Study on Interbedded Groundwater Contamination in Mining Areas Coupled with the Failure Process of Grouting Composite

The paper presents the phenomenon of groundwater contamination in the mine area during the failure of the coupled grouting composite. Indoor immersion experiments were conducted on standard grouting composite specimens to understand its failure laws. The experimental results showed that with the increase of the experimental time, the mass of the grouting composite decreased linearly. When the experiment was carried out for 180 days, the mass loss of the grouting composite was 19.834g, and the permeability coefficient gradually increased, which all verified the fact that the grouting composite gradually fails. The main groundwater contamination factors and contamination patterns in the study area were analyzed based on the hydrogeological data of the area. A groundwater contaminant transport model was established for the failure process of the coupled grouting composite, and the contamination potential of the 3222-workface goaf water in the shallow aquifer during the failure of the grouting composite was evaluated. The simulation results of groundwater pollutant transport showed that within 9 years after the grouting engineering was completed, the grouting composite could still maintain a certain degree of impermeability, and no characteristic pollutant ions appeared in the fourth aquifer. When the model ran for 10 years, ferrous ions appeared in the fourth aquifer, but the concentration was only 0.0009 mg/L. After 30 years of model operation, the highest concentration of ferrous ions in the fourth aquifer had reached 0.1609 mg/L. It can be seen that with the passage of time, the strength of the grouting composite in the study area is indeed gradually decreasing. After the strength decreases to a certain extent, it loses its original impermeability and becomes a channel for pollutant transport, with the potential to pollute the shallow aquifer.