Research Of Coal Ordovician Limestone Water Inrush Prediction Theory And Method

In China coal mine water inrush disaster is serious, especially in North China coalfields. The coal of Carboniferous and Permian is quarrying mainly in North China coalfields. Under the coal seam floor is the Ordovician limestone aquifer which is only a few dozen meters far away from the coal seam floor. Once the Ordovician limestone water occurr accidently, the amount of inrush water is large, the water may submerge mine in a short period of time. It is difficult to hydrophobic drained in a short period of time. The rescue work is difficult to expand. It would cause huge economic loss and personal injury.This article analyses two Ordovician limestone water inrush accidents and the mechanism of Ordovician limestone water inrush. It illustrates the necessity and possibility of the Ordovician limestone water inrush forecasting research. Ordovician limestone water inrush mainly by native hydraulic conductivity structure. Water inrush accident does not occur before seam mining. Only if the coal seam mining face encounter with hydraulic conductivity structure, then the water inrush accident. This paper studies the method of coal mine Ordovician limestone water inrush hazardous area on the basis of Taiyuan University of Technology MTI Ordovician limestone water inrush forecasting methods. And then making the method of coal mine Ordovician limestone water inrush hazardous area used in coal mine Ordovician limestone water inrush monitoring and forecasting system for practical engineering applications.In MTI Ordovician limestone water inrush forecasting methods, the monitoring layer was selected between below the coal seam floor and the small aquifer above Ordovician limestone aquifer, through calculation and analysis of the monitoring layer, Ordovician limestone water inrush forecasting was carried. In this paper, firstly, researched finite element method and finite element program preparation on the seam floor aquifer. The calculation method, selected a certain area of the mining area as the computational domain, splited finite element computational grid to the computational domain finite element mesh, determined the boundary conditions of the computational domain and aquifer parameters, established percolation model of the aquifer, and then calculated the finite element program. The results were water level value of each node in the computational domain of aquifer. Through calculation and analysis of finite element program to monitoring aquifer and the Ordovician limestone aquifer, this study was proposed two division methods of mine Ordovician limestone water inrush danger zone. The one was water inrush danger zone discrimination, according to the calculation error of the calculated water level and the actual level of the monitoring layer; the other one was also water inrush danger zone discrimination, based on the monitoring layer and Ordovician limestone aquifer water level difference. Two kinds of Ordovician limestone water inrush danger zone discrimination are through finite element program calculated water inrush risk index for each node in the computational domain, through different discriminant index divided into different levels water inrush danger zone of the mine Ordovician limestone.Taking Liyazhuang mine and Zhaozhuang mine as examples, The coal mine Ordovician limestone water inrush danger area division method was used in engineering practice. Firstly, according to the mine actual hydrogeological conditions, selecting the computational domain, spliting the computational grid and determining the boundaryconditions, based on the actual hydrogeological conditions of the mine and two mines’ coal seam floor Ordovician limestone aquifer and as monitoring layer of Taiyuan Formation limestone aquifer. Then through simplified percolation model in aquifer of mine carried out the aquifer finite element calculations. Based on the results, drawn the Level contour of Ordovician limestone aquifer in mine zone, and took it as the Level contour of monitoring layer in Taiyuan Formation limestone aquifer and Ordovician limestone water inrush danger zone divided in mine area. Finally, in accordance with the actual situation of the mine, and analyzed and summarized the calculation results.