关键词: 煤与瓦斯突出, 掌子面揭煤, 受力模型, 保护岩柱尺寸

Abstract: In the coal uncovering construction of tunnels prone to coal and gas outbursts，scientifically determining the thickness of the protective rock pillar is a core technical challenge for preventing and con⁃ trolling dynamic disasters. To overcome the limitation of traditional empirical methods，which lack a quanti⁃ tative calculation basis，an analytical model based on the thin-plate theory of elasticity is established，com⁃ prehensively considering gas pressure，surrounding rock confinement effects，and the spatial geometric characteristics of the tunnel face (such as excavation width and height)，the differential equation governing the plate's bending is derived. An analytical formula for the required rock pillar thickness is then obtained using the maximum tensile stress criterion. Theoretical analysis reveals that the rock pillar thickness is lin⁃ early and positively correlated with gas pressure，nonlinearly and positively correlated with tunnel excava⁃ tion width and height，and negatively correlated with the uniaxial compressive strength of the surrounding rock，thereby elucidating its multi-factor coupling mechanism. Field validation at the Baoding 2# Tunnel demonstrated that the theoretically calculated thickness of 3.44 m is 9.2% greater than the measured value of 3.15 m，with the error well within the acceptable engineering range (≤10%). The conservative nature of the theoretical value effectively provides a safety factor of 1.12，satisfying the requirements stipulated in the "Regulations for the Prevention and Control of Coal and Gas Outbursts." This research achieves a transition from empirical estimation to theoretical calculation for rock pillar thickness，providing a quantitative design basis for safe coal uncovering in tunnels under complex geological conditions and offering significant practi⁃ cal guidance.

Key words: coal and gas outburst, coal uncovering at the tunnel face, mechanical model, protective rock pillar dimensions