采空区煤柱下特厚煤层综放采场覆岩结构及运移规律研究

发布时间：2018-06-13 05:41

本文选题：采矿工程 + 采空区煤柱　；参考：《太原理工大学》2017年硕士论文

【摘要】：在煤层开采过程中,需要留设一些保护煤柱维持巷道和顶板的稳定,但是不能否认煤柱是煤炭开采的“万恶之源”。采空区残留煤柱对上导致顶板至地表围岩不均匀沉降,对下引起底板应力非均匀分布。对于下层煤开采而言,煤柱的应力集中对下煤层具有较大的影响。采空区煤柱下层间岩层为30~80m时,对于普通工作面没有明显影响,但是对于14m以上的特厚煤层大采高综放采场影响较为显著。上覆采空区碎裂岩体在底部煤层大范围开挖后,层间岩层自承能力不强,以某种碎裂结构形式传递载荷并作用在下覆基岩上。当基岩不足以形成结构时,上层采空区与下层采空区全贯通,导致工作面出现整体切落式压架事故的发生。煤柱的集中应力作用加剧了这种强矿压显现压架事故的发生。本文以斜沟煤矿13#煤为具体工程背景,综合理论分析、数值模拟、相似模拟以及实测等手段,研究上覆采空区岩层及煤柱变形、运移及破坏特征对下组厚煤层开采影响的煤岩移动规律,动态分析煤岩失稳灾变过程,并寻求控制煤岩动力灾害的主控煤岩层及结构形成与失稳条件,探索上层采空区煤柱与下层采空区全厚贯通切落压架的条件并建立对应的判断准则,以分析支架工作阻力确定原则和方法。得到以下主要结论:(1)8#煤层采空区主要以两侧采空区煤柱存在为主,煤柱对底板覆岩影响较大。煤柱在顶板载荷的作用下会产生变形破坏,直至丧失稳定性。基于煤柱极限载荷、流变特性和突变理论对煤柱稳定性进行判断,最终求得煤柱的极限宽度为8.9m。小于临界宽度时煤柱完全失稳破坏;大于临界宽度时将产生应力集中。通过理论分析,建立不同的力学模型,对煤柱应力集中下底板的应力传播及破坏深度进行研究。(2)研究特厚煤层综放开采矿压规律,并对初次来压、周期来压垮落特征进行分析,给出破断距计算式。同时利用关键层判断理论,将斜沟煤矿覆岩进行关键层的判定。利用理论分析,对直接顶、基本顶和进出煤柱阶段覆岩的破坏运移过程进行定性分析。(3)对于采空区煤柱下层间岩层为55m的综放工作面,出煤柱阶段覆岩出现整体切落式破坏、会造成工作面压架等灾害。煤柱宽度、煤柱间距以及煤柱密度不同参数条件下,覆岩结构的运移破坏及对底板伏岩的影响程度也不同。不同宽度单一煤柱下,煤柱越宽,对底板伏岩影响程度和区域也越大。对于多煤柱条件下,煤间距在一定范围内,可视为一个整体煤柱;当煤间距等于某个值时,出现临界值点,覆岩结构由煤柱大的一侧决定;当煤间距大于某个值时,形成独立的影响区域。同时依据模拟和试验结果,建立力学模型,对压架机理提出判断准则,并对煤柱影响区域宽度进行预测。(4)对于煤柱下层间距为55m的综放工作面出现压架的问题,主要集中于采空区贯通及出煤柱的位置。通过建立不同条件下的支架围岩结构模型,分析了采空区煤柱下特厚煤层开采的压架机理,得到合理支架工作阻力计算方法。研究表明出煤柱阶段,支架需要27766.4KN的工作阻力才能保证采场围岩安全与稳定。现有支架很难满足如此大的工作阻力,传统只能通过调斜工作面、降低采高、加快推进速度(只采不放)等被动措施保证采场围岩的稳定。(5)提出采用深孔爆破煤柱或主控岩层的方法,通过主动改变围岩结构保证采场围岩的稳定,并通过数值模拟加以初步的验证。
[Abstract]:In the process of coal mining, it is necessary to keep some coal pillars to maintain the stability of the roadway and roof, but it can not be denied that the coal pillar is the "evil source" of coal mining. The residual coal pillar in the goaf leads to the uneven settlement of the roof to the surface rock, and the stress of the bottom floor is uneven distribution. For the lower coal mining, the coal pillar should be used. The stress concentration has a great influence on the lower coal seam. When the lower strata of the coal pillar in the goaf are 30~80m, it has no obvious influence on the ordinary working face, but it has a significant influence on the fully mechanized caving mining in the thick coal seam above the 14m. Some kind of fractured structure conveyed load and acted on the overlying bedrock. When the bedrock was not enough to form the structure, the upper goaf and the lower goaf perforated all through, leading to the occurrence of a holistic shear failure in the working face. 13# coal is a specific engineering background, comprehensive theoretical analysis, numerical simulation, similar simulation and measurement, to study the deformation, migration and failure characteristics of the overlying strata, movement and failure characteristics of the coal and rock movement, dynamic analysis of the catastrophic process of the coal rock instability, and to seek the main coal and rock strata to control the coal and rock dynamic disasters. And the conditions of structural formation and instability, the conditions of the coal pillars in the upper goaf and the full thickness of the lower goaf are explored and the corresponding criteria are established to determine the principles and methods for determining the working resistance of the stents. (1) the main conclusions are as follows: (1) the main coal pillar in the goaf of the coal seam is the existence of the coal pillars in both sides of the goaf, and the coal pillar to the floor overlying rock The influence of the coal pillar on the roof load will produce deformation and failure, until the stability is lost. Based on the ultimate load of the coal pillar, the rheological characteristics and the catastrophe theory are used to judge the stability of the pillar, and the ultimate width of the coal pillar is 8.9m. less than the critical width, and the coal pillar is completely unstable and damaged when the critical width is less than the critical width, and the stress set will be produced when the critical width is larger than the critical width. Through theoretical analysis, different mechanical models are established to study the stress propagation and failure depth of the floor under the stress concentration of the coal pillar. (2) study the ore pressure law of the fully mechanized coal seam fully mechanized coal seam. The determination of the key strata of the mineral overburden is carried out. By using the theoretical analysis, the failure and migration process of the overlying rock in the stage of the direct top, the basic top and the entry and exit of the coal pillar is qualitatively analyzed. (3) for the fully mechanized caving face of the lower strata of the coal pillar in the goaf, the overall tangential failure of the overburden in the coal pillar stage will result in the pressure of the working face and so on. Under the condition of the degree, the spacing of the pillar and the different parameters of the density of the coal pillar, the movement and destruction of the overburden structure and the degree of influence on the bottom of the floor are also different. Under the single pillar of different width, the wider the coal pillar, the greater the influence degree and area to the bottom of the bottom. When the distance of coal equals to a certain value, there is a critical value point. The overburden structure is determined by the large side of the coal pillar. When the coal spacing is greater than a certain value, the independent influence area is formed. At the same time, a mechanical model is established according to the simulation and test results. The criterion for judging the mechanism of the pressure frame is put forward, and the width of the influence area of the pillar is predicted. (4) for the lower layer of the coal pillar. The problem of pressure frame in the fully mechanized caving face with spacing of 55m is mainly concentrated on the position of perforation in the goaf and the position of the coal pillar. By establishing the structure model of the surrounding rock under the different conditions, the mechanism of the pressing of the thick coal seam under the coal pillar in the goaf is analyzed, and the calculation method of the reasonable support force is obtained. The study shows the stage of the coal pillar and the support. The working resistance of 27766.4KN is required to ensure the safety and stability of the surrounding rock of the stope. The existing support is difficult to meet such large work resistance. The traditional passive measures, such as the adjustment of the inclined working face, the reduction of the mining height, the acceleration of the propulsion speed (only not to be released), can ensure the stability of the surrounding rock of the stope. (5) the method of adopting the deep hole blasting coal pillar or the main controlled rock layer is proposed. The stability of surrounding rock of stope is ensured by actively changing surrounding rock structure, and is verified by numerical simulation.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD325

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