A Study of Interbedded Groundwater Contamination in a Mining Area and the Process of Grouting Composite Failure

Grouting is extensively used in mining areas susceptible to potential water hazards. However, as time elapses, grout composites can fail, thereby jeopardizing the subsurface aquifer system and giving rise to groundwater contamination. This study involved the production of standardized grout composite specimens, followed by laboratory immersion testing. After a 180 days of immersion, the mass of the grout composite was reduced by 19.83 g, constituting a 0.86% reduction from its initial weight, accompanied by a gradual increase in the permeability coefficient. By integrating the experimental outcomes, a groundwater pollutant transport model was developed to elucidate the effect of this failure process. According to the model results, no distinctive pollutant ions would be detected in other aquifers within a decade following grouting completion as the grout composite retained its strength during this period. After 30 years, the highest concentration of ferrous ions in the target aquifer reached 0.16 mg/L, which though low, suggests that failed grout composites can serve as conduits for pollutant transport, and thereby adversely affect the water quality of other aquifers.