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| Study on the correlation between rock?s mineral compositions and macro-micro friction properties |
| HUANG Man1，2，LU Mengyi1，2，WU Yuewei1，2，LIU Dan3，ZHANG He1，2，HE Zhihai1，2 |
| (1. School of Civil Engineering，Shaoxing University，Shaoxing，Zhejiang 312000，China；2. Key Laboratory of Rock Mechanics and Geohazards of Zhejiang Province，Shaoxing University，Shaoxing，Zhejiang 312000，China；3. State Key Laboratory for Tunnel Engineering，China University of Mining and Technology(Beijing)，Beijing 100083，China) |
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Abstract Mineral compositions is an important factor affecting the macro-micro friction mechanical properties of rock. The macro-micro friction properties of sandstone are studied based on direct shear and nano-scratch tests，the variations of mineral compositions before and after shearing are analyzed using X-ray diffraction，the macro-micro friction coefficients of rock，different minerals and interfaces are statistically obtained，and the friction correlation mechanism between the two is established. The results show that the proportion of hard-phase minerals in the total amount of powder increases after shearing，the proportion of soft-phase minerals decreases. The scratch depth and friction force of hard-phase minerals remain stable，those of soft-phase minerals vary significantly. Statistical analysis of the probability distribution curve of the friction coefficient reveals that each mineral and interface exhibit a single-peak Gaussian distribution. Combined with the analysis of macro-micro friction mechanisms，it is found that the macro friction force of sandstone is influenced by surface asperities and the wear between different minerals，the friction force of hard-phase minerals mainly depends on their inherent properties，the friction force of soft-phase minerals and interfaces is affected by their inherent properties，plastic flow and the extrusion of surrounding minerals. By further quantifying the relationship between macro-micro friction coefficients，the hard-soft phase interface contributes the most to the macro friction coefficient with 52.1%. The research results of the macro-micro friction properties can provide a theoretical foundation for revealing the mechanism of cross-scale friction mechanics.
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