充填开采含“天窗”薄基岩力学模型

Mechanical model of thin bedrock contains "skylight" under backfill mining

针对第四系资源开采遇到的"天窗"地质构造问题,以存在天窗地质构造的煤矿为背景,建立充填开采含"天窗"水平薄基岩的力学模型—Winkler弹性地基上开孔固支板模型,求解矸石充填条件下含天窗水平薄基岩挠度表达式.在此基础上对薄基岩厚度、天窗尺寸、矸石充填体强度对薄基岩天窗附近应力分布影响进行分析探讨.研究结果表明:薄基岩下表面天窗边界处径向和环向应力都为拉应力;薄基岩厚度、天窗尺寸对天窗边界环向应力影响较大,而对径向应力影响较小,环向应力随薄基岩厚度的增大迅速递增,随天窗尺寸增大逐渐增大;增大矸石充填体强度能显著减小天窗附近应力,矸石充填体强度增大,环向应力大幅度降低,薄基岩天窗附近应力环境显著改善,防止天窗边界处出现破坏裂纹,导致薄基岩局部失稳.

In coal mining at quatemary system, the skylight structure may occur in some mine. Based on the geological structure of skylight at roof in quatemary system, this paper establishes a mechanical model of backfill mining for thin bedrock with skylight -- the model of perforated-clamped-plate on the Winkler elastic foundation. Also, the paper derives a deflection expression for the thin bedrock with skylight under the gangue filling condition. According to the study above, the paper analyzes and investigates the influence on the stress distribution of thin bedrock, including the thickness of thin bedrock, the size of skylight, and the intensity of gangue filling. The study shows that firstly the radial stress and the circumferential stress of skylight border under thin bedrock surface are tension stress; secondly, the thickness and skylight size has great influence on the circumferential stress, the circumferential stress increases rapidly with the thickness increases, and increases gradually with the skylight size increases; thirdly, the thickness and skylight size has little influence on the radial stress; fourthly, the more the gangue filling intensity, the less the sedimentation and the inner stress of thin bedrock, therefore, the bedrock stress environment is improved near the thin skylight area. This prevents the destruction from the skylight border under thin bedrock surface.