Study On Groundwater Chemical Characteristics And Water Source Discrimination In Dongtan Mine

It is of great significance for prevention and treatment of mine water hazard to quickly and accurately distinguish the water source of inrush（inrush）accident.In this paper,the groundwater of Dongtan Coal Mine is used as the research object to construct the discriminant model of single mine water source,based on the analysis of constant hydrochemical index content,spatial distribution,hydrochemical type characteristics and main hydrogeochemical effects of main water filled aquifers.In addition,we explore the main sources of mine goaf water by analyzing the water source and passage.The main results are as follows:（1）The contents of HCO₃^-and Na⁺+K⁺in sandstone water,Taiyuan limestone aquifer and goaf water were slightly higher than those in other aquifers,and the contents of Ca²⁺and Mg²⁺in ordovician limestone water are higher than those in other aquifers.The cations in other aquifers except ordovician limestone water are dominated by Na⁺.The main hydrochemistry types of red layer water are HCO₃-Na、SO₄·HCO₃-Na and SO₄-Na,the sandstone water are mainly HCO₃-Na and SO₄-Na,the upper of Taiyuan limestone water is mainly HCO₃-Na,while the lower section has a variety of hydrochemical types.The main hydrochemical types of Ordovician limestone water are SO₄-Ca·Mg and SO₄-Ca.The analysis of ion ratio shows that the dissolution of evaporite（sulfate）is dominant in Ordovician limestone water.The saturation index further shows that gypsum in Ordovician limestone water is in solubilized state while carbonate rock is in a supersaturated state,indicating that gypsum is the main reactive mineral.There are not only the dissolution of evaporite,but also the dissolution of carbonate rock and the weathering of silicate minerals in red bed water,sandstone water and Taiyuan limestone water.（2）Bayes water source discrimination model,objective combined weight-improved set pair analysis model and comprehensive water source discrimination model are constructed respectively for the discrimination of mine single water source.The model test and application results shows that the accuracy of the three models were 62.07%,82.76%and 86.21%respectively.Among them,the comprehensive discriminant model adopts characteristic ion contrast and Bayes discriminant method,which is simple at first and then complex,and determines the water source type step by step.The discriminant effect is the best,which provides a convenient and fast method for mine water source discrimination.（3）Through the analysis of two conditions of sudden（gushing）water source and channel,combine with the data of water diversion fracture zone height,mining floor failure depth and mine stratum structure,it is found that there are three main source modes of mine old empty water:1 Permian sandstone water,2 the Permian and Jurassic red bed sandstone water water,3Permian sandstone water,ash water and the grey water.Combine with water chemical type and comprehensive water source discrimination model,it is found that goaf water mainly derived from sandstone water and red bed water.