西部矿区煤水协调开采物理与情景模拟实验研究

Physical modelling and scenario simulation of coal&water co-mining in coal mining areas in western China

针对西部煤炭主产区矿井水保护利用技术难题,以煤水协调开采为基本原则,自主设计了包含实验材料配制系统、模型框架加载系统、水压控制系统、柔性隔离层注浆控制系统、数据采集系统等5部分组成的煤水协调开采物理模拟实验平台;研制出由骨架结构物和胶结物组成的相似材料,其中骨架结构物用于调控相似材料弹性模量,胶结物用于调控相似材料整体强度,经检验,所研制材料的力学和渗流特性均满足相似模拟实验的基本要求;以西部宁东煤田麦垛山煤矿2号煤首采区为研究对象,开展了煤水协调共采物理相似模拟实验研究,工作面回采3~5个周期来压步距后,通过对隔水层进行注浆改造或压裂处理,分析煤水协调开采过程中导水裂隙带高度演化特征、7个测点水流变化情况以及顶板破断特征,研究表明:隔离层压裂改造位置应位于超前基岩顶板扰动范围之外,隔离层注浆改造应在岩层充分压实后(3~5个周期来压后)进行,采用压裂和注浆封堵相结合的工艺手段,隔离了“地下水”向下渗流通道,可以实现地下水原位保护。模拟研究了4种工况条件下人工隔水层的保水作用,首先对2号煤首采区上覆含(隔)水层系统进行数值概化,建立研究区地下水系统数值模型;然后利用矿区水文监测孔的水位数据对模型参数进行校核,获得最终含水层参数、模拟期水均衡项以及流场信息;最后结合区内用水情况、地下水开采现状,设置2号煤实际开采条件下工作面布置与回采方案,利用参数校核后的模型对研究区地下水水位和流场进行情景模拟分析,结果表明:人工隔离层建造位置越靠下,隔水效果越显著。

Aiming at the technical problems of protection and utilization of mine water in the main coal production areas in western China,based on the basic principle of coordinated coal-water mining,a physical simulation experimental platform for coal-water coordinated mining was designed.The experimental platform consists of a material preparation system,a model frame loading system,a water pressure control system,a flexible isolation layer grouting control system and a data acquisition system.Similar materials composed of skeleton structure and cement have been developed.The skeleton structure was used to control the elastic modulus of similar materials,and the cement was used for controlling the overall strength of similar materials.At the same time,mechanical and seepage experiments were carried out on the material,and the experimental results show that the material has good mechanical and seepage characteristics.The No.2 coal’s first mining area of Maiduoshan Coal Mine in the western Ningdong coalfield was taken as the research background,the physical similarity simulation experiment of coal-water coordinated mining was carried out.After the working face was mined for the step distance of 3-5 periodic weighting,through grouting or fracturing treatment on the water-resistant layer,the height evolution characteristics of the water-conducting fissure zone during the coordinated mining of coal and water,the change of water flow at 7 monitoring points,and the roof breaking characteristics were analyzed.The research shows that the location should be outside the perturbation range of the advanced bedrock roof.When the rock layer is fully compacted(after 3-5 periodic weighting),the isolation layer grouting reform process is carried out.The change in seepage flow on different observation lines further confirms the use of fracturing.The process method combined with grouting and plugging isolates the“groundwater”downward seepage channel,which can realize in-situ protection of groundwater.The breaking of the aquifer starts in the fourth cycle with pressure,and the breaking angle is 70°-80°.On this basis,the scenario simulation test was further carried out to simulate the water retention effect of the artificial aquifer under four working conditions.First,the overlying(isolated)aquifer system in the No.2 coal’s first mining area was generalized and established.The conceptual model,mathematical model,and numerical model of the groundwater system were established in the study area.Then the field monitoring hole water level data were used to check and verify the parameters of the model to obtain the aquifer parameters,the water balance item during the simulation period and the flow field information after the parameter check.Combining the water usage in the area and the current status of groundwater mining,a mining plan was set up for the No.2 coal’s working face under actual mining conditions on site,and the parameter-checked model was used to simulate and analyze the groundwater level and flow field in the study area.At the same time,the results show that artificial isolation,the lower the floor is built,and the more significant the water barrier effect.