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| Numerical study on mesoscopic mechanical behaviors of granite based on Multi Pb-GBM method |
| LIU Shuaiqi1,2,3,MA Fengshan1,2,GUO Jie1,2,CAO Jiayuan1,2,3,WANG Zhiwen1,2,3 |
| (1. Key Laboratory of Shale Gas and Geoengineering,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;2. Innovation Academy for Earth Science,Chinese Academy of Sciences,Beijing 100029,China;3. College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China) |
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Abstract Granite is widely used in engineering for its superior mechanical properties. A multilevel parallel bonded-grain based model(Multi Pb-GBM) was proposed to revel the micro structure of crystalline granite,in which parallel bonded-grain model(Pb) was introduced to replace smooth joint model(SJ) to represent the grain boundaries. The bonded mode of the samples were clarified into three types including intra-grain contact,inter-grain contact inside one mineral and inter-grain contact between two different minerals. Parameters of the model were calibrated through uniaxial compression tests and Brazil splitting tests,and simulations were conducted to study failure modes and dynamic damage evolution of brittle granite rock under the influence of the grain size distribution coefficient. An intact fracture-monitored system was established based on Fish function,and the behaviors of the micro-fracture were discussed. The results indicate that the grain size distribution coefficient has an effect on the failure modes,tensile cracks are dominant in uniaxial and Brazil splitting tests,and that both UCS and UTS show an increasing tendency with increasing granite crystal size. The number of cracks at grain boundaries of different minerals is larger than that at grain boundaries inside the same mineral. With increasing the grain size coefficient,the number of cracks at grain boundaries gradually decreases while the internal fractures increase. The microcracks first appear at the third level contacts,followed by the fractures at the second level contacts,and then the number of first level cracks increases rapidly. During uniaxial compression tests,a transformation process from inter-grain fracturing with kalium feldspar-quartz boundary to intra-grain damaging within kalium feldspar-plagioclase occurs until macroscopic failure.
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