| The Miluo coal Mine was chosen as the object of this experiment, in order to do further study of the production characteristics of overlying rock fissure. The crack growth law was studied by means of similar simulation experiment, and then the law of fracture was analyzed based on chaos theory. Basing on the finishing of similar simulation experiment and the study of relevant literature, the relationship between the number of cracks and the advancing distance were studied by mathematical method and the fracture characteristics was analyzed by means of the chaos theory.Draw the following conclusion:(1) the number of longitudinal crack of mining seam at the top of the immediate roof and the basic roof approximately linear relationship with the advancing distance of working face. the number of longitudinal cracks of the roof above level were approximately 3 function relation with the advance distance of working surface.(2) transverse abscission fracture was emerged firstly. From the lower layer to the upper layer, the number of cracks is reduced, and the two adjacent edge is developed into a sharp angle. Building a fracture "quadrilateral" or "trapezoid". With the passage of the work, those "quadrilateral" or "trapezoidal" show self similar characteristics.(3) with fault step sinking, in fault line underneath working face roof, longitudinal fissure developed ahead of the working surface, crushing above the working face roof and fracture repeatedly development after irregularities. Caving serious showed chaos and instability. Because of the impact of the fault, the overlying strata on the working surface near the impact of the formation of coal and gas outburst is easy near the fault,roof caving, coal wall and other disasters. |
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