深部矿井动压回采巷道围岩大变形破坏机理

针对深部动压回采巷道的大变形失稳破坏及其控制难题,建立了深部动压环境下圆形巷道力学模型,导出了塑性区边界隐性方程式。在此基础上,对深部动压巷道塑性区形态演化规律进行深入分析,阐明了第I类及第II类蝶形塑性区形成的力学条件,界定了塑性区恶性扩展及其临界的定义,揭示了深部动压回采巷道的变形破坏机理。结果表明,开采动压影响比常规条下围岩更易产生蝶形塑性区,且蝶叶发育尺寸、塑性破坏范围更大。随着动压影响的增强,巷道区域应力场成为超常规的超高应力场,巷道顶底、两帮的塑性破坏进一步向深部扩展,变形加剧,致使塑性区恶性扩展,最终造成围岩大变形破坏。对于深部动压回采巷道的设计、支护应充分考虑如何避免或降低动压的影响,改善围岩应力环境,减小蝶叶塑性破坏深度,以便更好地维护巷道。

Large deformation failure mechanism of surrounding rock for gateroad under dynamic pressure in deep coal mine

In terms of the large deformation unstable failure and its control problem of deep dynamic pressure in gateroad,the mechanical model of circular roadway under dynamic pressure environment in deep mine was established.Also,the implicit boundary equation of plastic zone around deep dynamic pressure gateroad was deduced.Based on this,the morphology evolution rules of plastic zone in deep dynamic pressure roadway was deeply analyzed.Then the mechanical conditions for the formation of the class I and class II butterfly-shaped plastic zone were illustrated,and the definitions of malignant expansion of the plastic zone and its criticality were made.Finally,the failure mechanism of deep dynamic pressure gateroad was revealed.The results indicate that it is easier for surrounding rock to produce the butterfly-shaped plastic zone under dynamic pressure effect in mining than the normal conditions,and the development size of butterfly leaf,plastic damaged zone are greater.With the increase of dynamic pressure influence,the regional stress field of gateroad becomes extraordinary high stress field and the plastic failure of roof,floor and ribs expand to deep rock mass,which leads to the more serious deformation and formation of malignant expansion of plastic zone.Eventually that cause a large deformation failure of surrounding rock.For the gateroad design and supporting under deep dynamic pressure,how to avoid or reduce the impact of dynamic pressure,improve surrounding rock stress environment and decrease the failure depth of butterfly leaf must be all considered adequately,which are beneficial to the maintenance of gateroad.