(1. School of Emergency Management and Safety Engineering，China University of Mining and Technology(Beijing)，Beijing 100083，China；2. State Key Laboratory of Coal Resources and Safe Mining，China University of Mining and
Technology(Beijing)，Beijing 100083，China；3. Beijing Key Laboratory for Precise Mining of Intergrown
Energy and Resources，China University of Mining and Technology(Beijing)，Beijing 100083，China)
Abstract：Coal micro mechanical properties and failure mechanisms are of key importance to supplement and explain the physical and mechanical properties of coal. Nanoindentation tests were carried out to obtain micro mechanical properties of Zhaozhuang coal，molecular dynamics simulation of the macromolecule matrix of Zhaozhuang coal was performed，and their results were compared with each other. The results show that the average hardnesses of Zhaozhuang coal in static and dynamic loading modes are respectively 0.423 and 0.560 GPa，and the average elastic moduli are 4.452 and 5.200 GPa，respectively. The Weibull distribution moduli corresponding to the elastic modulus and hardness of Zhaozhuang coal under the two loading modes are greater than 20. The failure mechanisms at the molecular scale were revealed through nanoindentation molecular dynamics simulations of Zhaozhuang coal macromolecule matrix. The hardness and elastic modulus of Zhaozhuang coal molecular simulation were obtained using Oliver-Pharr method and Hertz theory，which are approximately agreed with the tests. In the simulation process，the potential energy of the system increases while loading but decreases while unloading. The final potential energy is higher than the beginning because of the plastic deformation. When the indenter is embedded，the atomic dense area is formed due to mutual extrusion of coal macromolecules and further，the damaged layer occurs because of the loss of the original bond strength. The research on the structure of coal macromolecule matrix by using radial distribution function and bond angle distribution shows that in the process of coal matrix failure，the order degree of coal macromolecule decreases and the ring structure in coal macromolecule plays an important role in failure resisting.
孟筠青1，2，3，牛家兴1，2，夏捃凯1，2，阚李浩1，2. 纳米尺度下煤的力学性质及破坏机制研究[J]. 岩石力学与工程学报, 2020, 39(1): 84-92.
MENG Junqing1，2，3，NIU Jiaxing1，2，XIA Junkai1，2，KAN Lihao1，2. Study on mechanical properties and failure mechanisms of coal at the nanometer scale. , 2020, 39(1): 84-92.
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2020, Vol. 39 
