大倾角松软煤层综放工作面顶煤破坏影响因素与机理研究

发布时间：2018-03-18 14:31

本文选题：大倾角煤层　切入点：放顶煤　出处：《西安科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：大倾角松软煤层综放工作面顶煤破坏影响因素多,机理复杂。回采过程中,顶煤的破碎、漏冒对工作面支护系统稳定性起着决定性影响。研究大倾角松软煤层综放工作面顶煤破坏的影响因素及作用机理对控制工作面“支架—围岩”系统稳定、保证工作面安全高效生产具有重要的指导意义。本文采用数值分析、物理相似模拟实验、理论分析与工程实践相结合的方法对顶煤破坏的影响因素及诸因素对顶煤破坏的作用机理进行了研究,结果表明:不同的煤层倾角、煤层强度、采放比以及支架的反复支撑是顶煤破坏的四个主要影响因素。煤层倾角的增大将使得顶煤破坏程度的区域性特征凸显;煤层强度的降低则会加剧端面顶煤的破坏,扩大破坏范围;随着采放比的增大端面顶煤的变形破坏程度将进一步加剧;支架的反复支撑将使得控顶区顶煤的残余强度急剧下降,破坏为失去宏观力学联系的散体介质。在这四个影响因素中,煤层倾角与煤层强度属内因,支架的反复支撑与采放比设计属外因。顶煤的“施载体”主要是基本顶“结构”与下位载荷层载荷。沿走向基本顶“结构”形式将经历“悬臂梁”→“砌体梁”→“低位小结构”的转化过程。工作面推进过程中,顶煤受到的顶板压力主要由非均衡约束作用下顶板的“低位小结构”失稳与载荷层载荷所提供。受煤层倾角影响,沿倾斜方向“关键层”层位向上迁移导致不同区域顶板“结构”的形成层位与失稳形式不一,进而使得顶煤在不同压力作用下的破坏程度出现区域性差异。当顶煤进入支架上方后,随着围压状态的改变,煤体残余强度迅速降低,此时支架的反复支撑将会对在支承压力下已发生损伤的顶煤造成再次破坏,特别是在煤层松软时,这种破坏的程度更加剧烈,影响范围也更靠近煤壁,易造成顶煤漏冒。当采放比设计过大时,较薄的顶煤抗载能力弱化,在外载作用下更加容易过早地在支架上方破坏为散体介质。上述因素对顶煤的破坏作用在一定条件下耦合叠加,将极大弱化工作面“支架—围岩”系统稳定性,诱发工作面围岩灾害。长山子煤矿1121工作面生产过程中支架的工作阻力分布以及稳定性的特征显现了各影响因素对顶煤的破坏作用,并针对这些破坏作用提出了“大倾角松软煤层综放工作面支护系统稳定性关键控制措施”。
[Abstract]:There are many factors affecting the failure of top coal in fully mechanized caving face with large inclination and soft seam, and the mechanism is complex. In the process of mining, the top coal is broken. The leakage of caving has a decisive effect on the stability of the supporting system of the working face. The factors affecting the failure of the top coal and the mechanism of the failure of the top coal in the fully mechanized caving face with large dip angle are studied, and the stability of the supporting and surrounding rock system of the working face is studied. It is of great significance to ensure the safe and efficient production of the working face. In this paper, numerical analysis and physical similarity simulation experiments are used. The influence factors of top coal failure and the action mechanism of various factors on top coal destruction are studied by combining theoretical analysis with engineering practice. The results show that: different coal seam inclination angle, coal seam strength, Mining caving ratio and repeated support are the four main influencing factors of top coal failure. The increase of coal seam inclination will make the regional characteristics of top coal destruction prominent, and the decrease of coal seam strength will aggravate the destruction of top coal on the end face. The extent of deformation and failure of top coal will be further aggravated with the increase of mining and drawing ratio, and the residual strength of top coal in controlled roof area will be decreased sharply by repeated support of support. Among the four influencing factors, the dip angle of coal seam and the strength of coal seam belong to internal cause. The design of repeatedly supporting and drawing ratio of support is an external cause. The "carrier" of top coal is mainly the basic top "structure" and the lower load layer load. "cantilever beam" will be experienced along the direction of the basic top "structure". 鈫扢asonry beam. 鈫扗uring the working face advance, the roof pressure of the top coal is mainly provided by the instability of the "low position structure" and the load layer load of the roof under the action of unbalanced constraint, which is affected by the inclination of the coal seam, the process of transformation of the "low small structure" in the working face is mainly provided by the "low position small structure" under the action of disequilibrium constraint. The upward migration of the "critical layer" along the inclined direction leads to different cambium and instability of the roof "structure" in different regions. When the top coal enters above the support, with the change of the confining pressure, the residual strength of the coal decreases rapidly. At this time, the repeated support of the support will cause another damage to the damaged top coal under the supporting pressure, especially when the coal seam is soft, the degree of the damage is more severe, and the influence range is closer to the coal wall. It is easy to cause roof coal leakage and caving. When the drawing ratio is too large, the thin top coal anti-load ability is weakened. Under the action of external load, it is easier to prematurely destroy on the top of the support as a granular medium. The above factors are coupled and superimposed on the top coal under certain conditions, which will greatly weaken the stability of the "brace-surrounding rock" system in the working face. The characteristics of working resistance distribution and stability of the support in the production process of 1121 working face of Changshanzi Coal Mine show the destructive effect of various factors on the top coal. The key control measures for the stability of the support system of the fully mechanized caving face in the soft coal seam with large inclination are put forward.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD355;TD323

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