Damage Evolution of Surface Soil and Buried Gas Pipelines Under Mining-Induced Subsidence in Goaf Areas

To address the potential threat of surface subsidence caused by coal mining to the safe operation of buried gas pipelines in goaf collapse areas, this study investigates the geological conditions of the Mugu Coal Mine in Shanxi Province, China, and a gas pipeline passing through its surface mining area. Using a combination of numerical simulations and physical analog modeling, the mechanical response and deformation characteristics of the pipeline under mining-induced influences were systematically analyzed from three perspectives: the failure mechanisms of surface soil, the pipe–soil interaction behavior, and the damage evolution of the pipeline within the goaf. The research reveals a separation-induced failure pattern of the gas pipeline in mining-affected areas, referring to the mechanism in which differential settlement causes pipe–soil detachment, leading to unsupported bending deformation and stress concentration. Results show that the subsidence basin expands rapidly when the working face advances between 150 m and 210 m. Before this stage, the pipeline and surface soil deform synergistically with a symmetric subsidence curve centered on the goaf and uniformly distributed loads, showing no significant damage. During this stage, non-synergistic deformation occurs, leading to separation between the pipeline and soil. The maximum subsidence point shifts away from the center, destroying symmetry and causing stress concentration at the mining boundary, the advancing working face, and the goaf center, resulting in severe bending and rapid failure. After this stage, the pipe–soil interaction restabilizes with reduced separation height and extent, though pipeline deformation and damage continue to increase gradually. These findings provide a theoretical basis for engineering design optimization, targeted reinforcement measures, and monitoring strategies for gas pipelines in similar goaf collapse areas.