近浅埋薄基岩煤层开采隔水层破坏机理研究

发布时间：2018-09-04 18:42

【摘要】：在我国的陕西榆林地区蕴含大量煤炭资源、煤层埋深较浅、赋存条件稳定,已经成为我国煤炭开发的重点区域,但伴随着煤层的开采将会破坏浅层含水层,进而引起地下含水层水位下降、泉水、湖泊干涸、川河基流量减小乃至断流,导致区域生态平衡破坏和地表生态环境恶化、沙漠扩展等一系列无法修复的严重环境问题。因此,薄基岩浅埋煤层的最大开发技术难点是怎样安全开采煤炭资源的同时最大限度的保护水资源,达到“保水开采”的目的。但是因薄基岩的厚度不同,导致导水裂隙带发育的高度也有所不同,因此分为典型浅埋煤层和近浅埋煤层。本文结合榆阳矿区主采煤层3煤来进行研究近浅埋煤层采动过后导水裂隙带发育高度。榆阳煤矿#3号煤层工作面厚度在3.2-3.9m之间,煤层赋存于侏罗系中统延安组,埋藏深度约为157m左右,煤层倾角一般平均为0.5°～1°,煤层平均厚度3.5m,赋存较为稳定,结构简单。研究区内地质构造简单,水文地质条件中等,地面地势较为平坦,第四系风积沙层厚20m左右,具有较好的开采条件。但矿区紧邻毛乌素沙漠南缘,东部基本被沙漠滩地覆盖,西部地貌为半固定沙丘状,沙漠覆盖率达到70%以上。区域内降雨量稀少,地下水资源较为贫乏,生态环境非常脆弱,而浅部煤层开采会直接影响到含水层,不仅会直接造成矿井溃水危害,还会破坏可贵的水资源。因而,研究近浅埋煤层导水裂隙带发育的高度对保水开采的成败尤为重要。论文在分析厚风积沙近浅埋薄基岩煤层开采时,采用理论分析判断关键层所在位置,并结合采动后岩层内部移动变形规律,建立出地表最大下沉量和覆岩导水裂隙带高度与覆岩拉伸变形量之间的定量关系,给出他们之间的定量关系,推导了岩层层向拉伸变形的计算公式,从而给出导水裂隙带高度理论预测的新方法。并结合实验室相似模拟实验以及计算机数值模拟软件分别确定了煤层开采后覆岩导水裂隙带发育高度,对比分析理论计算结果、模拟实验结果与数值模拟结果,三种不同方法所获得的结果基本一致,从而验证了理论计算结论的可靠性,研究成果为保水开采理论计算方法提供了新的方向。
[Abstract]:In Yulin area of Shaanxi province, there are a lot of coal resources, the coal bed is shallow, the condition of occurrence is stable, it has become the key area of coal exploitation in our country, but with the mining of coal seam, it will destroy shallow aquifer. Then it causes the groundwater level to fall, the spring water and lake to dry up, the flow of the river base to decrease or even to stop, which leads to the destruction of the regional ecological balance and the deterioration of the surface ecological environment, and a series of serious environmental problems which cannot be remedied, such as the expansion of the desert, and so on. Therefore, the biggest technical difficulty of shallow coal seam exploitation of thin bedrock is how to exploit coal resources safely and protect water resources to the maximum extent, so as to achieve the goal of "water conservation and mining". However, because of the thickness of thin bedrock, the height of water conduction fracture zone is different, so it can be divided into typical shallow coal seam and near shallow buried coal seam. In this paper, the development height of water-conducting fissure zone in near shallow coal seam after mining is studied in combination with 3 coal in main mining seam of Yuyang mining area. The thickness of No. 3 coal seam in Yuyang coal mine is between 3.2-3.9 m, the coal bed is located in Yanan formation of Middle Jurassic, the buried depth is about 157m, the average dip angle of coal seam is 0.5 掳/ 1 掳, and the average thickness of coal seam is 3.5 m. In the study area, the geological structure is simple, the hydrogeological condition is medium, the surface topography is relatively flat, the thickness of the Quaternary aeolian sand layer is about 20m, and the mining conditions are good. But the mining area is close to the southern edge of Maowusu desert, the eastern part is basically covered by desert beach, the western geomorphology is semi-fixed sand dune, the desert coverage rate is over 70%. The rainfall in the area is scarce, the groundwater resources are relatively poor, and the ecological environment is very fragile. The shallow coal seam mining will directly affect the aquifer, which will not only directly cause the mine water burst harm, but also destroy the valuable water resources. Therefore, it is very important to study the development height of water conduction fracture zone in near shallow coal seam. In this paper, when mining thick eolian sand near shallow and thin bedrock coal seam, the position of key strata is judged by theoretical analysis, and combined with the law of internal movement and deformation of strata after mining. The quantitative relationship between the maximum subsidence of the surface and the height of the overburden water-conducting fissure zone and the overburden tensile deformation is established, the quantitative relationship between them is given, and the formula for calculating the tensile deformation of the strata is derived. A new method for predicting the height of the water-conducting fracture zone is presented. In combination with the laboratory simulation experiment and the computer numerical simulation software, the height of the overburden water conductivity fracture zone after coal seam mining is determined, and the theoretical calculation results, the simulation experiment results and the numerical simulation results are compared and analyzed. The results obtained by the three different methods are basically consistent, which verifies the reliability of the theoretical calculation conclusion. The research results provide a new direction for the theoretical calculation method of water conservation mining.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD823.8

【参考文献】