【作者】 邵晓宁；

【导师】 徐颖； 傅菊根；

【作者基本信息】 安徽理工大学 ， 安全技术及工程， 2014， 博士

【摘要】 煤矿综采工作面煤层上覆岩层为厚硬顶板时,采面向前推进的同时,由于厚硬顶板的力学性能及采场布置等特点,易形成采空区悬顶面积增大,常常会出现综采工作面顶板难以自然垮落,并使得瓦斯在采空区积聚。大面积采空区顶板长时间不垮落,将导致工作面控顶区内压力高度集中,造成综采面支护结构破坏,给安全生产带来极大的威胁。同时,大面积悬顶出现突然垮落时会产生强烈动载荷,损坏或推倒工作面的支架,造成工作面垮冒事故；另外极易形成破坏性巨大的飓风和冲击地压,在飓风气浪所经过之处,其强烈的冲击动压时常会摧毁采面及其邻近巷道中的支架、风门和砖墙密闭等设施,甚至翻倒矿车,造成严重的设备损坏和人员伤亡,易造成老塘内的瓦斯瞬间涌出,引起瓦斯超限甚至造成瓦斯爆炸等重大安全事故,给国家和企业造成重大经济损失,是煤矿安全生产顶板事故中极为严重的事故之一在查阅大量国内外相关文献的基础上,论文通过理论分析、模型试验和数值模拟及现场试验相结合的研究方法,对综采工作面厚硬砂岩顶板断裂规律和深孔爆破超前弱化进行了深入的研究。建立顶板来压步距的岩板计算模型,分析了开采过程中顶板垮落过程,得到了厚硬砂岩顶板破断规律以及破断过程中围岩的应力、位移分布特征。在炮孔不耦合装药孔壁压力计算的基础上,从柱状装药结构爆破破岩机理和爆破断裂成缝机理两个方面,分析柱状装药爆炸后岩体内应力传播、裂纹扩展规律。在此基础上,结合爆破振动测试,计算顶板超前深孔爆破岩体损伤范围。基于ABAQUS动力有限元软件,建立了砂岩顶板深孔爆破岩体力学模型,研究不同地应力时岩体内爆炸应力场分布和裂纹扩展特征,分析了初始地应力对爆炸应力场与裂纹扩展的影响。根据试验工作面地质特征和现场条件,进行厚硬砂岩顶板深孔爆破超前弱化现场试验,形成一套合理可行的顶板超前弱化爆破施工工艺。论文的主要研究工作及成果如下：根据综采面采煤过程中,支架后空顶的厚硬顶板的特点,建立了四边固支的薄板力学模型,推导出顶板初次垮落步距公式,得到顶板初次垮落步距。厚硬顶板初次断裂后,随着工作面的推进,建立了厚硬顶板的悬臂岩梁力学模型,将简化后的厚硬顶板不同上覆岩层的载荷带入后,可得到工作面顶板初次垮落步距与周期来压步距。以新集二矿210108工作面地质特征、工程地质特征和开采技术条件为基础,根据相似原理,建立了相似模型,进行了相似模型材料实验,确定了相似材料的配比,研究了开采过程中顶板垮落特征、断裂岩梁波及范围及运动发展规律、岩体内应力分布规律。得出了顶板最大位移发生在工作面中部,工作面两端位移小于中部,出现了明显的垮落滞后,因此会造成工作面中部支架压力大于上下部。采用ABAQUS有限元软件,对不同初始地应力条件下单孔和双孔深孔爆破时炮孔周围应力分布特征和裂纹扩展进行了数值模拟分析,结果表明：裂隙区半径随着初始地应力的增大而减小,意味着高应力条件下岩石相对难爆；爆生裂纹的扩展方向与侧压系数的大小有关,较大初始应力方向上的裂纹长度相对较短；双炮孔爆破时,由于初始地应力对裂纹扩展起削弱作用,有地应力作用的两个炮孔间裂纹扩展长度比无地应力作用时短。因此,在进行深部岩体爆破参数设计时,宜适当减小炮孔间距以利于裂纹在炮孔间贯通。结合新集二矿210108综采工作面工程实际,根据现有工作条件和地质条件,确定顶板深孔爆破超前弱化合理的循环步距为30.0mm；确定了超前深孔预裂爆破方案及合理参数,提出了顶板深孔爆破超前弱化的工艺流程。为评价深孔爆破效果,为以后支架工作阻力确定、爆破参数优化提供基础,根据综采工作面现场情况,进行矿山压力的现场测试和分析。测试结果表明：老顶的周期垮落步距平均为19.08m,而未采用松动爆破时工作面周期来压步距平均为24.6m。矿压观测期间,工作面支架工作阻力基本处于正常范围。工作面支架支护强度较均匀,没有出现大的应力来压现象。工作面煤壁完整,基本无片帮冒顶现象。工作面周期来压压力偏小,工作面有部分位置基本没有明显的来压现象,验证了该技术的有效性。更多还原

【Abstract】 Fully mechanized working face roof often be difficult to caving naturally, during longwall mining under the hard rock roof; with working face propelling, goaf roof hanging area increases gradually, cause gas accumulation in goaf. Large aceage goaf roof does not collapse during a long time also will make stress concentration in working face roof area, causes supporting structure damage, bring huge threat to production. At the same time, if the large overhang roof suddenly caving, strong dynamic load caused by rock broken can make a large number of supporting damage or knocking down, cause catastrophic collapse accidents of mining face; it also can easy to form damaging hurricanes and huge impact ground pressure, the hurricane wave often destroy facilities of working face and its adjacent roadway, such as supporting, air door and brick wall, even make the car overturned, orbital bending, caused serious damage and heavy casualties of personnel, and easy to make the gas accumulated in goaf instantaneous emission, cause serious accident.On the basis of a large number of domestic and foreign related research literatures, this article through theoretical analysis, model testing, numerical simulation and field testing, roof rupture law and deep hole advance blasting for thick and hard sandrock of full mechanized working face was researched. Through establishment of rock plate calculation model for roof weighting interval, mining roof caving process was researched, analyse roof breaking laws and stress and displacement distribution characteristics of rock. On basis of hole wall pressure calculation of decouple charge, with two aspects of column charge blasting mechanism and rock fracture blasting mechanism, stress propagation and law of crack propagation in rock mass was analyzed. Based on finite element software ABAQUS, rock mass mechanics model of deep hole blasting in sandstone roof is established, study blasting stress field distribution and crack propagation characteristics of different initial ground stress, influence of initial ground stress to crack propagation is analyzed, According to the field geological characteristics and site conditions, great thickness sandstone roof deep hole blasting advanced weakening field testing carried out, formaed a set of feasible roof advanced weaken blasting construction techniques. Main research work and achievements of paper are as follows: Through analysis lower and upper parts of cut drilling geological data and theoretical calculation, four edges clamped thin plate mechanics model is established, first caving space formula of roof is derived, Get first caving space of roof; after hard roof first caving, rock beam mechanics model of roof is established. First caving space and periodic caving space of roof calculated by three methods are equivalence. Model test and numerical simulation also shows that stress concentration in all parts of working face, and formed a certain degree of pressure relief in the working face overburden rockmass.Stress concentration maximum value occurrs in central part of working face, followed by upper part of working face, lower part is least. Maximum displacement of roof occurs in the middle part of working face, displacement of two-terminal is less than the central; there is an obvious caving lag,, thus causes support pressure of central part is greater than in top and bottom.According to the results of rock physical and mechanical performance test, stress distribution around the hole and crack propagation of single and double hole blasting under different initial geostress conditions are analyzed by finite element software ABAQUS, the results show that: with the increase of initial ground stress, fracture zone radius reducing, rock blasting is relatively difficult; direction of main crack extension is related to the size of the lateral pressure coefficient; the smaller the initial stress on the direction, crack length is relatively short; during double shot blasting, due to weaken the effect of initial ground stress, crack length with ground stress between two hole is shorter than length without ground stress.Therefore, in deep rock mass blasting parameters design, hole spacing should be reduce.Combination working face of210108in Xinji Coalmine, according to the current working and geological conditions, reasonable space for roof advanced caving deep hole blasting is30.0m; roof advanced caving deep hole blasting scheme and parameters are determined, put forward roof advanced caving deep hole blasting process. For evaluation of deep hole blasting effect, provides basis for support working resistance determination, blasting parameters optimization, mining pressure field testing and analysis is did according to the site conditions. The testing results show that the original roof caving average space is19.08m, which is about24.6m without loose blasting. During mineral pressure observation, working face support working resistance was basically normal range. Support intensity is relatively uniform, no large stress to compressive phenomenon. Working face of coal wall is integrity, no bond andcaving, and pressure of periodic weighting lower than average value, almost no obvious weighting phenomenon, verifies effectiveness of proposed technique.更多还原