Zoning method for mining-induced environmental engineering geological patterns considering the degree of influence of mining activities on phreatic aquifer

Abstract

Environmental engineering geological patterns (EEGPs) are the generalized manifestation of environmental engineering geology with the protection of phreatic water resources as the core, especially in mining areas with fragile eco-geological environment. Based on the formation mechanism of mining-induced EEGPs, with the aim of win-win between protection of phreatic water resources and exploitation of coal resources, this study presents a zoning method for EEGPs. Taking the Yushenfu mining area in northern Shaanxi, China, as a case study, four types of EEGPs (basically unaffected model, gradually restored model after destruction, gradually deteriorated model, and disaster model) were defined separately. On the basis of the degree of influence of mining activities on phreatic aquifer, the zoning method for EEGPs was proposed. Firstly, the height of water-flowing fractured zone (WFFZ) and the residual aquifuge thickness were calculated using multivariate linear regression method. Secondly, according to the relationship among phreatic water leakage, groundwater recharge, and variation in groundwater level, the thickness of laterite, loess and bedrock as the thresholds between the EEGPs were separately determined. Thirdly, based on the thresholds between EEGPs and the linear variation of residual aquifuge thickness combination, the zoning criteria for EEGPs were formulated. Finally, the zoning results were obtained. Furthermore, the verification of the types of EEGPs in coalfaces and the comparison between the zoning results obtained using variable weight theory and those given in the present study indicated that the zoning results presented in the current study are more accurate and reasonable. The research results can provide theoretical basis for solving the contradiction between coal resource exploitation and eco-geological environmental protection.