衰老矿区松散含水层下提高残煤资源开采上限研究

Study on Increasing Mining Upper Limit of Residual Coal Resources under Loose Aquifer in Exhausted Mining Area

我国东部衰老矿区浅部松散层普遍发育较厚,为避免松散层水害事故,矿井在煤层露头区普遍留设了防水煤柱,滞留了大量优质煤炭资源。各矿区经过长期开采,浅部松散含水层的水文地质条件发生了重大变化,为回收浅部块段大量残煤资源提供了可行性。针对衰老矿区长期开采条件下水文地质条件发生重大改变的实际条件,通过系统研究并揭示长期开采扰动下松散层水文地质条件全生命周期的演化过程及规律、松散层下—近距离煤层—重复采动条件下覆岩变形破坏过程及规律,在此基础上,提出了松散含水层下开采水文地质条件发生重大改变后残煤资源安全回收的评价方法体系:首先,通过数值模拟精确刻画研究区松散含水层“富水性弱化”的演变过程与规律,系统评价残煤资源回收的水文地质条件;其次,通过数值模拟、相似材料模拟、现场实测及实测数据拟合对比等水文地质决策与综合探查验证的手段分析煤层开采条件下覆岩变形破坏特征及“两带”发育高度,多种方法互相验证以确保评价结果的准确性;最后,利用数据拟合获取的垮落带计算新公式进行煤柱留设优化计算与可行性评价,确保残煤资源的安全回收。利用该评价方法,已在徐州、两淮及鲁西南矿区5座煤矿、13个工作面取得了成功试采并得到工程验证,累计安全回收煤柱资源458万t,经济与社会效益显著,证明衰老矿区松散含水层下提高残煤资源安全开采上限研究方法可行。

The shallow loose layer is generally thick in the exhausted mining area in eastern China.In order to avoid the water disaster of the loose layer,waterproof coal pillars are generally left in the coal seam outcrop area,and a large number of high-quality coal resources are retained.After long-term mining in each mining area,the hydrogeological conditions of shallow loose aquifer have undergone significant changes,which provides the feasibility for recovering a large number of residual coal resources in shallow blocks.In view of the actual conditions of significant changes in hydrogeological conditions under long-term mining conditions in the exhausted mining area,the evolution process and law of the whole life cycle of the hydrogeological conditions of the loose layer under long-term mining disturbance,and the deformation and failure process and law of the loose rock under the loose layer-close coal seam-repetitive mining conditions are systematically studied and revealed.On this basis,an evaluation method system for the safety recovery of residual coal resources after major changes in hydrogeological conditions under loose aquifers is proposed:Firstly,the evolution process and law of the'water-rich weakening'of the loose aquifer in the study area are accurately characterized by numerical simulation.Systematic evaluation of hydrogeological conditions for the recovery of residual coal resources.Secondly,by means of numerical simulation,similar material simulation,field measurement and measured data fitting comparison of hydrogeological decision-making and comprehensive exploration verification,the deformation and failure characteristics of rock and the development height of'two zones'under coal seam mining conditions are analyzed,and various methods are verified to ensure the accuracy of the evaluation results.Finally,the new formula of caving zone calculation obtained by data fitting is used to optimize the calculation and feasibility evaluation of coal pillar retention to ensure the safe recovery of residual coal resources.The evaluation method has been successfully applied to 5 coal mines and 13 working faces in Xuzhou,Huainan and Huainan mining areas,and has been verified by engineering practice.The cumulative safe recovery of coal pillar resources is 4.58 million tons,and the economic and social benefits are remarkable.It is proved that the method of improving the upper limit of safe mining of residual coal resources under loose aquifer in exhausted mining area is feasible.