Study on the strength characteristics of sandstone subjected to coupled static and dynamic loads from the perspective of microscopic crack propagation

A series of engineering dynamic disasters, such as rock bursts and roof caving, are closely related to the damage and strength characteristics of rock under dynamic loading. Research on this topic is helpful for accurately understanding the mechanism of rock dynamic disasters, making predictions in advance and taking appropriate measures to reduce losses. To further study the dynamic failure characteristics of rock, a theoretical model of dynamic wing crack propagation in sandstone under the condition of coupled static and dynamic loads was proposed. The effects of the strain rate, prestatic stress and confining pressure on the damage process and strength of sandstone were quantitatively revealed by a theoretical model. The proposed dynamic wing crack propagation model actually represents the tensile damage of rock and is suitable for the macroscopic tensile fracture of rock under the action of a dynamic load. Compared with the SHPB experimental results, the theoretical model can effectively predict the coupled static and dynamic strengths of sandstone and explain the damage and fracture process. In addition, the differences between the theoretical model and the experimental results were analysed in detail. The results of this study can provide a theoretical reference for further understanding the occurrence mechanism of rock mass dynamic disasters and provide a theoretical model basis for future numerical simulation research.