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

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.