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| A NEW METHOD FOR DETERMINING DYNAMIC FRACTURE TOUGHNESS OF ROCK USING SCDC SPECIMENS |
| YANG Jingrui1,ZHANG Caigui1,ZHOU Yan1,ZHU Zheming1,WANG Qizhi1,2 |
| (1. Department of Civil Engineering and Applied Mechanics,Sichuan University,Chengdu,Sichuan 610065,China;2. State Key Laboratory of Hydraulics and Mountain River Engineering,Sichuan University,Chengdu,Sichuan 610065,China) |
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Abstract The large size(150 mm×80 mm) and single cleavage drilled compression(SCDC) specimens were impacted by the large-diameter(?100 mm) split Hopkinson pressure bar(SHPB),and the dynamic toughness of fracture initiation and propagation of sandstone were determined using the experimental-numerical-analytical method. The time of crack initiation and the speed of crack propagating were sequentially measured with the crack propagation gauge(CPG) glued near the crack tip of the specimen,which were proved to be more accurate and sensitive than the ordinary strain gauges on the corresponding position for the same specimen. The experimental-numerical-analytical method considered the effect of inertia and the speed of crack propagation on the dynamic stress intensity factor with the finite element calculation and the semi-analytical modification for the determination of dynamic fracture toughness of rock and was more suitable than the quasi-static method. Both the dynamic toughness of crack initiation under the different dynamic loading rates and the dynamic toughness of crack propagation with different cracking speeds obtained with the experiment-numerical-analytical method were increased with the increasing of dynamic loading rate and cracking speed respectively. Finally,the possibility of achieving crack arrest using SCDC was discussed through analysis of cracking time of the strain gauges positioned on the path of crack propagation.
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Received: 28 April 2014
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