Study On The Expansion Mechanism Of Rock Crack Under Dynamic Loading

The failure of rock cracks under dynamic loading is a subject which is related to various aspects of geotechnical engineering constructions and risk assessments. The occunence of rock failures in the practice of geotechnical engineering are almost caused by dynamic loading, such as the earthquake load and blast load. In rock fracture mechanics, the static load and impact load have been researched in a certain degree. However, the research for propagation mechanism of rock fracture under a low loading is still not enough. Therefore a series of numerical simulation of the failure of rock fractures under different speed loads will be done in this paper by the expanded distinct element method (EDEM) which embedded with two failure criterion. And the influence of different loading rate to rock failures was known by the comparative analysis of the morphological difference of damage and different mechanical properties.The study of failures of rock cracks under dynamic loading could be further understood as the mechanism of crack propagation under different strain rates, by which the foundation for comprehensive and systematic study of the propagation characteristics of rock fractures under various dynamic loads could be established. At the same time, the locations and risk assessments of important geotechnical engineering practice and constructions could be guided.Through the simulation of the rock models with different angles of pre-existing cracks under a variety of loading speeds by the expanded distinct element method in this paper, the two aspects of effects of the loading rate to the occurrence of rock fissure and the characteristic of rock mass mechanics by the analysis of results. The similarities and differences in the crack occurrence of models under high loading rate and static load were summarized. In the occurrence expansion, there will be more secondary fractures extended in the models under high-speed loading, even to damage regions, and "X"-shaped failure occurrence would be produced at last. In the aspect of mechanical properties of models, it was found that greater stress values would be got in the models under high-speed loading, through the data of stress and displacement in loading plate analyzed. At the same time, the importance of study on stress wave propagation in rock mass under dynamic load was stated through the analysis of mechanical response of rock like models under dynamiload.The crack propagation theory and the rock dynamic fracture mechanics are important theoretical basis to solve the influence of dynamic load on the formation and geotechnical engineering constructions. The dynamic fracture mechanics could be comprehensively studied in the future through the in-depth study of the mechanical response and failure occurrence of the rock failures under dynamic load and to achieve the purposes that could accurately predict the crack propagation and do the risk assessments and so on.