Evolution characteristics of pressure-arch and elastic energy during shallow horizontal coal mining

Abstract

To ensure safety mining during shallow horizontal coal mining based on the monitoring data of the roof weighting of a typical mining engineering in China, the load distribution characteristics of the roof in the mining field were analysed, and the mechanical model of the pressure-arch in the surrounding rock was established. Then the evolution characteristics of the pressure-arch and elastic energy were revealed during shallow coal mining by theoretical and numerical analyses. Results show that the continuous pressure-arch can form when the horizontal stress exceeds the vertical stress, and the elastic energy of the roof is released by the mining unloading effect. The caved zone of the overlying strata is formed below the inner boundary of the pressure-arch. The elastic energy is accumulated in the pressure-arch and the energy becomes the highest at the front arch foot. The sliding of the caved zone along the shear zone in the mining field can induce the strong roof weighting. The concentrated stress and the released energy during each mining stage increase with the working face advancing, and the height of the shear zone also increases. This study can provide a theoretical reference for similar mining engineering.