层间距对“上垮--下柱”复合残采区中层弃煤矿压显现的影响研究.pdf

万方数据 万方数据 太原理工大学硕士研究生学位论文 I 层间距对“上垮-下柱”复合残采区中层弃煤 矿压显现的影响研究 摘要 随着社会经济的快速发展，我国对煤炭的需求量也在日益增加，而煤 炭作为不可再生资源，其保有量日趋减少，为了保障国民经济的持续发展， 急需对复杂条件下的遗煤资源进行开采，其中复合残采区中层弃煤在我国 许多矿区广泛赋存，中层弃煤采场岩层运动受到多种因素的影响，其中层 间距是影响中层弃煤顶底板破坏情况的主要因素。由于煤层间距的不同， 会导致中层弃煤采场围岩矿压显现的差异，进而影响中层弃煤的安全开采， 只有掌握不同层间岩层厚度条件下的中层弃煤采场矿压显现规律，才能对 类似条件下的开采起到广泛的指导作用，为矿压灾害的防治提供参考。 在前人研究的基础上，选取大同煤矿集团晋华宫煤矿“上垮-下柱”复合 残采区中层弃煤为研究对象，运用现场调研、理论分析、数值模拟等手段， 研究不同层间岩层厚度条件下中层弃煤采场岩层的应力分布、移动变形和 覆岩结构形式的变化规律，分析了层间距与顶底板岩层破坏情况的关系， 从层间距的角度出发，进一步探讨了中层弃煤可采性的评价方法，进而完 善复合残采区中层弃煤安全开采的理论基础。主要研究内容及成果如下 （1）中层弃煤采场围岩应力分布的层间距效应主要表现在随着下位 层间距的增大，卸压区范围随之减小、应力集中区范围随之增大，下位层 间距为 30m 时应力集中系数最小并且卸压效果好；上位层间距主要对煤柱 上方位置的应力分布影响显著，上位层间距为 12m 时应力集中系数最小。 万方数据 太原理工大学硕士研究生学位论文 II （2）中层弃煤采场围岩移动变形的层间距效应主要表现在柱采区域 上方的位置，而对遗留煤柱上方岩层影响不大中层弃煤最大下沉量的变 化速率随下位层间距的增加而逐渐增大，下煤层采动对中层弃煤的影响程 度逐渐减弱；中层弃煤的最大位移量随上位层间距的增加而减小，但是下 沉量的变化速率不同，当上位层间距大于 9m 时，变化速率显著增加。 （3）中层弃煤采场围岩结构的层间距效应表现在下位层间距主要影 响中层弃煤底板的结构形式，当下位层间距大于 30m 时，下控制层受到上 下煤层及中层弃煤多重采动影响，仍然能够控制上覆岩层的运移，稳定性 良好。在下位层间岩层和遗留煤柱稳定的情况下，随着中层弃煤的开采， 不同上位层间距对顶板的垮落特征具有一定的影响，在上位层间距大于 12m 时，上位层间岩层不发生破断，形成“岩－矸”类拱结构；在上位层间 距小于 12m 时，上位层间岩层出现垮落、破断现象，通过简化模型，分析 支架控顶距与直接顶抗拉强度的关系，得到上位层间岩层的最小厚度 hx为 T k x σ qL h 2 3 。 （4）根据下位层间距与坚硬岩层破断距的关系，得到中层弃煤底板存 在下控制层结构的临界下位层间距 h0，即 2 max 0 max l hh L     ；根据上位层间岩层 厚度与破坏深度的关系，得到中层弃煤顶板存在上承载层结构的临界上位 层间距[h0]，即      tan 24 0 24 cos2 cos                 π e π X h。 （5）从层间距的角度出发，将复合残采区中层弃煤顶底板的结构形式 归纳为三种类型下控制层不稳定、下控制层稳定但上承载层不稳定、下 万方数据 太原理工大学硕士研究生学位论文 III 控制层上承载层均稳定。进一步形成了“上垮-下柱”复合残采区中层弃煤 可采性评价的方法。 关键词复合残采区，层间距，应力分布，移动变形，覆岩结构，可采性 万方数据 太原理工大学硕士研究生学位论文 IV 万方数据 太原理工大学硕士研究生学位论文 V STUDY ON THE INFLUENCE OF COAL SEAM SPACING ON THE MINING PRESSURE BEHAVIOR IN MIDDLE ABANDONED COAL SEAM WITH “UPPER LONGWALL-LOWER PILLAR“ RESIDUAL AREAS ABSTRACT With the rapid development of social economy, the demand for coal is also increasing. As a non-renewable resource, the coal reserves are decreasing. In order to ensure the sustainable development of national economy, it is urgent to mine the residual coal resources under complicated conditions. Among them, the middle abandoned coal in compound residual mining areas is widely existed in many mining areas in China, and the rock layer movement of the middle abandoned coal stope is affected by many kinds of factors. The interval between coal seam is the main factor affecting the failure of middle abandoned coal roof and floor. Due to the difference of coal seam spacing, it will lead to the difference of strata behaviors of middle abandoned coal surrounding rock, and then affect the safe mining of middle abandoned coal. Only by grasping the law of mining pressure appearance of middle abandoned coal under different interlayer rock thickness conditions, can it play a broad guiding role in mining under similar conditions, and provide reference for the prevention and control of 万方数据 太原理工大学硕士研究生学位论文 VI mine pressure disasters. On the basis of previous studies, this paper chooses the abandoned coal in the middle of the “upper longwall-lower pillar“ composite residual mining area of Jinhuagong Coal Mine of Datong Coal Mine Group as the research object. By means of field investigation, theoretical analysis and numerical simulation, it studies the law of stress distribution, moving deation and overburden structure about middle abandoned coal surrounding rock under different rock strata thickness conditions, and the relationship between the layer spacing and the failure of middle coal roof and floor is analyzed. From the perspective of the layer spacing, the uation of middle coal mining feasibility is further discussed, and the theoretical basis of safe mining of abandoned coal in the middle of compound residual mining area is perfected. The main research contents and results are as follows 1 The layer spacing effect of the surrounding rock stress distribution in the middle coal seam stope is mainly manifested as follows as the spacing of the lower layer increases, the range of the pressure relief zone decreases, and the range of the stress concentration zone increases. When the spacing of the lower layer is 30 meter, the stress concentration factor is the smallest and the pressure relief effect is good. The upper layer spacing mainly affects the stress distribution at the position above the coal pillar. When the upper layer spacing is 12 meter, the stress concentration factor is the smallest. 2 Thelayerspacingeffectofthesurroundingrockmovement 万方数据 太原理工大学硕士研究生学位论文 VII deation of the middle coal seam stope is mainly reflected in the position above the column mining area, but has little effect on the rock layer above the remaining coal pillar the change rate of maximum subsidence of middle coal seam increases with the increase of interval between lower coal seams, the influence degree of lower coal mining on middle coal seams decreases gradually. The maximum displacement of middle abandoned coal decreases with the increase of upper layer spacing, but the change rate of displacement is different. When the distance between upper layers is greater than 9 meter, the rate of change is significant increase. 3 The layer spacing effect of the surrounding rock structure of the middle coal seam stope is as follows the spacing of lower layer mainly affects the structure of the the middle coal seam floor.When the lower layer spacing is greater than 30 meter, the lower control strata are affected by multiple mining of upper-lower and middle abandoned coal seams, and can still control the movement of overlying strata with good stability. Under the condition of the stability of the lower interlayer rock layer and the remaining pillars, with the mining of the middle coal, the different upper layer spacing has certain influence on the roof caving characteristics. When the upper layer spacing is greater than 12 meter, the upper interlayer rock layer do not break, ing the “rock-gangue“ type arch structure; when the upper layer spacing is less than 12 meter, the upper interlayer rock layer cave and break. By simplifying the model, the relationship between the controlled roof distance and the direct roof tensile 万方数据 太原理工大学硕士研究生学位论文 VIII strength is analyzed. The minimum thickness of the upper interlayer rock layer is T k x σ qL h 2 3 . 4 According to the relationship between the lower layer spacing and the breaking distance of the hard rock layer, the critical lower layer spacing can be obtained. When the structure of lower control strata in the middle coal seam floor is exist, the critical lower layer spacing is 2 max max 0          L l hh. According to the relationship between the upper layer spacing and the depth of failure, the critical spacing of the upper layer in the presence of the structure of the roof bearing layer of the middle coal seam is obtained, that is  tan 42 0 cos 2cos 42 π X he π               . 5 From the perspective of layer spacing, the structural s of the roof and floor of the middle abandoned coal can be divided into three types the lower control layer is unstable, the lower control layer is stable but the upper bearing layer is unstable, and the upper bearing layer and lower control layer are stable. Further, a for uating the mining feasibility of the middle abandoned coal in the “upper longwall-lower pillar“ composite residual mining areas is ed. KEY WORDS composite residual mining area, coal seam spacing, stress distribution, moving deation, overburden structure, mining feasibility uation 万方数据 太原理工大学硕士研究生学位论文 IX 目录 摘摘要要.........................................................................................................................................I ABSTRACT..............................................................................................................................V 目目录录......................................................................................................................................IX 第一章第一章 绪论绪论...............................................................................................................................1 1.1 研究背景.......................................................................................................................1 1.2 研究意义.......................................................................................................................3 1.3 研究现状.......................................................................................................................4 1.3.1 近距离煤层群开采研究现状.............................................................................4 1.3.2 残煤复采研究现状.............................................................................................5 1.3.3 采场顶板岩层移动变形研究现状.....................................................................7 1.3.4 采场底板岩层移动变形研究现状.....................................................................9 1.4 研究内容.....................................................................................................................10 1.5 研究方法及技术路线.................................................................................................11 第二章第二章 工程概况与工程概况与试验试验设计设计.................................................................................................13 2.1 工程概况.....................................................................................................................13 2.1.1 地质特征...........................................................................................................13 2.1.2 开采条件...........................................................................................................15 2.2 数值模拟试验设计.....................................................................................................17 2.2.1 UDEC 软件简介................................................................................................17 2.2.2 数值模型的建立...............................................................................................17 2.2.3 试验目的及方案...............................................................................................20 2.3 本章小结.....................................................................................................................21 第三章第三章 层间距层间距对对复合残采区中层弃煤应力分布的复合残采区中层弃煤应力分布的影响影响.................................................... 23 3.1 概述.............................................................................................................................23 3.2 不同下位层间距条件下中层弃煤的应力分布特征.................................................23 3.2.1 下部煤层开采对中层弃煤及顶底板应力分布的影响...................................23 万方数据 太原理工大学硕士研究生学位论文 X 3.2.2 上部煤层开采对中层弃煤应力分布的影响...................................................26 3.3 中层弃煤应力场的下位层间距效应.........................................................................27 3.3.1 中层弃煤应力集中系数的层间距效应...........................................................28 3.3.2 中层弃煤卸压区宽度的层间距效应...............................................................29 3.3.3 中层弃煤应力集中区宽度的层间距效应.......................................................31 3.4 不同上位层间距条件下中层弃煤的应力分布特征.................................................32 3.4.1 下部煤层开采对中层弃煤应力分布的影响...................................................32 3.4.2 上部煤层开采对中层弃煤应力分布的影响...................................................33 3.5 中层弃煤应力场的上位层间距效应.........................................................................34 3.6 本章小结.....................................................................................................................36 第四章第四章 层间距层间距对对复合残采区中层弃煤移动变形的复合残采区中层弃煤移动变形的影响影响.................................................... 37 4.1 概述.............................................................................................................................37 4.2 不同下位层间距条件下中层弃煤的变形特征.........................................................37 4.2.1 下部煤层开采对中层弃煤及顶底板移动变形的影响...................................37 4.2.2 上部煤层开采对中层弃煤移动变形的影响...................................................40 4.3 中层弃煤移动变形规律的下位层间距效应.............................................................43 4.4 不同上位层间距条件下中层弃煤的变形特征.........................................................46 4.4.1 下部煤层开采对中层弃煤移动变形的影响...................................................46 4.4.2 上部煤层开采对中层弃煤移动变形的影响...................................................46 4.5 中层弃煤移动变形规律的上位层间距效应.............................................................48 4.6 本章小结.....................................................................................................................50 第五章第五章 层间距对复合残采区中层弃煤层间距对复合残采区中层弃煤围岩围岩结构形式的影响结构形式的影响............................................51 5.1 概述.............................................................................................................................51 5.2 柱式采空区顶板运动过程.........................................................................................51 5.3 中层弃煤围岩结构的下位层间距效应.....................................................................52 5.3.1 下部煤层开采对中层弃煤围岩结构的影响...................................................52 5.3.2 上部煤层开采对中层弃煤围岩结构的影响...................................................55 5.3.3 中层弃煤开采采场结构形式演化规律...........................................................57 5.4 中层弃煤采场岩层结构的上位层间距效应.............................................................58 万方数据 太原理工大学硕士研究生学位论文 XI 5.4.1 上部煤层开采对中层弃煤围岩结构的影响...................................................58 5.4.2 中层弃煤开采采场结构演化规律...................................................................59 5.5 本章小结.....................................................................................................................62 第六章第六章 层间距对复合残采区中层弃煤可采性的影响层间距对复合残采区中层弃煤可采性的影响........................................................ 65 6.1 概述.............................................................................................................................65 6.2 复合残采区中层弃煤开采的临界下位层间距.........................................................65 6.2.1 下控制层位置的判别.......................................................................................65 6.2.2 控制层位置判别的层间距效应.......................................................................71 6.2.3 临界下位层间距的确定...................................................................................72 6.3 复合残采区中层弃煤开采的临界上位层间距.........................................................74 6.3.1 上部煤层煤壁处的塑性区宽度.......................................................................74 6.3.2 上位层间岩层的破坏范围...............................................................................76 6.3.3 临界上位层间距的确定...................................................................................77 6.4 “上垮-下柱”复合残采区中层弃煤可采性判定的层间距效应.................................78 6.4.1 层间距对复合残采区层间岩层结构形式的影响...........................................78 6.4.2 基于层间距的中层弃煤可采性判定方法.......................................................79 6.5 本章小结.....................................................................................................................81 第七章第七章 结论与展望结论与展望.............................................