Risk Assessment of Water Inrush from Aquifers Underlying the Gushuyuan Coal Mine, China

et al. 2021

Geofluids

To further explore the crack evolution of floor rock mass, the mechanism of fault activation, and water inrush, this paper analyzes the crack initiation and propagation mechanism of floor rock mass and obtains the initiation criteria of shear cracks, layered cracks, and vertical tension cracks. With the help of simulation software, the process of fault activation and crack evolution under different fault drop and dip angles was studied. The results show that the sequence of crack presented in the mining rock mass is vertical tension cracks, shear cracks, and layered cracks. The initiation and propagation of the shear cracks at the coal wall promote the fault activation, which tends to be easily caused at a specific inclination angle between 45° and 75°. The fault drop has no obvious impact on the evolution of floor rock cracks and will not induce fault activation. However, the increase of the drop will cause the roof to collapse, reducing the possibility of water inrush disaster. Research shows that measures such as adopting improved mining technology, reducing mining disturbance, increasing coal pillar size, and grouting before mining as reinforcement and artificial forced roof can effectively prevent water inrush disasters caused by deep mining due to fault activation.

Section: Introductionmentioning

confidence: 99%

Analysis of Mining Crack Evolution in Deep Floor Rock Mass with Fault

Chen

et al. 2021

Geofluids

“…North China is rich in coal resources, but coal mining is threatened by underlying confined water due to huge water-bearing karst systems under coal seams [1][2][3]. In particular, with the deep extension of coal mining in North China, the aquiclude between coal seams and karst aquifers becomes progressively thinner, causing more water inrush accidents occurring in the karst aquifer in coal mines [4][5][6]. Therefore, it is of great theoretical and practical significance to evaluate the threat of karst aquifers to coal mining.…”

Section: Introductionmentioning

confidence: 99%

Hydrological Characteristics of Ordovician Karst Top in a Deep Region and Evaluation of Its Threat to Coal Mining: A Case Study for the Weibei Coalfield in Shaanxi Province, China

Cao

et al. 2020

Geofluids

Widely distributed in North China, Ordovician karst is characterized by having high thickness, nonuniform aquosity, and significant water pressure-bearing properties. Deep mining in North China is threatened by associated water hazards; hence, research on the hydrogeological characteristics of deep Ordovician karst is needed. In this study, the Weibei coalfield in Shaanxi Province, China, was selected as the study area, especially mines in the Hancheng and Chenghe mining areas. In situ experiments, including water pumping, water drainage, water injecting and water pressure, and laboratory experiments, were conducted to study the hydrogeological characteristics of the Ordovician karst top in the study area. A comprehensive analysis was conducted on controlling factors for the development of the Ordovician karst top in the study area, and a method for evaluating the water inrush risk in coal mining areas based on karst hydrogeological characteristics was proposed. The research results indicated that the Ordovician karst top in the study area was characterized by heterogeneity, vertical zonation, and partially filled properties, which were mainly controlled by two factors: sedimentation and tectonism. The hydrogeological conditions of the Ordovician karst could be divided into three types: nonfilled and nonsignificant tectonism, filled and nonsignificant tectonism, and significant tectonism. Among them, the filled and nonsignificant tectonism type Ordovician karst top type had a filling thickness of 20 m. Based on karst hydrogeological characteristics, the methods were proposed to evaluate the water inrush risk in the coal mining floor. The practical tests verified the methods.

“…Coal production, however, is constrained by various problems, including water inrushes to the working face during mining (Yuan 2019). Most of China's coal comes from North China type coal fields at present and recently, with increasing mining depth, the threat from the karst fissure water from Carboniferous Taiyuan formation and Ordovician limestone has increased to mining of the lower coal group (Wu et al 2014(Wu et al , 2017. According to incomplete statistics, most major water inrush incidents in China in recent years have been caused by karst fissure water in the coal seam floor penetrating the working face.…”

Section: Introductionmentioning

confidence: 99%

Optimization of group borehole drainage of a mine above a high pressure, low permeability aquifer

Water Practice and Technology

et al. 2020

Abstract Drainage to lower water pressure is an effective measure for preventing and controlling water ingress when mining above a confined aquifer. The deep limestone aquifer in the Huaibei mining area, China, generally has high pressure, low permeability and variable water abundance, so it is difficult to meet single-borehole drainage requirements. In order to achieve good drainage, and take into account engineering and environmental protection requirements, a multi-objective optimization model of group borehole drainage was established. The model takes the minimization of single-hole flow and borehole numbers as the objective functions, and the drawdown in drainage boreholes and the water level control point as the constraint conditions. The particle swarm optimization algorithm was used to solve the model. The results indicate that, for a low permeability aquifer, measures such as using partially penetrating wells, increasing the number of drainage boreholes appropriately and reducing individual borehole yield have good drainage effects. The extent of drilling and amount of drainage are also relatively small. This is all to the good for the drainage. When the optimization results were applied to coal-face drainage in Huaibei the outcome was good.