随着我国采煤技术的快速发展，大采高综合机械化开采工艺已成为中厚煤层开采的主要发展方向。为确保大采高工作面的安全高效开采，提高回采率，开展区段煤柱在反复扰动条件下的合理宽度研究具有重要现实意义。由于顺槽掘进期间与回采阶段区段煤柱所处力学条件的客观差异，煤柱在不同阶段保持稳定将存在不同的合理宽度。鉴于现有煤柱宽度计算理论忽略二次回采期间煤柱一侧对另一侧支承压力的影响，且难以定量分析工作面冒落岩体对煤柱的稳定性的影响。为确保顺槽掘进期间，尤其是回采期间煤柱的安全稳定，本文以陕北某矿30109工作面为工程背景，采用室内试验、理论分析和数值模拟相结合的研究方法对该矿30109工作面区段煤柱在不同阶段的合理宽度进行了系统研究，主要结论如下：

（1）区段煤柱需经历顺槽挖掘、一次回采和二次回采三个阶段，在不同阶段煤柱将经受不同程度的扰动影响，并表现出不同的变形破坏特征。区段煤柱的稳定状态与其煤岩体的基本物理力学参数密切相关。通过现场取样及室内试验，得到了陕北某矿30109工作面区段煤柱的基本物理力学参数。

（2）基于大采高区段煤柱在顺槽掘进及一次回采期间的支承压力力学模型，分析了煤柱在顺槽开挖阶段的极限平衡区和破裂区范围。考虑一次回采扰动的影响，探讨了区段煤柱两侧破裂区扩展后的宽度。结果表明：顺槽掘进完成后，煤柱两侧在支承压力下会发生一定程度的弹塑性变形，一次采动将加剧煤柱岩体的塑性破坏。

（3）考虑煤柱一侧支承压力对煤柱整体变形的影响，构建了二次回采期间区段煤柱在支承压力作用下的受力分析模型，根据虎克定律分析了煤柱极限平衡区宽度与煤柱岩体极限拉应变的关系式。在此基础上，提出了二次回采期间煤柱保持稳定的合理宽度计算公式，分析了煤柱极限平衡区宽度的主要影响因素。结果表明：煤柱埋深、岩弹性模量、体极限拉应变及煤柱高度对煤柱极限平衡区宽度影响显著。

（4）应用FLAC3D数值软件对陕北某矿30109工作面大采高区段煤柱在不同阶段和不同宽度条件下的变形范围进行了模拟。分析表明：在顺槽掘进期间，煤柱受施工扰动影响较小，其塑性区范围、应力大小及岩体位移不大。一次回采期间，因采动影响煤柱变形破坏进一步加剧，煤柱承载力较掘进期间有所降低，但能保持稳定。在二次回采期间，因受二次采动影响，煤柱破坏程度最为显著。当煤柱宽度在25m以上时，煤柱在顺槽掘进和回采期间均处于较为稳定的状态；当煤柱宽度小于25m时，煤柱变形严重。

（5）运用上述理论公式对陕北某矿30109工作面大采高区段煤柱，在不同阶段保持稳定的合理宽度进行了分析计算，确定了该工作面区段煤柱顺槽掘进时的合理宽度为19.1m。考虑煤柱在回采期间的安全稳定，最终确定煤柱合理宽度为25m，并给出了合理的支护方案。现场监测结果表明，30109工作面煤柱两侧变形控制效果良好，满足现场生产需求。

With the rapid development of coal mining technology in China, the comprehensive mechanized mining technology with large mining height has become the main development direction of medium-thick coal seam mining.In order to ensure the safe and efficient mining of large mining height face and improve the recovery rate, it is of great practical significance to study the reasonable width of section coal pillar under the condition of repeated disturbance.Due to the objective difference of the mechanical conditions of the coal pillar between the tunneling period and the mining stage, there will be different reasonable widths for the coal pillar to remain stable in different stages.In view of the fact that the existing calculation theory of coal pillar width ignores the influence of one side of coal pillar on the abutment pressure of the other side during secondary mining, and it is difficult to quantitatively analyze the influence of caving rock mass on the stability of coal pillar.In order to ensure the safety and stability of coal pillar during tunneling, especially during mining, this paper takes 30109 working face of a mine in northern Shaanxi as the engineering background. in this paper, the reasonable width of coal pillar in 30109 working face of this mine at different stages is studied Systematic by means of laboratory test, theoretical analysis and numerical simulation.The main conclusions are as follows:

(1) The section coal pillar needs to go through three stages: trench excavation, primary mining and secondary mining. In different stages, the coal pillar will be affected by different degrees of disturbance, and show different deformation and failure characteristics.The stable state of section coal pillar is closely related to the basic physical and mechanical parameters of coal and rock mass.Through field sampling and laboratory test, the basic physical and mechanical parameters of coal pillar in 30109 working face of a coal mine in northern Shaanxi are obtained.

(2) Based on the mechanical model of abutment pressure of coal pillar in large mining height section during tunneling and primary mining, the limit equilibrium zone and fracture zone of coal pillar in the excavation stage are analyzed.Considering the influence of primary mining disturbance, the expanded width of the fracture zone on both sides of the coal pillar is discussed.The results show that after the completion of tunneling along the tunnel, a certain degree of elastic-plastic deformation will occur on both sides of the coal pillar under abutment pressure, and the primary mining will aggravate the plastic failure of the coal pillar rock mass.

(3) Considering the influence of abutment pressure on one side of coal pillar on the overall deformation of coal pillar, the force analysis model of section coal pillar under the action of abutment pressure during secondary mining is constructed. The relationship between the width of limit equilibrium zone of coal pillar and the ultimate tensile strain of coal pillar rock mass is analyzed according to Hooke's law.On this basis, a formula for calculating the reasonable width of coal pillar to keep stable during secondary mining is put forward, and the main factors affecting the width of limit equilibrium zone of coal pillar are analyzed. The results show that the buried depth of coal pillar, elastic modulus of rock, ultimate tensile strain and height of coal pillar have significant influence on the width of limit equilibrium zone of coal pillar.

(4) The deformation range of coal pillar in 30109 working face of a coal mine in northern Shaanxi under different stages and widths is simulated by using FLAC3D numerical software.The analysis shows that during the driving along the tunnel, the coal pillar is less affected by the construction disturbance, and its plastic zone, stress and rock mass displacement are not large.During the first mining period, due to the influence of mining, the deformation and destruction of coal pillar is further intensified, and the bearing capacity of coal pillar is lower than that during excavation, but it can remain stable.During the period of secondary mining, the damage degree of coal pillar is the most significant due to the influence of secondary mining.When the width of coal pillar is more than 25m, the coal pillar is in a relatively stable state during excavation and mining, and when the width of coal pillar is less than 25m, the deformation of coal pillar is serious.

(5) By using the above theoretical formula, this paper analyzes and calculates the reasonable width of the coal pillar in the 30109 working face of a coal mine in northern Shaanxi, which is stable in different stages, and determines that the reasonable width of the coal pillar in this working face is 19.1 m.Considering the safety and stability of coal pillar during mining, the reasonable width of coal pillar is determined to be 25m, and a reasonable support scheme is given.The field monitoring results show that the deformation control effect on both sides of coal pillar in 30109 working face is good, which can meet the needs of on-site production.

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