Simulation Test Study Of Fissured Rock Mass On Crack Propagation Under Explosion

The cracks propagation rules of the fissured rock mass under blasting dynamic loads have been a hot issue in the study of rock dynamics. As the fissured rock mass have the predominent characteristics of anisotropy, non-continuity, which cause the process of stress waves propagation become extremely complex, the distribution of stress wave energy is uneven arrounding blastholes areas, the influence on blast crack initiation, crack propagation, crack extension and crack arrest, resulting in rock crushed unevenly and un-deal blasting effects accompanied with big blocks and bedrocks as well as overbreak-underbreak. Therefore, in order to have a better understanding on the behavior of rock dynamic fracture mechanics and master fissured rock crushing mechanism, research on blasting cracks propagation rules were carried out, which has important practical significance and reference value.This paper, based on domestic and foreign scholars research achievements, adopts method of theorectical analysis combined with physical test to have a further discuss and research on law of crack propagation in fractured rock mass under explosion. Distance and angle of blasting hole to prefabricated crack and fillings were used as variables in physical test, and organic glasses that have almost the same fracture properties with rock in dynamic loads were selected, and models, prefabricated cracks and blasting holes were processed by laser. Prefabricated cracks were fully filled by fillings before explosion, and fixed the detonator in blasting hole in order to guarantee its main charge area to aim at the same location of the model. Then model was covered by veneer, and finally blasting cracks were obtained by detonator explosion.Firstly, the surrounding cracks of blasting hole propagation characteristics of models filled with air, water and clay were respectively analyzed under different distances and angles of blasting hole to prefabricated crack, which obtained the general crack propagation law. At the time wing crack propagated in tensile – shear way, and the length of left end wing crack decreased with increase of distance.Secondly, the paper analysed and researched in-depth on effects on three kinds of fillings for cracks propagation and influence on distance, angle and fillings for cracks propagation were emphatically discussed, which obtained that fillings had sensitivity to blasting crack propagation and three variables had interaction on blasting crack propagation.Lastly, according to analysis and research of physical test results, the experimental results were applied to simple analysis of influence on blasting effect in different angles of the fracture surface and line of hole center, and put forward the measures to improve the blasting effect of the fractured rock mass.