浅埋煤层大采高工作面顶板结构及其稳定性研究

发布时间：2018-08-26 18:31

【摘要】：陕北浅埋厚煤层储量丰富,大采高技术应用普遍。随着采高的增大,采用的支架架型不断增大,支护成本不断提高,合理工作阻力确定缺乏科学依据,制约着安全经济开采。研究浅埋煤层大采高工作面的顶板结构及其稳定性,揭示来压机理,确定合理的支架阻力,具有重要的理论和实践意义。本文通过对浅埋煤层矿区采高为4m、5m、6m、6.8m的大采高工作面实测数据分析,得出随着采高的增大,工作阻力不断增大,尤其是采高达到6.8m时,工作阻力急剧增大;动载系数有所增加,总体平缓。通过对三道沟煤矿6.3m大采高和张家峁煤矿6m大采高工作面的物理相似模拟,得出工作面超前支承压力峰值为原岩应力的1.72倍,峰值的影响范围为60~80m,峰值距煤壁的位置约为采高的2倍。随着采高的增大,等效直接顶厚度不断增加。研究发现,等效直接顶厚度的变化是影响大采高顶板结构的主要因素;等效直接顶的破坏形态,对大采高来压特征有明显影响。由于等效直接顶变厚,老顶铰接位置上移,采空区充填不充分,老顶下位关键层沿破断线表现为“斜台阶岩梁”结构,上位关键层为“砌体梁”结构,对工作面来压构成主要影响的是下位关键层结构。根据等效直接顶垮落后充填程度对老顶结构的影响,将等效直接顶分为3种类型,即充分充填型,一般充填型,和欠充填型,并且分析了等效直接顶与采高之比对垮落充填率的影响。针对老顶破断位于煤壁上方和后方的条件,建立了大采高工作面顶板“斜台阶岩梁”结构模型,得出了两种条件下支架工作阻力的计算公式,通过工程实例进行了验证。基于该模型,分析了等效直接顶厚度,老顶岩块长度、老顶关键层厚度、顶板破断角、老顶关键层破断点位置对支架工作阻力的影响,为大采高采场岩层控制提供了依据。
[Abstract]:Shallow and thick coal seams in northern Shaanxi are rich in reserves and widely used in large mining height technology. With the increase of mining height, the type of support frame is increasing, the support cost is increasing, and the determination of reasonable working resistance is lack of scientific basis, which restricts the safe and economic mining. It is of great theoretical and practical significance to study the roof structure and stability of large mining face in shallow coal seam, to reveal the pressure mechanism and to determine the reasonable support resistance. Based on the analysis of the measured data of large mining face with mining height of 4 m ~ 5 m ~ 6 m in shallow coal seam mining area, it is concluded that with the increase of mining height, the working resistance increases continuously, especially when mining height reaches 6.8 m, the working resistance increases sharply and the dynamic load coefficient increases. The overall level is flat. Through the physical similarity simulation of the large mining face of 6.3m height in Sandaogou coal mine and the 6m mining face of Zhangjiaomao coal mine, it is concluded that the peak value of the leading supporting pressure of the working face is 1.72 times of the original rock stress. The influence range of peak value is 60 ~ 80 m, and the position of peak value from coal wall is about 2 times of mining height. With the increase of mining height, the equivalent direct top thickness increases continuously. It is found that the change of equivalent direct roof thickness is the main factor affecting the roof structure of large mining height, and the failure pattern of equivalent direct roof has obvious influence on the characteristics of pressure coming from large mining height. Due to the equivalent direct roof thickening, the main roof hinged up and the goaf filling is not sufficient, the key layer of the main roof and the lower part of the main roof is "inclined step rock beam" structure along the broken line, and the upper key layer is the "masonry beam" structure. The structure of the lower key layer is the main influence to the pressure coming from the working face. According to the influence of the backwardness degree of the equivalent direct roof on the roof structure, the equivalent direct roof is divided into three types, namely, the full filling type, the general filling type, and the underfilled type. The effect of the ratio of equivalent direct roof to mining height on the rate of caving and filling is analyzed. In view of the condition that the main roof break is located on the coal wall and behind the coal wall, the structural model of "inclined step rock beam" of the roof of the large mining face is established, and the calculation formula of the working resistance of the support under two conditions is obtained, which is verified by an engineering example. Based on this model, the effects of equivalent direct roof thickness, main roof block length, roof critical layer thickness, roof breaking angle and the breakpoint position of roof key layer on the working resistance of the support are analyzed, which provide the basis for the strata control in the mining stope with large mining height.
【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】：TD323

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