Abstract: Crack propagation process in the overlying strata with initial crack was studied by using the numerical test of rock failure RFPA. Mining width and initial damage using of numerical test results were analyzed based on the fractal geometry fractal dimension characteristics of cracks distribution. Fractal laws of cracks evolution in the overlying strata were obtained. Results show that there is a clear correspondence between fractal dimension and initial damage rather than initial crack inclination. Different amount of initial damage is corresponded to the different fractal dimension of cracks distribution. Especially in the mining ending stage, fractal dimension of rock fracture induced by mining with initial damage is increased linearly. The greater initial damage is that the greater the fractal dimension of cracks distribution when mining ending. A new way is provided for studying on fractal dimension of cracks distribution induced by mining when random distribution of cracks.

Key words: mining rock, cracks, fractal dimension, evolution laws