Influence of strain rate on the rock fracture propagation law

In order to analyze the fracture propagation law of an Ordovician sedimentary rock under uniaxial compres- sion,the deformation of rock surface was studied by using the loading system,VIC-3D observation system and other test systems. The experimental results show that the dynamic evolution of the whole field during the loading process can be obtained by the VIC-3D observation system. The high strain region of the digital surface of the rock surface is increas- ing continuously,the axial micro-cracks of the rock surface start emerging at the elastic-plastic stage. When the stress reaching 18. 02 MPa,the extension of the secondary crack and the surrounding crack leads to the complete destruction of the specimen. Considering the effect of the strain rate on the mechanical properties of the rock and the characteris- tics of strain fields around the crack of the specimens’ surface,the relationship between the strain rate and the crack growth rate around the main crack Ⅰ,secondary cracks Ⅱ,Ⅲ and Ⅳ are analyzed,and it is found that the fracture rate and the axial strain rate exhibit a strong exponential function correlation. The results of this study reveal the law of the expansion and extension of the Ordovician carbonate sedimentary rocks,which is of great practical significance for the prevention and control of dynamic hazard in coal mine.