Research on influence of stress-strain evolution in immediate floor before and after excavation face on origin floor heave in coal mines roadways

Abstract The floor heave is one of the most acute issues of underground mine roadways stability problem. With an increase in mine depth, the floor heave becomes more dramatic. Analysis shows that rock bolts reinforcement is the most advanced and worldwide method of floor heave control. The current mine roadway support systems in Ukraine usually do not provide measures to floor heave control. As a result, floor heave values exceed 0.7-1.0 m, which leads to disruption of transport chains and failure of ventilation regime. In this paper, for the typical conditions of coal mines located in Pokrovsky, Dobropilsky districts and Western Donbass, stress-strain evolution in roadway’s bottom before and after excavation face was studied. Ansys code was used to analyze the evolution of stress and strain in immediate floor of roadway before and after excavation face. It was found that rocks in immediate floor undergo cyclic loading and alternating strains. Before and after excavation face a zone of increased stress and a stress relief zone are formed respectively. Thus, in the immediate floor behind the excavation face cracks are formed and structurally defects are branched. This initiates the origin of floor heave process. The control of the immediate floor delamination after excavation face can be ensured by a timely installation of rock bolts in the excavation face with their inclination to roadway face. The most appropriate bolt inclination coincides with the contour of the stress concentration zone, which can be determined from the results of numerical modeling.