Study of the Dynamic Development Law of Overburden Breakage on Mining Faces.

Based on the geological conditions of overburden rock, the dynamic development law of overburden breakage was investigated by theoretical analysis and similarity model experiments in this paper. The formula of the compressive strength and No. ratio was obtained by testing the compressive strength of cylinder samples of similar materials. It can be seen from the overburden fracture evolution model established by theoretical calculations and similarity model experiments that the overlying rock layer’s breakage law is consistent. Additionally, the height of the “three zones” and the law of the fracture angle are basically consistent. Obtaining the synchronous collapse of the overlying strata controlled by the key strata, the interval of the upper key strata is larger than that of the lower key strata, and the mining interval is approximately double the size of the deformed rock height. According to the overburden movement, the distribution law of the overburden separation rate is obtained. The strain in the stress concentration area is negative, and when the stress is released suddenly, the strain increases rapidly. Fracture development is detected by the p-wave velocity in the model. Moreover, certain guidance for the horizon selection of high and low-level gas drainage roadways is provided by this study.