【作者】 谢东海；

【导师】 冯涛；

【作者基本信息】 湖南科技大学 ， 采矿工程， 2007， 硕士

【摘要】 急倾斜中厚—厚煤层巷道放顶煤采煤法的关键问题主要有四个:顶煤可放性的影响因素及评价、放煤巷道的布置与维护、顶煤破碎机理、工艺参数等。以多个矿井的工业性试验为基础,采用灰色系统理论、模糊数学方法对顶煤可放性的影响因素与评价进行分析和计算,通过筛选各种指标,选取煤层强度、开采深度、煤层厚度、煤层倾角、煤层顶底板岩层、煤层夹矸和安全条件等七项自然指标十二个二级指标进行分析和计算,得出各项指标与顶煤可放性关联度从大到小的顺序为:煤层强度、煤层倾角、煤层厚度、开采深度、煤层夹矸、安全条件和煤层顶底板岩层。同时,通过计算和比较,将顶煤可放性分为五类:可放性好(Ⅰ)、可放性较好(Ⅱ)、可放性一般(Ⅲ)、可放性较差(Ⅳ)、可放性差(Ⅴ),可据此判断顶煤的可放性。采用弹塑性理论对顶煤应力环境与变形进行分析,认为顶煤受力主要来自煤层与顶板的重力和放顶煤形成的集中应力,水平地应力与瓦斯压力均对顶煤的破碎产生重要影响。计算的极限平衡带高度与现场深基点位移测试数据基本一致,顶煤应力极限平衡带的高度与顶煤破碎及可放性相关,极限平衡带高度大,则顶煤破碎及可放性差;反之,极限平衡带高度小,则顶煤破碎及可放性好。放煤巷道与放煤小眼施工时的顶煤应力和位移变化,采用FLAC软件进行数值模拟,结果表明,放煤巷道和放煤小眼施工扰动时产生的塑性区和塑性破坏等均出现在巷道的肩部和支架的扎脚处,在生产期间应进行重点维护;巷道围岩的位移迹线和主应力均有利于顶煤的变形破碎。顶煤破碎机理分析时,采用弹塑性理论分析顶煤走向的变形破碎过程及顶煤冒落的主要因素;顶煤沿走向的破碎是由于顶煤中部的拉应力超过煤体的抗拉强度所致,顶煤出现“冒落—裂隙带上移—新的冒落—裂隙带进一步上移”的破碎过程,顶煤的冒落与煤体的力学性质及节理裂隙发育程度具有较大的相关性。顶煤沿倾向的变形破碎过程通过非连续介质理论和模拟计算软件(UDEC)进行数值模拟,分析顶煤沿倾向变形破碎的过程和空间形态;顶煤沿倾斜方向在不同冒落高度的力学特性和空间形态基本一致,冒落空间形态具有成拱性,即形成一个“顶板—煤层—底板”的非对称拱型力学结构,拱顶向顶板方向偏移;顶煤和围岩的破坏过程大致分为四个区:顶煤放出区、沿底滑落区、顶板离层破坏区和煤岩滞后冒落区等,煤层顶底板的变形较小,主要是冒落的顶煤给顶底板岩层有一个支撑作用。将突变理论用于顶煤破碎冒落机理分析,建立项煤破坏失稳的尖点突变模型,假设顶煤破碎是受节理裂隙的弱面影响而形成的,得出顶煤破碎冒落的判据为顶煤裂隙面内弹性核区介质的刚度与屈服带内介质的刚度之比,即刚度比。在刚度比小于1时,顶煤弹性核区段的刚度越小、屈服段刚度越大,越易于发生顶煤滑移突变失稳,从而形成破碎冒落。基于计算机模拟的放矿理论对于项煤生产各工艺参数的优化,可以提高顶煤的回收率和降低含矸率。放煤顺序设置合理可以保持顶煤与矸石接触面近水平下移;分段高度在不同煤层厚度时,其有效范围将不同;放煤口间距的大小与顶煤回收率有密切的关系,间距小时,顶煤回收率高,但间距过小会增加生产管理的难度;顶煤含矸率的适量增加可以提高顶煤的回收率。因此,急倾斜中厚—厚煤层巷道放顶煤采煤法的关键问题研究,对完善和推广这一开采方法具有较大的理论意义和实际意义。更多还原

【Abstract】 There were the mainly four key problems on roadway caving mining method of steep inclined medium-thickness seam, which were top coal falling capability and its evaluation, caving roadway layout and maintenance, the top coal broken mechanism and process parameters.Based on the industrial tests of seveal mines, top coal falling capability was analyzed and evaluated by the gray system theory and fuzzy mathematical method. The correlation of indicators and the top coal falling capability is also analyzed and calculated with 12 second indicators and 7 natural indicators. The indicators were seam strength, mining depth, seam thickness, seam dip angle, the roof and floor rock strata, sandwiched rock and safety conditions etal, subdivided in the following order: seam strength,seam dip angle, seam thickness, mining depth, sandwiched rock, safety conditions and the roof and floor strata. Meanwhile, the top coal falling capability is divided into five categories by calculated and comparatived : falling capability good (Ⅰ), falling capability better (Ⅱ), falling capability fair (Ⅲ), falling capability poor (Ⅳ), up poor (Ⅴ). The top coal falling capability can be judged by these indicators.Top coal stress environment and deformation is analyzed by elastic-plastic theory and its simulation software (FLAC). The result shows that the main force of top coal from gravity of top coal and concentrated stress of roof. Meanwhile, the level stress and methane pressure on the top coal to broken coal play a major role. The calculated height of limit equilibrium is consistented with field test data of deep displacement. The limit balanced height of top coal stress top is relevanted with coal caving. The more carshed the broken and caving of the top coal is, the more increased the limit balance height increases. Insteadly, the top coal broken and caving is good with limit equilibrium height decreasing. Stress and displacement of caving roadway and caving chute construction disturbance is simulated by FLAC software of numerical model. The plastic area and plastic damage of caving roadway and caving chute appeared in the roadway shoulder and support-foot-binding is caused by construction disturbance. Displacement trace and main stress of roadway rock will be conducive to the top coal broken.According to the top coal broken mechanism, the broken process of top coal and main factors of top coal caving are analysied by plasticity theory. Top coal broken along the direction of coal seam is because of the tensile stress of central part of the top coal over the tensile strength of coal. Top coal broken is represented as a process of "falling-shift fracture belt-new falling-fracture zone further upward". Top coal broken is greater relevaned with coal mechanical properties and the joints and fractures. Caving deformation and broken process along the dip direction of coal seam are numerically simulated by non-continuum theory and simulation software (UDEC). The broken process and space shape of the top coal crusher deformation along dip of coal seam are analyzed. Space shape of the top coal with arch form, or the formation of a "roof-seam-floor" asymmetrical mechanical arch structure, vault of caving arch to shift direction of coal seam roof. The destruction process of top coal and rock can be divided into four zones. They are the top coal caving area, slide area along the bottom of floor, damaged area of roof separation,coal and rock falling area backward. Deformation of seam roof and floor is small and mostly falling to the caving roof and floor rock as a supporting role.the catastrophe theory is used to analyse the study of top coal broken mechanism. Top coal is destructed by weak of joints and fissures. The cusp catastrophe model of top coal instability is established by the catastrophe theory and reached the criterion of top coal caving that is ratio of stiffness of top coal fissures plane elastic nucleus medium and stiffness of yield zone medium, which is stiffness ratio. When the stiffness ratio is less than 1, the smaller top coal elastic nucleus medium stiffness show, the greater the yield stiffness, more prone to mutation top coal crusher slip instability.Based on the drawing theory of computer simulation to produce top coal process parameters are optimized in order to enhance the top coal recovery rate and to decrease top coal gangue rate. The recent levels is moving down on contact of top coal and gangue by caving orders . Sublevel height and thickness of the coal seam is correlated. Seam thickness increasing decreases sublevel height. Caving chute distance and top coal recovery are closely related. Smaller the distance , higher top coal recovery rate. The gangue of the modest increasing in the amount can increase the recovery rate of the topcoal.The key problems was studyed on roadway caving mining method of steep inclinedmedium-thickness seam. It is of practical and theoretical significance in application and dissemination of the mining method.更多还原