浅埋薄基岩窄煤柱巷道上覆岩层破断规律与稳定控制研究
发布时间：2019-01-01 20:27
【摘要】：我国西部地区回采巷道主要采用宽煤柱护巷、双巷掘进的方式,该地区煤层赋存特点是埋藏浅、基岩薄,上覆岩层多为较厚的松散层,浅埋薄基岩煤层工作面来压强烈,甚至造成支架压死,但保护煤柱压力较小,工作面侧向压力显现并不剧烈,但随着矿井开采深度的加大,双巷掘进所需留设煤柱宽度也逐渐增大,巷道维护日益困难,因此,为改善巷道维护状况并实现巷道有效控制并提高煤炭采出率,达到安全高效生产的目的,本文综合运用理论分析、数值计算、现场试验等方法,对浅埋薄基岩窄煤柱巷道上覆岩层破断规律与稳定控制技术进行了系统研究,确定了合理的窄煤柱宽度,主要研究成果为:(1)基于弹性地基上的半无限Winkler悬臂梁理论,给出浅埋薄基岩在侧向煤柱内破断位置的计算式及其与基岩悬伸长度l与周期来压步距0l三者间的关系式:(?)并讨论了基岩周期来压步距、基岩厚度及液压支架支撑对基岩侧向破断位置的影响规律:浅埋薄基岩煤层基岩厚度大,周期来压步距大、基本顶侧向破断位置更深入煤柱,在煤柱内形成较大范围的应力降低区,为窄煤柱护巷提供有利的位置。(2)建立多矩形孔围岩分析力学模型,给出矩形巷道围岩应力计算式及煤柱内垂直应力叠加计算式,并分析上覆岩层压力、断面尺寸、侧压系数对其的影响规律,揭示浅埋薄基岩窄煤柱巷道失稳机理:窄煤柱护巷时,受应力叠加影响,巷道肩角处应力集中系数大于6.0,肩角处围岩承受高支承压力的作用,容易剪切失稳,窄煤柱留设宽度较小时,窄煤柱应力集中系数高,容易受压失稳。(3)基于弹性地基理论,给出基岩侧向破断煤柱塑性区宽度计算式:当基岩(基本顶)厚度较大且为唯一主关键层时,基岩的破断不受上覆岩层压力及采掘空间的影响,确定双巷掘进窄煤柱护巷时,合理的煤柱宽度范围为B≤11.6m。采用数值模拟的方法,研究不同煤柱宽度巷道围岩应力分布、变形及破坏规律,进一步确定合理的窄煤柱宽度为10m,煤柱存在正在剪切破坏的稳定承载区域,两帮承载均匀,且实体煤帮承载能力相对较大,应力集中系数相对较高,为较好的应力分配状态,仅在煤帮中部出现拉破坏,控制难度相对小。(4)提出浅埋薄基岩窄煤柱巷道的“两区”(窄煤柱大变形区、实体煤帮高集中应力区)为围岩控制的薄弱区域,开发了两帮“两区”关键部位高预应力、高阻让压,高强度围岩控制技术。依据浅埋薄基岩窄煤柱巷道围岩控制技术,在凉水井煤矿42113工作辅助运输巷进行了工业性试验,现场应用表明,煤帮“两区”关键部位小间距高预应力锚杆支护、高预应力让压锚杆支护、二次支护的围岩控制技术有效控制了围岩变形,实现了围岩及支护结构稳定。
[Abstract]:The mining roadway in the west of China mainly adopts the way of protecting roadway with wide coal pillar and driving with double roadway. The coal seam in this area is characterized by shallow burial, thin bedrock, thick loose strata of overlying rock, and strong pressure in the face of shallow and thin bedrock coal seam. Even causes the support to press dead, but the protection coal pillar pressure is small, the face side pressure appears not intense, but with the mine mining depth increasing, the double roadway driving needs to keep the coal pillar width to increase gradually, the roadway maintenance day by day is difficult, therefore, In order to improve the condition of roadway maintenance, realize the effective control of roadway and increase the rate of coal mining, and achieve the purpose of safe and efficient production, this paper synthetically applies the methods of theoretical analysis, numerical calculation, field test, etc. The breaking rule and stability control technology of overlying strata in shallow and thin bedrock narrow coal pillar roadway are systematically studied, and the reasonable narrow coal pillar width is determined. The main research results are as follows: (1) based on the semi-infinite Winkler cantilever beam theory on elastic foundation, The formula for calculating the breaking position of shallow buried thin bedrock in the lateral coal pillar and its relationship with the elongation of the bedrock and the periodic pressure step of the rock are given as follows: (?) And discussed the influence law of the bedrock period pressure step, the bedrock thickness and the hydraulic support on the bedrock lateral fracture position: the shallow buried thin bedrock coal seam has the big thickness of the bedrock, the period pressure step distance is big, the basic top lateral fracture position is deeper into the coal pillar. A large area of stress reduction area is formed in the coal pillar, which provides a favorable position for the narrow coal pillar protecting roadway. (2) the analytical mechanical model of surrounding rock with multiple rectangular holes is established, and the calculation formula of surrounding rock stress of rectangular roadway and the superposition formula of vertical stress in coal pillar are given. The influence of overlying strata pressure, cross section size and lateral pressure coefficient on the rock overburden is analyzed, and the instability mechanism of narrow coal pillar roadway with shallow and thin bedrock is revealed. When protecting roadway with narrow coal pillar, the stress concentration factor at the shoulder corner of roadway is greater than 6.0, which is affected by stress superposition. The surrounding rock at shoulder angle is subjected to high bearing pressure, which is prone to shear instability, small width of narrow coal pillar, high stress concentration factor of narrow coal pillar, and easy to be unstable under pressure. (3) based on the theory of elastic foundation, The formula for calculating the width of plastic zone of lateral broken coal pillar of bedrock is given. When the thickness of bedrock (basic top) is large and the bedrock is the only main critical layer, the breaking of bedrock is not affected by the pressure of overlying rock and the mining space, so it is determined that when driving into narrow coal pillar to protect roadway in double roadway, The reasonable width range of coal pillar is B 鈮，
本文编号：2398072
[Abstract]:The mining roadway in the west of China mainly adopts the way of protecting roadway with wide coal pillar and driving with double roadway. The coal seam in this area is characterized by shallow burial, thin bedrock, thick loose strata of overlying rock, and strong pressure in the face of shallow and thin bedrock coal seam. Even causes the support to press dead, but the protection coal pillar pressure is small, the face side pressure appears not intense, but with the mine mining depth increasing, the double roadway driving needs to keep the coal pillar width to increase gradually, the roadway maintenance day by day is difficult, therefore, In order to improve the condition of roadway maintenance, realize the effective control of roadway and increase the rate of coal mining, and achieve the purpose of safe and efficient production, this paper synthetically applies the methods of theoretical analysis, numerical calculation, field test, etc. The breaking rule and stability control technology of overlying strata in shallow and thin bedrock narrow coal pillar roadway are systematically studied, and the reasonable narrow coal pillar width is determined. The main research results are as follows: (1) based on the semi-infinite Winkler cantilever beam theory on elastic foundation, The formula for calculating the breaking position of shallow buried thin bedrock in the lateral coal pillar and its relationship with the elongation of the bedrock and the periodic pressure step of the rock are given as follows: (?) And discussed the influence law of the bedrock period pressure step, the bedrock thickness and the hydraulic support on the bedrock lateral fracture position: the shallow buried thin bedrock coal seam has the big thickness of the bedrock, the period pressure step distance is big, the basic top lateral fracture position is deeper into the coal pillar. A large area of stress reduction area is formed in the coal pillar, which provides a favorable position for the narrow coal pillar protecting roadway. (2) the analytical mechanical model of surrounding rock with multiple rectangular holes is established, and the calculation formula of surrounding rock stress of rectangular roadway and the superposition formula of vertical stress in coal pillar are given. The influence of overlying strata pressure, cross section size and lateral pressure coefficient on the rock overburden is analyzed, and the instability mechanism of narrow coal pillar roadway with shallow and thin bedrock is revealed. When protecting roadway with narrow coal pillar, the stress concentration factor at the shoulder corner of roadway is greater than 6.0, which is affected by stress superposition. The surrounding rock at shoulder angle is subjected to high bearing pressure, which is prone to shear instability, small width of narrow coal pillar, high stress concentration factor of narrow coal pillar, and easy to be unstable under pressure. (3) based on the theory of elastic foundation, The formula for calculating the width of plastic zone of lateral broken coal pillar of bedrock is given. When the thickness of bedrock (basic top) is large and the bedrock is the only main critical layer, the breaking of bedrock is not affected by the pressure of overlying rock and the mining space, so it is determined that when driving into narrow coal pillar to protect roadway in double roadway, The reasonable width range of coal pillar is B 鈮，
本文编号：2398072
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