Study on Crack Dynamic Evolution Law of Mining Surrounding Rock

In order to study the crack dynamic evolution law of the mining surrounding rock, with the study method of the site test and observation, a borehole TV m ethod was applied to the observation of the roof and floor cracks and the acoustic detection method was applied to the seam cracks in front of the coal mining face.The results of the observation data processing showed that the cracks in the roof and floor would be a separation crack, vertical crack, oblique crack, lateral crack and other crack forms.According to the different crack density at the different distance locations of the coal mining face, the mining cracks could be divided to an original zone, a derivative zone, linkage zone and a reduction zone . According to the acoustic velocity wave features and the advance support pressure distribution, the seam cracks in t he front of the coal wall could be divided into an original zone, a derivative zone, an expanded zone and a linkage zone and could provide the references to improve the gas drainage system.