Cooperative supporting effect of intermediate bridge and inner dump on slope in adjacent open-pit mining area

To solve the problem of dynamic demolition of intermediate bridges, this study investigates the calculation method for slope stability under the synergistic support effect of the intermediate bridge and the inner dump. Based on a constructed mechanical model of the intermediate bridge and the inner dump, and using the Mohr-Coulomb shear strength theory and soil pressure theory, the mathematical expressions for the variation of the supporting effect and the three-dimensional mechanical effect during the demolition process are derived, establishing the quantitative relationship between the dumping height and the demolition length of the intermediate bridge. Based on the idea of equivalence, a two-dimensional equivalent method for the synergistic mechanical effect of the inner dump is proposed, theoretically revealing the influence of the height of the inner dump on the equivalent physical and mechanical parameters. The method is applied to the Zahannaoer Open-pit Coal Mine, where a staged demolition project was designed and the slope stability for each stage was analyzed and verified. The results provide a theoretical and application foundation for the dynamic demolition design and engineering implementation of intermediate bridges in open-pit coal mines.