Evolution Laws of Mining-induced Stress in Floor Strata and Its Influence on the Stability of a Floor Roadway Affected by Overhead Mining

Based on the geological conditions of a drainage roadway in the Xinglongzhuang coalmine of Shandong province (China), a mechanical model of a working face for overhead mining over a roadway was established, and the laws influencing the mining-induced stress were obtained. The evolution of mining-induced stress in the floor with different horizontal distances between working face and floor roadway was examined using universal distinct element code (UDEC) numerical simulation; the stability of the floor roadway was analyzed. The results of the numerical simulation were verified via on-site tests of the deformation of surrounding rocks and bolt pull-out readings from the drainage roadway. The results indicated that the floor roadway was significantly affected within a certain depth and then the effect weakened with the depth increasing. In view of the roadway stability, the roadway was observed with worse stability of surrounding rocks during the period of the working face mining near the roadway or just passing the roadway; moreover, this exploitation was not safe and needed to strengthen the support for the roadway. The results may provide a scientific basis for determining reasonable locations and support for roadways in Xinglongzhuang coalmine and other coal mines with similar coal measures strata.