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The Chinese government attaches great importance to the ecological restoration of abandoned open-pit mines, increasing the area of cultivated land, and ensuring food security. Soil reconstruction is a crucial step in ecological restoration of abandoned open-pit mines. This study investigated the utilization of hydrophobic sand to create an Air-Permeable Aquiclude (APAC) under the plant root zones, thereby minimizing water infiltration and enhancing soil aeration. Field plot experiments for 2 years have been conducted, with control groups, Clay Aquitard (CAT), and Plastic Aquiclude (PAC), to evaluate the effects of APAC on rice yield, nitrogen utilization, and water efficiency. The findings revealed that utilizing APAC resulted in a significant rise in rice yield, ranging from 8.09 t/hm² to 9.27 t/hm², which were 7.67–27.16% higher than the control groups. Moreover, the APAC led to a remarkable reduction in irrigation water usage by 37.08%, alongside a substantial boost in Irrigation Water Productivity (IWP) efficiency by 28.64–71.12%. Notably, Nitrogen Partial Factor Productivity (NPFP) exhibited a substantial increase of 7.69–27.06%. These outcomes underscore the APAC’s positive role in water and nutrient conservation and enhanced yields.

Solid backfill coal mining technology can be safely and efficiently used to exploit coal resources under aquifers, without causing harm to the water resources and the environment. Nevertheless, the mechanism of fracture development and seepage channel or pathway control in the key aquiclude strata (KAS) in backfill coal mining under fluid–solid coupling have not been studied. Based on the similarity theory of fluid–solid coupling physical simulation, this study involves experimental evaluation of similar materials and characteristics of composite KAS, backfill body, and aquifer. Subsequently, we designed and employed three experimental models for physical simulation, corresponding to backfill materials’ compaction ratios (BMCRs) of 0%, 65%, and 80% using the geological conditions of mining face No. 101 under the aquifer in the Wugou coal mine. Fracture evolution laws, mining-induced deformation, and stress distribution characteristics of composite KAS with different BMCRs are studied. The backfill body can effectively weaken the influence of mining stress, such as the maximum subsidence, sinking speed, initial or periodic fracture damage area of the composite KAS, inhibiting the formation of seepage cracks and water inrush channels. The increase in the BMCR plays an important role in the closure and repair of developed fractures.

When mining deep coal seams with thin bedrock and thick alluvium, the collapse and fracture of thin bedrock layers may cause geological disasters, such as water inrush and sand inrush of the mining face. Comprehensively obtaining the response data of coal mining and reasonably analyzing the failure characteristics of overlying strata are helpful in guiding safe production. In this study, the caving zone heights of overlying strata are obtained by field detection during layered mining. Then, the caving zone heights during the once-full-height mining are evaluated by theoretical analysis. Further, the force and failure characteristics of coal–rock structures under different mining conditions are compared by the simulation detection and analysis. Finally, the results of on-site observation, theoretical analysis, and simulation detection are compared and discussed, and an optimized mining technology is proposed to ensure safe mining. The research shows the caving zone heights of on-site and simulation detections are, respectively, 14.65 m and 13.5 m during bottom-layer mining, which is larger than the caving zone heights of the top-layer coal mining. During once-full-height mining, the maximum caving zone height of simulation detection is 21 m, which is in between two standard results. For the mechanical responses of an aquiclude clay layer under thick loose alluvium, the maximum disturbance displacement of clay aquiclude is 5.8 m during layered mining, which is slightly larger than the disturbance displacement of once full-height mining; however, the maximum stress of the clay layer is 25 MPa during once-full-height mining, which is larger than the maximum stress of clay layer during layered mining. For the clay aquiclude failure, the clay layer during layered mining is in the deflection deformation area, and there is no obvious fracture structure to inrush the water and sand of thick loose alluvium; however, the clay layer during once-full-height mining is prone to produce obvious fracture structure. Therefore, the layered mining technology can effectively reduce and prevent the water/sand inrush disaster of mining working face.

Water inrush from confined aquifers in coal seam floor poses a great threat to the safety production of coal mines, while the aquiclude in coal seam floor is a key factor to avoid water inrush disasters. Therefore, an objective and accurate evaluation on the water-resisting ability of the aquiclude can effectively identify potential risk areas of water inrush and plays an important role in preventing such disasters. In this study, Longfeng coal mine was taken as an example. And based on the availability of data and the representativeness of factors, thickness of effective aquiclude, brittle rock thickness of aquiclude, rock quality designation of aquiclude, consumption of drilling fluid, mudstone ratio of aquiclude and fault fracture zone were selected as evaluation factors for water-resisting ability. Besides, the non-linear mathematical method—entropy weight method was combined to construct a comprehensive evaluation model of the water-resisting ability of aquiclude in coal seam floor. On this basis, the information processing and spatial display functions of GIS technology were used to make a thematic map of influencing factors and the thematic map was compositely superimposed. Finally, the evaluation on the water-resisting ability of aquiclude in coal seam floor in Longfeng coal mine was realized. The multi-source information fusion evaluation method based on GIS and entropy weight can comprehensively and objectively reflect the feature that the water-resisting ability of aquiclude in coal seam floor was controlled by multiple factors and had complex formation mechanisms. Also, the evaluation results were displayed intuitively and visually and can provide a scientific basis for the prevention and control of water inrush disasters from coal seam floor.

Aims To achieve ecological restoration of urban water pollution, this study uses vegetation filter strips to filter and remove pollution caused by aquiclude in vegetation restoration technology. Methods This study focuses on the main pollution factors of urban water pollution, nitrogen and phosphorus, and conducts comparative experiments on different vegetation filter belts to analyze their removal effects on pollution factors. Results With the decrease of runoff intensity, the removal rates of TSS and TP significantly increased by 22.97% and 20.04%, respectively. At different pollution concentrations, the removal effect of the experimental group exceeded that of the control group. The removal rate also improved with the added pollution concentration. The removal efficiency of experimental group 3, which used Adiantum capillus-veneris as the remediation zone, was the highest. The maximum removal rates in TP, NH 4 + -N, TN, NO 3 − -N and TSS pollution factors reached 88.34%, 85.35%, 85.04%, 84.92%, and 87.21%, respectively. Conclusions The application of vegetation restoration technology in the ecological restoration of urban water pollution has confirmed its important role and practical significance in controlling urban water pollutants, providing theoretical basis and practical reference for the ecological restoration of urban water pollution.

As coal mining is extended to ever-greater depths, the factors affecting the safe mining of coal seams are becoming increasingly complicated. High-pressure confined water in the coal seam floor can pose a major threat to the safety of coal mining. Therefore, based on the analysis of various factors that affect water inrush from coal seam floors, this study develops a geological engineering model of high-pressure confined water damage assessment for coal mine face floors. The model adopts six evaluation factors: coal mining depth, coal seam thickness, thickness of the aquiclude, hydrostatic pressure, brittle-rock thickness, and the distribution of faults and folds. The comprehensive weight of the six factors is obtained through analytic hierarchy processing (AHP) and the entropy weight method (EWM) to establish an AHP–EW risk index model (AEM). AEM is applied for the evaluation of two coalfaces in a study area in North China, and the water inrush risk zonation of the coalface floors is determined. Finally, the results given with AEM are compared with those from the traditional water inrush coefficient method, and its applicability in other mining areas is also validated. The results show that the proposed model provides more accurate evaluation results than the traditional method and that its application is more practical.

Hydraulic fracturing is widely applied for unconventional energy to improve production capacity. But concerns exist about the potential negative impacts of hydraulic fracturing on the environment. Previous researches evaluated the impact of hydraulic fracturing on the environment by water quality monitoring qualitatively. Some numerical models were estimated to study it quantitatively. But there is uncertainty in the acquisition of mechanical parameters of deep rock. This study presents a statistical model for studying the environmental impact of hydraulic fracturing on the groundwater in the region. The contribution ratio of CBM co-produced water is calculated to estimate the containment degree by End Member Mixing Analysis. In order to obtain the end members purely, Vertex Component Analysis and Principal Components Analysis are used to extract the end members. The model is applied to Qinshui Basin, China. It was shown that hydraulic fracturing doesn’t damage the aquiclude in the region. But shallow groundwater was polluted by CBM co-produced water in the Shizhuang Block. The mixing path of CBM co-produced water is from the surface to the aquifer.

The effective discrimination of aquiclude mining stability is one of the important indexes for the feasibility judgement of water-conserved mining. Based on the mining-induced deformation characteristics of weakly cemented aquiclude and the water level change of weakly cemented aquifer in northwest China, a mechanical model of mining stability of weakly cemented aquiclude is established, and the mining instability criterion of weakly cemented aquiclude and its influencing factors are analyzed. The results show that the weakly cemented aquiclude has strong plastic deformation ability and mainly undergoes bending deformation during coal mining. Considering the mining-induced bending deformation of weakly cemented aquiclude and the groundwater pressure variation of the weakly cemented aquifer, the expressions of the deflection, stress components, and strain components of weakly cemented aquiclude are derived. Furthermore, the stress instability and strain instability criteria of the weakly cemented aquiclude are proposed. The influences of aquiclude thickness, elastic modulus, Poisson’s ratio, groundwater level, coalface length, and longwall panel length on the mining stability of weakly cemented aquiclude are analyzed. The research results are applied to the feasibility judgment of water-conserved mining in Xinjiang Ehuobulake Coal Mine, and the validity of the mining stability criterion of weakly cemented aquiclude is verified.

Aquiclude plays a critical role in the occurrence of mining-induced roof water inrush in underground coal mines. This paper proposes an assessment index for the evaluation of aquiclude stability and a threshold value of water inrush from the roof, based on a case study of roof water inrush accidents in Cuimu coal mine, China. The relation between roof water inrush and water level variation in the aquifer, and the characteristics of aquiclude deformation, were studied in this assessment. Using the developed assessment criteria, the likelihood of roof water inrush was categorized into different risk levels, which were followed by a proposal for roof water inrush control measures. The main findings of this study are: a) in Cuimu coal mine, the waterbody in the bed separation between the upper aquifer and the aquiclude directly causes the inrush, and inrush occurs after the water level declines in the aquifer; b) tension-induced horizontal strains of aquiclude can be regarded as the index to evaluate the stability of aquiclude affected by underground coal mining—roof water inrush occurs when the maximum horizontal strain reaches a threshold of 10mm/m—c) based on the critical mining height for aquiclude instability, and the different thicknesses of barrier layers, high-risk zones are identified and inrush controls are proposed.

Water supply in the Abakaliki Area of Southeastern Nigeria and its environs has been a source of worry. The area is marked by a series of abortive boreholes, sparsely productive boreholes, and failed water wells. These problems are a result of the direct and indirect function(s) of the prevailing geology of the area which is underlain by aquiclude (Abakaliki Shale, lenses of siltstone and sandstone) dominantly indurated shale. Sixteen (16) vertical electric sounding (VES) were acquired using a resistivity meter. The acquired data was plotted on a bi-log graph using INTERPEX and SURFER. Quantitative and qualitative interpretations were used in preparing geoelectric layers and layer parameter maps. Three (3) to five (5) geoelectric layers were delineated. The first layer is a compacted lateritic overburden. VES 1, 3, 4, 6, 11, and 15 were observed to have thin layers of clay with very low apparent resistivity values with an average of 2.642 Ωm and average thickness of 1.08 m, and depth generally less than 10 m. Fractured and non-fractured/baked shale layers were dominant in all points of the study area. The non-fractured consolidated shale has a high apparent resistivity value ranging from 180.3 Ωm to 770.42 Ωm with an average of about 339.53 Ωm while the fractured shale has an average resistivity value of about 21.36–68.79 Ωm and an average of 38 Ωm. The confinement of the aquifer implies that the indurated shale generally underly the Abakaliki Area. The low resistivity value of the fractured shale is an indication of the presence of fluid, possibly water. The results of this research implied that the application of exploration method(s) that could delineate the subsurface fractures should precede groundwater development in the area. Also, there is no specific depth to the water table in the area; however, the area has a generally shallow depth to groundwater on average.