Dynamic response and failure mechanism of a large-section chamber group in deep coal mine: A case study

The instability of large-section intersecting chamber groups is a critical problem in deep coal mining, where complex in-situ stress conditions and interactions among adjacent chambers strongly affect surrounding-rock stability. Taking the coal–gangue separation chamber group in Xinjulong Coal Mine as the engineering background, this study investigates the stress distribution, deformation response, and failure characteristics of the chamber group under static and combined static–dynamic loading through numerical simulation, theoretical analysis, and field monitoring. The numerical results indicate that, under static loading, stress concentration in the central rock pillar is controlled by the coupled effects of intersection angle, chamber spacing, and chamber cross-sectional size. Under dynamic disturbance, the stress peak at chamber intersections increases by 9.8%–15.7%, while the stress influence range expands by approximately 50%. Dynamic loading further causes the anchorage structure within the plastic zone to lose bearing capacity, resulting in structural disintegration of the surrounding rock and support failure. A stress superposition model for the surrounding rock of intersecting chambers is established by considering chamber size and intersection angle. The region within the plastic zone where the anchorage structure fails and the stress approaches zero is defined as the equivalent excavation zone, and a formula for calculating its equivalent excavation radius is derived. Field verification is conducted under in-situ conditions, and borehole observations reveal a distinct fractured zone in the surrounding rock, consistent with the theoretical results. This study provides theoretical guidance and technical reference for stability control of large-section chamber groups under similar deep coal mining conditions.​