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| Influence of granite inherent microcracks on crack evolution based on the flat-joint contact model |
| ZHANG Rui1,ZHAO Cheng1,2,XING Jinquan1,PAN Haoyu1 |
| (1. Department of Geotechnical Engineering,Tongji University,Shanghai 200092,China;2. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,Tongji University,Shanghai 200092,China) |
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Abstract When simulating the failure of brittle rock,existing studies based on the flat joint model neither consider the nonlinear characteristics of stress-strain curve caused by inherent microcracks,nor take the crack initiation stress,an important indicator of damage evaluation,as the calibration benchmark for micro parameters. Therefore,this study used uniaxial compressive strength,elastic modulus,Poisson's ratio,stress-strain curve characteristics,crack initiation stress,Brazilian splitting tensile strength,Coulomb friction angle and cohesive force as the benchmark to calibrate the micro parameters of the flat joint model for simulating granite failure. The trend relationships between the macro mechanical behaviors and micro parameters were analyzed. The calibrated parameters were used to establish an accurate flat joint model sample,which was compared with a conventional flat joint model sample that does not consider inherent microcracks. Numerical tests of fractured rock compression were carried out. Based on the strain field obtained by the digital image correlation method of the indoor test,the initiation,quantity and distribution characteristics of tensile/shear microcracks were analyzed to verify the calibration process of the flat joint model proposed in this paper. The results show that inherent microcracks influence the characteristics of the stress-strain curve at the macro level,and have a great impact on the crack initiation mode at the tip of the prefabricated flaw and the propagation and distribution law of tensile-shear microcracks at the meso level.
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