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俯采孤岛工作面超前支承压力动态演化规律及卸压技术

Dynamic evolution of advanced abutment pressure in downward-mining isolated panels and pressure-relief techniques

  • 摘要: 针对俯采孤岛工作面矿压显现强烈及巷道围岩控制难题,以山西某矿为工程背景,综合运用理论分析、数值模拟与现场实测方法,系统研究了倾角扰动与孤岛效应耦合作用下的超前支承压力演化机制及协同调控卸压技术。研究结果表明:俯采孤岛工作面条件下,超前支承压力传递路径发生偏转,峰值显著前移且强度增加。以15°俯采角为例,其应力集中系数较水平工况提升约51.5%,塑性区宽度增加16.3%。基于理论分析及FLAC3D数值模拟结果分析,随着俯采角增大,应力峰值呈非线性递增;增加煤柱宽度可缓解巷道围岩应力集中,但其应力削弱效果随煤柱宽度增加而逐渐减弱;受两侧采空区长度差异影响,初采期煤柱应力呈明显非对称分布,该效应随工作面推进及倾角增大呈动态衰减特征。鉴于传统被动调控手段的局限性,提出了基于切断应力传递路径的“定向切顶-钻孔”协同卸压技术,并优选了关键参数。现场应用表明,该技术有效阻断了高应力传递,距工作面120 m范围内巷道两帮、顶底板移近量分别较治理前下降约68%和54%,实现了复杂应力环境下的围岩稳定控制。本研究揭示了俯采孤岛工作面支承压力的时空演化规律,提出了针对性防控策略,为类似复杂地质条件下的安全高效开采提供理论指导与工程借鉴。

     

    Abstract: Downward-mining isolated longwall faces often experience severe abutment-pressure concentration and roadway instability due to dip-angle-induced disturbance and asymmetric goaf constraints. To address these issues, this study uses theoretical analysis, FLAC3D numerical modelling, and field monitoring to investigate the evolution of advanced abutment pressure and to develop an effective pressure-relief strategy. Results show that the dip angle significantly alters the stress-transfer path, causing a forward shift and amplification of the peak abutment pressure. At a 15° inclination, the stress concentration factor and the plastic-zone width increase by 51.5% and 16.3%, respectively, compared with horizontal extraction. The peak stress exhibits a nonlinear rise with increasing dip angle, and although wider coal pillars can reduce stress concentration, the stress-attenuation effect of the pillar diminishes as its width increases. Asymmetric goaf lengths induce an evident nonuniform stress distribution in the coal pillar during the initial extraction stage, which gradually weakens as the face advances. To mitigate the intensified loading, a collaborative destressing strategy via directional roof-cutting and borehole drilling was proposed to interrupt the high-stress transmission path. Field application demonstrates that within 120 m ahead of the face, rib convergence and roof-floor closure were reduced by approximately 68% and 54%, respectively, ensuring effective roadway stability. The study clarifies the stress-evolution mechanism of downward-inclined isolated longwalls and provides a targeted technical solution for safe and efficient mining under complex stress conditions.

     

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