Mechanism of water rock interaction in coal measure sandstone aquifer disturbed by grouting engineering: A case study of Taoyuan Coal Mine

Coal measure sandstone fissure water is one of the important water filling sources in coal mine. This paper takes the Permian coal measures in Taoyuan Coal Mine of Huaibei Coalfield as the research object. Based on the analysis of the water chemical characteristics of coal measures since the grouting treatment of water disaster in the mine, the mechanism of hydrogeochemical action of groundwater and its controlling factors were expounded. The results show that during the grouting treatment project, the main cation in coal measures water was Na⁺, and the main anion was SO₄^2-; the relationship of cation mass concentration was Na⁺ > Ca²⁺ > Mg²⁺, and the correlation of anion mass concentration was SO₄^2- > HCO₃^- > Cl^-. Through the analysis of Durov hydrochemical diagram, the main hydrochemical types of coal measures during grouting treatment were Na-SO₄ and Na-HCO₃. There were oxidation of pyrite or dissolution of carbonate and sulfate in coal measures water, accompanied by a certain degree of cation alternate adsorption and desulfurization, especially during the implementation of grouting treatment project, the cation alternating adsorption was enhanced. Large scale water inrush, water prevention and control engineering by grouting, geological structure background and mining activities all affected the water-rock interaction of coal measures water in varying degrees, and the influence degree increased with the increase of grouting treatment scope.