近距离煤层群下保护层开采瓦斯运移规律及抽采研究

发布时间：2018-02-23 19:32

本文关键词： 近距离煤层群下保护层瓦斯运移瓦斯抽采数值模拟　出处：《湖南科技大学》2013年硕士论文　论文类型：学位论文

【摘要】：近距离煤层群下保护层开采条件下工作面瓦斯治理是制约生产安全的难题。本文以贵州盘江精煤股份有限公司金佳矿近距离煤层群下保护层开采瓦斯治理为工程背景，采用现场实测、理论分析、数值模拟等手段，，分析了下保护层开采后上覆岩层的应力分布、移动变形及破坏情况，在此基础上研究了下保护层开采卸压瓦斯运移规律，研究结果如下：（1）分析保护层开采覆岩“三带”的形成，得出11223工作面开采覆岩的冒落带和裂隙带最大高度分别约为6m和15.5m（±4m）。运用弹塑性力学，建立采场上覆岩层力学模型，对11223采空区上方13m处岩梁处应力进行计算，得出离采空区中心0~60内为应力降低区，75~130m范围内则为应力集中区，离采空区中心0~75m范围内均出现了不同程度的下沉。根据瓦斯运移理论分析了11223工作面瓦斯运移动的基本规律。（2）采用FLAC3D数值模拟软件对11223工作面开采过程进行数值模拟，结果表明：下保护层开采过程中，上覆岩层经历了应力集中、应力降低、应力恢复的过程；上覆岩层部分区域产生明显的变形和沉降，随着工作面的推进，沉降范围和程度逐步增大，尤其以采空区中部上覆岩层变形沉降较大，由采空区中部向切眼和工作面煤壁处及两侧煤壁处，变形和沉降量逐步减小；上覆岩层中应力降低区和塑性区在煤层层面的分布为椭圆形；采空区中部及四周分别以拉伸和剪切破坏为主，在采空区上方形成“回”字型围岩裂隙圈。（3）利用FLUENT数值模拟软件分析了U型通风、U型通风+采空区埋管、U型通风+高抽巷及U型通风+高抽巷+采空区埋管四种不同条件下的瓦斯运移规律，结果表明：U型通风条件下工作面瓦斯涌出较大，上隅角瓦斯浓度较高，因此必须增加瓦斯抽采措施；U型通风+采空区埋管条件下更多的瓦斯随抽采风流在回风侧集聚，这就会造成工作面瓦斯涌出增大与上隅角瓦斯浓度升高。U型通风+高抽巷条件下工作面瓦斯涌出得到了一定程度的降低，但是由于高抽巷自身位置的制约，它不能有效抽采采空区下部邻近回风巷一带集聚的高浓度瓦斯，所以依然不能有效解决工作面瓦斯涌出和上隅角瓦斯超限问题。U型通风+高抽巷+采空区埋管可以有效抽采覆岩邻近煤层涌出的高位瓦斯和采空区下部集聚的低位瓦斯，因此能取得较好的瓦斯治理效果。（4）针对近距离煤层群下保护层开采情况，探讨了卸压瓦斯运移与汇集特征，总结了卸压瓦斯抽采的合理方法。根据金佳矿下保护层开采实际情况，制定了U型通风+高抽巷+采空区埋管瓦斯治理方法，现场实测表明瓦斯治理取得了较好的效果。
[Abstract]:It is a difficult problem to control the production safety under the mining condition of the protection layer under the close distance coal seam group. This paper takes the gas treatment under the protection seam group of Jinjia Coal Mine of Guizhou Panjiang Clean Coal Co. Ltd as the engineering background. By means of field measurement, theoretical analysis and numerical simulation, this paper analyzes the stress distribution, displacement, deformation and failure of the overburden strata after the mining of the lower protective layer, and on this basis studies the law of the gas migration in the mining of the lower protective layer under pressure relief. The findings are as follows:. 1) by analyzing the formation of "three zones" of overburden in mining protection layer, it is concluded that the maximum height of caving zone and fissure zone in mining overburden of 11223 face is about 6 m and 15. 5 m (卤4 m) respectively. Using elastoplastic mechanics, the mechanical model of overburden strata in mining stope is established. The stress of rock beam at 13m above the 11223 goaf is calculated, and it is found that the stress concentration area is in the range of 75m ~ 130m from the center of goaf, which is the stress reduction area. According to the theory of gas migration, the basic law of gas transportation and movement in 11223 working face is analyzed according to the different degree of subsidence within 75 m from the center of goaf. (2) the mining process of 11223 face is simulated with FLAC3D software. The results show that the overburden strata undergo the process of stress concentration, stress reduction and stress recovery during the mining process of the lower protective layer; The overlying strata have obvious deformation and settlement in some areas. With the advance of the working face, the settlement range and degree gradually increase, especially in the middle of the goaf, the deformation and settlement of the overlying strata is larger. The deformation and settlement of the coal face and the coal wall are gradually decreased from the middle of the goaf to the coal face, and the distribution of the stress reduction zone and the plastic zone in the overlying strata is elliptical. In the middle of goaf and around the goaf, tensile and shear failure are dominant respectively, and the "return" type surrounding rock fissure circle is formed above the goaf. Using FLUENT numerical simulation software, this paper analyzes the gas migration law under four different conditions: U type ventilation, U type ventilated goaf, U type ventilation high drainage roadway and U type ventilation high drainage roadway, and U type ventilation high drainage roadway. The results show that the gas emission in the working face is larger and the gas concentration in the upper corner is higher under the ventilation condition of U U type, so it is necessary to increase the measures of gas extraction in the U type ventilation goaf under the condition of buried pipe, and more gas accumulates with the suction air flow on the return air side. This will result in the increase of gas emission in the working face and the increase of gas concentration in the upper corner. Under the condition of high ventilation and high drainage in the upper corner, the gas emission of the working face will be reduced to a certain extent, but due to the restriction of the location of the high drainage roadway, It can not effectively extract the concentrated high concentration gas in the lower part of the goaf adjacent to the return air lane. Therefore, it is still unable to effectively solve the problem of gas emission in the working face and gas overrun in the upper corner. U type ventilation and high drainage roadway buried pipe can effectively drain the high level gas emitted from the adjacent coal seam of overlying rock and the low level gas accumulated in the lower part of the goaf. Therefore, better gas control effect can be achieved. In view of the mining situation of the protective layer under the close distance coal seam group, the characteristics of gas migration and collection under the pressure relief are discussed, and the reasonable method of the gas extraction under the pressure relief is summarized. According to the actual mining situation of the protective layer under the Jinjia Coal Mine, The method of gas treatment in the goaf of high drainage roadway with U-type ventilation is established. The field measurement shows that the gas treatment has achieved good results.
【学位授予单位】：湖南科技大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TD712.6;TD823.81

【相似文献】