Appling Wavelet Analysis to Identify Image Ridge of Crack Width in The Coal Mining´s Roof Interior

The slump of coal mining´s roof is one of the mine´s great calamities in underground exploitation, the influence factors of the roof unsteadiness is rather complex. The essence of crack evolution is rock transform. Although the crack of rock are different between each other, from the viewpoint of fracture mechanics, the crack creating always include 3 stages that turn into and grow slowly, expand and rupture instantly, at the same time, every stage of transform leaves a lot of transmute traces in the crack. Through observe experiment, the relationship between stress and crack can be obtained, but having no crack´s actual width. This paper applies the wavelet analysis to identify the image, which reflects the act.ual position of the inside crack. Though the CT, the image ridge can be checked out, and the relationship between the ridge and actual crack can be defined by the linear-return method.