Research On Dynamic Splitting Crack Propagation Of 13-1 Coal In Panji Coal Mine

In the mining of coal resources,coal and rock masses face the threat of impact loads such as coal and gas outbursts and rock bursts.When coal is subjected to impact loads,its compressive strength is several times the tensile strength.Therefore,the coal crushing caused by impact is mainly caused by the tensile effect of stress waves on the coal.The most intuitive feature of coal crushing is the expansion of coal surface cracks.By studying coal crack propagation methods with different lateral impact speeds,it can provide a theoretical basis for understanding the destruction of coal by dynamic disasters in deep coal mining,preventing coal mines from dynamic disaster accidents and improving coal production efficiency.In this paper,using the separated Hopkinson pressure bar(SHPB)experimental device,combined with the digital image correlation(DIC)technology,the dynamic tensile strength of coal under different lateral impact speeds and the growth mode of surface cracks are studied,and use LS-DYNA numerical simulation software to simulate the dynamic splitting experiment of coal,and the following conclusions are obtained:(1)The dynamic tensile strength of coal has an obvious strain rate effect,and its dynamic tensile strength increases with the increase of impact speed.(2)With the increase of impact velocity,the displacement increment of the displacement field of the coal specimen along the axial direction of the rod gradually decreases,and the displacement increment of the displacement field along the radial direction of the rod gradually increases,and the specimen is along the radial direction of the rod.The increase in the displacement increment of the displacement field in the direction is greater than the decrease in the displacement increment of the specimen in the axial direction of the rod,indicating that the specimen is mainly tensile failure in the dynamic splitting experiment.(3)During the crack propagation of the specimen,the width of the main crack increased with the increase of the impact velocity.The impact velocity affects the growth mode of coal surface cracks:when the impact velocity is 8.31m/s,the coal surface cracks extend from the edge of the specimen to the center of the specimen;when the impact velocity is 11.51m/s,the coal surface cracks extend from the center of the specimen to the center of the specimen.The edge of the specimen expands;when the impact velocity is 15.27m/s,the coal surface cracks expand from the edge of the specimen to the center of the specimen.(4)In the numerical simulation study,the crack growth law and failure characteristics obtained by the simulation are consistent with the experimental results.At the same time,it was also found that when the impact speed does not exceed 9.5m/s,the damage mode of coal is mainly the expansion and penetration of its inherent microcracks;as the impact speed increases,the damage mode of the coal will change.When it reaches 13.5m/s,the failure mode of coal is not only the expansion and penetration of cracks,but also crushing failure,and more new cracks are generated during the failure process.Figure 43 Table 5 Reference 80...