Measurements of Cracks of the Sides to Determine Stability

The aerometric tests of roads were carried out in the chosen coal seams to find the variations of a frequency of cracks according to the distance from the side, variations of a frequency distribution of these cracks in time and also their distribution under influence of mining operations. The results of aerometric tests showed that the frequency of cracks according to the distance from the sides has the Poisson distribution. The discrete stochastic process of variations of the frequency of cracks in time was found. The depths of ruptured zones were determined on the basis of a density of "holes corresponding to the cracks". For the chosen conditions the depth of the ruptured zone developed intensively within 90 days from the completion of the working and was 1,6 m on an average. Enlargement of the ruptured zone lasted one year and after that period was stopped in most cases.