The Synergistic Retaining Effect of the Intermediate Bridge Between Adjacent Open-Pit Mining Areas and the Internal Dump on the Slope

To address the challenge 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 internal dump. By constructing a mechanical model of the intermediate bridge and the internal dump, and applying the Mohr-Coulomb shear strength theory and soil pressure theory, mathematical expressions were derived to describe the variations in the supporting effect and the three-dimensional mechanical behavior of the internal dump during the demolition of the intermediate bridge. Additionally, a quantitative relationship between the dumping height and the demolition length of the intermediate bridge was established. Based on the principle of equivalence, a two-dimensional equivalent method for analyzing the synergistic mechanical effect of the internal dump was proposed. This method theoretically elucidates the influence of the internal discharge pressure height on the equivalent physical and mechanical parameters. The proposed method was applied to the Zahannaoer open-pit coal mine, where the intermediate bridge demolition project was designed in stages, and the slope stability at each stage was analyzed and verified. The results of this study provide a theoretical and practical foundation for the dynamic demolition design and engineering implementation of intermediate bridges in open-pit coal mines, ensuring both safety and efficiency in mining operations.