【作者】 解盘石；

【导师】 伍永平；

【作者基本信息】 西安科技大学 ， 采矿工程， 2011， 博士

【摘要】 大倾角煤层是指埋藏倾角为35°～55°的煤层,开采难度大,覆岩结构复杂,“支架-围岩”系统作用与一般倾角煤层差异大,因此,研究大倾角煤层长壁开采覆岩空间结构及其稳定性问题对丰富该类煤层开采理论和指导现场实践均有重要意义。大量的现场实践、实验研究和理论分析表明:大倾角煤层走向长壁工作面开采中,沿倾斜方向矿压显现呈现出“先中部”、“次上部”、“再下部”的基本特征,具有时序性。直接顶、老顶及高位岩层的运移规律具有时序性和不均衡性。倾斜方向中、上部区域内“三带”特征明显,且层位较高;倾斜下部区域内的顶板岩层没有明显的“三带”特征或“三带”形成的层位较低且不完整。大倾角煤层长壁工作面倾斜方向上的顶板以倾斜砌体结构形式存在;沿工作面倾斜方向中上部为倾斜砌体结构活跃区,中部偏下区域为过渡区,倾斜下部区域为稳定区。同时,在采场高位岩层中存在非对称“壳体结构”,“壳体结构”大小主要取决于工作面上覆岩层岩性特征和开采空间大小等因素。倾斜砌体结构与非对称“壳体结构”是大倾角煤层采场特有的空间结构,二者的稳定是保证“支架-围岩”系统稳定性的关键。大倾角煤层长壁采场顶板倾斜砌体结构与支架的相互作用可分为正压、倾向挤压、反倾向挤压、后推和走向挤压型,其易造成支架发生挤压型失稳、下滑失稳、倾倒失稳。大倾角煤层采场壳体局部破坏是壳体结构失稳的主要诱导因素,其失稳模式主要有:以拉伸破坏为主的壳顶失稳,以压剪破坏为主的壳肩失稳,以压剪、拉伸破坏共同作用的壳基复合失稳。大倾角煤层长壁开采覆岩空间的承载结构是指采场空间上覆未破坏的“壳体”和破坏的“倾斜砌体”共同组成的结构,其中“壳体”对“倾斜砌体”的挤压与施载作用,“倾斜砌体”对“壳体”具有挤压与约束作用,上覆“壳体”与“倾斜砌体”的铰接作用降低了覆岩“壳体结构”失稳对工作面的冲击作用。承载结构失稳类型可划分为下压型失稳、推垮型失稳及复合型失稳,可以利用失稳系数ζ大小来描述失稳的可能性。利用能量守恒原理与砌体梁理论对承载结构稳定性进行了分析,给出了工作面上方“壳体结构”破坏对支架的作宏观作用力,并得出了在其作用下承载结构发生下压型失稳、顺向推垮、逆向推垮、走向推垮、复合型失稳的判定条件。根据现场实践经验和实验室研究结果,运用大倾角煤层长壁开采覆岩结构稳定性理论对25112工作面覆岩结构进行了分析,提出了顶板预爆破方案及支护系统防倒防滑措施等,工业性试验表明,理论和实验分析符合现场实际,取得了良好的技术经济效益。更多还原

【Abstract】 The steeply dipping seam is defined by the coal seam a pitch between 35°~55°and has complex occurrence conditions. The reaction of the overburden structure and support–surrounding rock system in the steeply dipping seam to mining is very different from that in flat or moderately pitched coal seam. Studies on the structural stability in the overburden around the mining face in steeply dipping seam has great significance to enrich the practice and theory in mining the steeply dipping seam.Numerous past practices, experimental research and theoretic analysis indicate that the strata movement occurs in the middle of working face first, then at the top and lastly at the bottom along the seam inclination direction. Such sequential changes and imbalance features of failure and strata movements occur in the immediate roof, main roof and top strata. The“Three-zones”features are obvious in middle and top areas along inclination direction at a higher horizons. No intact“three-zones”can be found in the bottom area.Incline masonry structure is formed at the roof in working face along the inclination direction. There is incline masonry structure active region in middle and top areas along the inclination direction, and a transition area in the centre and lower areas, and stability region at the bottom. Asymmetrical“shell structure”is formed at the top strata of mining stope and its magnitude is mainly determined by the mechanical characteristic of working face overburden strata, mining room size and so on. The incline masonry structure and asymmetrical“shell structure”are the special structures for minig steeply dipping seam. Their stability dedicates rational strata control measures to choose.The interaction between support and incline masonry structure can be divided into uprightness-pressing, inclination-pushing, anti-inclination-pushing, back-pushing and strike-pushing functions. These compressive actions can cause stability supports problems to face, downslide-stability, inclination-instability, and concluded six instability criterions. Localized instability of shell structure is the main factor to lead the overall structural instability in the stope. The instability modes are followed: the shell roof instability took tensile destruction as the predominent way, shell shoulder instability is initialized by compression-shear failure predominently,and shell bases composite instability occurs in tensile and compression-shear modes predominently.The complete“shell”and destruction“incline masonry”are interpreted as load-bearing structure around the coal mining face in steeply dipping seam. Between the“incline masonry”has extrusion and constraint effect on“shell”, and“shell”has extrusion and loading impact effect on“incline masonry”, the instability impacting action of“shell structure”to working face is relieved by the hinge function of“shell”and“incline masonry structure”. Load-bearing structure instability types can be comprised of uprightness-pressing instability, pushing instability, composite instability and so on. The instability possibility can be described by the instability coefficient, the macroscopic stress F of“shell structure”to working face supporting and stability of load-bearing structure are concluded by using energy conservation principle and masonry beam theory, and also five criterions are obtained: uprightness-pressing instability, forward pushing instability, reverse pushing instability, strike pushing instability and composite instability.According to field practices and experimental research, the overburden structure working face 25112 is analyzed by the theory of overburden structure stability around the coal face. The roof pre-blasting scheme and the support system anti-skid measures are recommended. Field tests show that the theory and the experimental analysis matched well. Good technical and economic benefits are realized.更多还原