D (2 Dimensional Particle Flow Code) is established. The characteristics of crack number and propagation path closely related to material strain rate effect and failure mode are further analysed from a mesoscopic point of view. The dynamic damage and failure process of joint specimens under impact load are studied. The results show that: (1) Prefabricated joints weaken the integrity of rock and reduce the compressive strength of specimen, (2) According to the law of crack development, the failure stage of specimen can be divided into elastic deformation stage, crack initiation stage, rapid crack propagation stage and slow cracks propagation stage, (3) Prefabricated joints affect the failure characteristics of specimens. The crack propagation and failure modes of specimens have ‘rate effect’. At lower strain rates, the cracks of prefabricated joint specimens with the dip angle of 30° are wing cracks and coplanar cracks. With the increase of loading strain rate, the development of anti-wing cracks becomes more and more obvious. The crack initiation angle of wing cracks ranges from 55° to 80°, and the crack initiation angle of anti-wing cracks ranges from 115° to 130°.
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