遗留煤柱下伏底板应力演化及巷道围岩力学响应研究

Stress evolution in floor strata beneath remnant coal pillars and mechanical response of roadway surrounding rock

  • 摘要: 针对单一应力指标难以完整表征遗留煤柱扰动下底板应力分布的问题,采用理论分析、数值模拟与现场监测相结合的方法,系统开展煤柱下伏底板应力演化及巷道围岩力学响应规律研究。基于Mohr−Coulomb屈服准则推导出煤柱内承载应力分布函数,建立了多煤柱应力叠加模型,引入应力集中系数、应力梯度及侧压系数,从应力水平、空间梯度、应力状态多维度定量表征底板应力分布特征。研究结果表明:① 底板应力受遗留煤柱扰动呈显著非均匀分布,底板浅部区域应力扰动剧烈且随着底板深度增加呈非线性快速衰减,煤柱对底板的应力扰动主要集中在20~30 m深度范围内。② 应力集中系数、应力梯度及侧压系数对巷道围岩应力与位移峰值均具有明显调控作用:随着应力集中系数增大,围岩应力峰值呈近似线性增长,位移峰值增速持续加快;随着应力梯度增大,围岩应力峰值表现为线性增长,位移峰值增速随之提高;侧压系数>1.0时应力与位移峰值呈非线性快速增长;应力梯度与侧压系数均取较大值时,将造成巷道围岩应力集中与变形明显加剧;围岩位移峰值对参数变化的敏感性高于应力峰值。

     

    Abstract: To address the limitations of fully characterizing floor stress distributions under disturbance induced by remnant coal pillars using a single stress indicator, this study systematically investigated the stress evolution in floor strata beneath coal pillars and the mechanical response of the roadway surrounding rock through theoretical analysis, numerical simulation, and field monitoring. A load-bearing stress distribution function for coal pillars was derived based on the Mohr-Coulomb yield criterion, and a stress superposition model for multiple coal pillars was established. The stress concentration coefficient, stress gradient, and lateral pressure coefficient were introduced to quantitatively characterize the floor stress distribution in terms of stress level, spatial gradient, and stress state. The results showed that ① floor stress was markedly nonuniform under disturbance induced by remnant coal pillars. The stress disturbance was intense in shallow floor strata and decayed rapidly and nonlinearly with increasing depth. The stress disturbance induced by the coal pillars was mainly concentrated within a depth range of 20-30 m. ② The stress concentration coefficient, stress gradient, and lateral pressure coefficient all had marked regulating effects on the peak stress and peak displacement of roadway surrounding rock. As the stress concentration coefficient increased, the peak stress increased approximately linearly, while the peak displacement increased at an accelerating rate. As the stress gradient increased, the peak stress increased linearly, while the rate of increase in peak displacement also increased. When the lateral pressure coefficient exceeded 1.0, the peak stress and peak displacement increased rapidly and nonlinearly. High values of both the stress gradient and lateral pressure coefficient markedly intensified stress concentration and deformation in the roadway surrounding rock. The peak displacement was more sensitive to parameter changes than the peak stress.

     

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