榆神矿区浅埋煤层减水开采中预疏放标准确定方法

榆神矿区地处干旱半干旱地区,生态环境十分脆弱。疏放水是榆神矿区顶板水害防治的主要手段,但过度疏放不仅增加矿井排水负担,而且不利于保护浅层地下水资源。因此,在确保防治水安全的前提下,计算预疏放残余水头、确定预疏放阶段和回采阶段第四系松散含水层漏失量,从而实现总漏失量最小是煤炭减水开采中的重点研究问题之一。以榆神矿区锦界煤矿为例,在分析井田含、隔水层赋存特征的基础上,建立了煤层开采的2种充水模式,并对顶板含水层进行了富水性分区;以矿井涌水量实测数据为基础,分析了涌水量变化规律及其构成比例;采用Drain边界刻画多工作面连续回采内边界,建立了锦界煤矿采掘扰动条件下地下水流数值模型,研究了两种充水模式下预疏放残余水头在不同工况下的第四系松散含水层总漏失量变化规律,确定了工作面预疏放结束标准。结果表明:锦界煤矿煤层顶板为典型的沙(层)-土(层)-基(岩)型结构,主要充水水源为风化基岩水,主要充水模式为土层未缺失风化基岩充水型及土层缺失风化基岩和松散层混合充水型。采用GIS多元信息融合技术划分的井田富水性分区结果显示,相对强富水区位于井田二盘区局部地段、三盘区和四盘区大部分地段,与现场实际基本一致。矿井疏放水量与工作面回采残余涌水量曲线变化趋势基本一致,各占矿井涌水量的50%左右。通过数值模型计算得出两种充水模式下工作面预疏放结束标准为将充水含水层疏放至煤层底板以上15~20 m,保留一定的残余水头可进行回采,无需继续疏放。此时,第四系松散含水层水资源总漏失量最小,可起到减水采煤的作用。研究成果为榆神矿区浅埋煤层提供了“减水开采”的新思路。

Method of determining of pre-drainage standard in water-decrease mining of shallow seam in Yushen mining area

Yushen mining area is located in an arid and semi-arid area,and its ecological environment is very fragile.Drainage is the main method to prevent and control the roof water disaster in Yushen mining area.Excessive drainage increases the burden of mine drainage.In addition,it is not conducive to protect the shallow groundwater resource.Therefore,under the prerequisite of preventing and controlling water hazards,it is an important subject in water-decrease mining to calculate the pre-drainage residual water head,and determine the amount of water leakage of Quaternary unconsolidated aquifer during pre-drainage and mining,in order to minimize the amount of water leakage of Quaternary in the working face.Taking Jinjie coal mine as an example in this paper,based on the analysis of the occurrence characteristics of aquifer and aquiclude,two water filling modes of coal mining were established.Furthermore,the water-abundance of roof aquifer was divided.Based on the measured data of mine water inflow,the changing rule and component proportion ratio of water inflow were analyzed.The inner boundary of multiple working faces of continuous mining was described by drain boundary,and the numerical model of groundwater flow under excavation disturbance in Jinjie coal mine was established.The change rule of the amount of water leakage in Quaternary unconsolidated aquifer under different pre-drainage residual water head conditions of two water filling modes was studied,and the pre-drainage ending standard of working face was determined.The result showed that the coal seam roof of Jinjie coal mine was a typical sand-soil-bedrock structure.The main water filling source was entirely consisted of bedrock water.The water filling mode mainly included two modes:the water filling mode of weathered bedrock without soil layer missing,and the water filling mode of weathered bedrock with soil layer missing mixed with unconsolidated formation.The GIS multi-information fusion technology was used to divide the water-abundance of mine field,and the result showed that the relatively strong watery zone in the mine field was located in some sections of the second panel,the third panel and almost all the sections of fourth panel,which was basically consistent with the actual situation on site.The variation trend of drainage water quantity was basically consistent with that of mining water inflow curve on working face,each accounting for 50%of total mine water inflow.By means of numerical model calculation,the pre-drainage ending standard of working face under two water filling modes was determined to drain the water head until water-filled aquifer was 15 to 20 m above the coal seam floor,a certain residual head can be retained for mining without further drainage.By this time,the amount of water leakage in Quaternary unconsolidated aquifer reached the minimum value,which can play a role in reducing water while mining.The research result provides a new idea for“water-decrease mining”for shallow coal seam in Yushen mining area.