Bending energy storage mechanical model of layered composite roof structure in coal mining

The Layered Composite Roof Structure (LCRS) is a common bearing structure consisting of multiple layers of rock above a coal seam, and the energy stored in this structure plays an important role in the occurrence of rockburst. Few studies have been conducted on the theoretical modeling of energy storage in LCRS. This study theoretically developed a bending energy storage model for LCRS under three conditions, and the theoretical model was verified by simulation and experimental data. The results show that the established model can quantify the stress and bending strain energy distributions of LCRS. The bending strain energy distribution is closely related to the position of the neutral axis and the presence of a thick hard layer. When the neutral axis is located in the lower rock beam, it will store more bending strain energy, and the energy stored in LCRS with a thick hard layer before fracture is greater than that without. The distribution rule of stress and strain energy density in the theoretical model basically corresponds to the numerical simulation results, and the errors between five of the six experimental results and the theoretical model proposed in this study were below 7%.