Abstract:
It is particularly important to carry out water inrush prediction, especially the accurate prediction of mine water inflow in order to prevent the occurrence of water inrush disaster in the process of coal mining. The analytical method also known as “virtual large diameter well method”,which is widely used in the prediction of mine water inflow, is taken as an example. To overcome the contradiction between the evolution of hydrogeological parameters of mining roof and the dynamic and accurate calculation of mine water inflow, on the basis of further analysis of the authors' previous research, the formation mechanism of water inflow and the evolution law of hydrogeological parameters in the process of mining roof failure are described. The dynamic calculation method of mine water inflow under variable parameters is proposed, and the engineering application and reliability evaluation are carried out. The research shows that firstly, under the influence of roof mining failure, the hydraulic conductivity(K) is characterized by “stable increase-fluctuation change-restoration stability”,and the water table drawdown(S) and influence radius(R) are characterized by “rapid increase-slight decrease-restoration stability”. Secondly, the traditional analytical method has some errors in boundary condition generalization, parameter selection and calculation process when predicting water inflow. Subsequently, a dynamic calculation method of mine water inflow is proposed, which takes into account the “dynamic large diameter well” theoretical model of dynamic change process of goaf area and water table funnel. The first(periodic) caving step is used as the calculation unit to generalize the “dynamic large diameter well” in turn, and the dynamic water inflow during the mining activities is gradually calculated. Finally, taking the No.1306 mining panel of a mine affiliated to Xuzhou Mining Group as an example, the dynamic calculation of mine water inflow under the condition of single parameter change of the reference influence radius(R
0) and double parameter change of the reference influence radius(R
0) and water table drawdown(S) during the mining activities is carried out respectively. The calculation results show that the dynamic calculation method of mine water inflow under the condition of single parameter and double parameter changes can significantly improve the calculation accuracy, and the average relative error is reduced from 140.7% of the traditional analytical method to 88.7% and 10.3% respectively. The research results can lay a certain method foundation for the deduction of interference flow field evolution in the long-term mining process and the dynamic and accurate calculation of mine water inflow in different stages of mining activities, which can better guide the mine water prevention and control and reasonably equip the waterproof and drainage facilities.