A Case Study of Surface Borehole Wall Dislocation Induced by Top-Coal Longwall Mining

Ju, Jinfeng; Xu, Jialin; Xu, Jizhao

doi:10.3390/en10122100

Cited by 6 publications

(3 citation statements)

References 14 publications

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“…The subsidence produced by the ground movement is different to the horizontal movement [38,39], so the deformation is characterized by slope, curvature, and horizontal strain. The deformation of the aquitard floor at different mining depths after coal mining ended is shown in Figure 10 It was shown that the subsidence, the slope, the horizontal strain, and the curvature of the clay aquitard floor enlarged as the thickness of the overlying strata decreased.…”

Section: Relationship Between the Deformation Of The Floor Aquitard Amentioning

confidence: 99%

Physical Simulation of Strata Failure and Its Impact on Overlying Unconsolidated Aquifer at Various Mining Depths

Zhang

Shi

et al. 2018

Water

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Underground mining severely lowers the water table and worsens the ecological environment. To determine the mechanism influencing drawdown in unconsolidated aquifers induced by deep mining combined with overburden movement, with a view to environmental protection, physical simulations for three different depths were designed to investigate and contrast deformation and fracture distribution characteristics at diverse depths after mining. The impacts on overlying unconsolidated aquifers were then analyzed by monitoring overburden movement and ground water level data, and the deformation limit was estimated. Modeling results indicated that coal mining had different impacts on the overlying unconsolidated aquifer via various mechanisms of groundwater level reduction. The aquifer outside the fractured water-conducting zone could be affected by coal mining, and the water tables dropped rapidly. The failure and the deformation features of the aquitard floor were the key to revealing the mechanism of groundwater depletion in deep mining. The effects on aquitard decreased as the distance from the working face increased. A relationship between the strata deformation and the drawdown rate was established; that is, the rate of decline of the groundwater level did not accelerate until the maximum subsidence of the aquitard floor exceeded approximately 0.9 m, or the subsidence-bending area of the aquitard floor exceeded approximately 156 m 2 .

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Section: Relationship Between the Deformation Of The Floor Aquitard Amentioning

confidence: 99%

Physical Simulation of Strata Failure and Its Impact on Overlying Unconsolidated Aquifer at Various Mining Depths

Zhang

Shi

et al. 2018

Water

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“…The observation hole was 230 m from the central transport roadway for 2# seam and 95 m from 20104 tailgate, as shown in Figure 1. This hole is about 250 m deep and its mouth at the surface has an elevation of +829.9 m. The positions of key strata in the overburden were identified using KSPB, software for locating key strata (the computational method of this software is based on the key Strata theory and the identification of KS) [25,26]. It was found that there are four key strata above working face 20104, including a PKS and three secondary key strata (SKS) (Figure 3).…”

Section: Field Measurements Of the Height Of Cfzmentioning

confidence: 99%

Influence of Spatial Relationships between Key Strata on the Height of Mining-Induced Fracture Zone: A Case Study of Thick Coal Seam Mining

Wang

Cao

et al. 2018

Energies

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Abstract:The behavior of the overburden of working face 20104 at the Wangjialing coal mine was investigated using borehole imaging. The measured height of the conductive fracture zone (CFZ) in the overburden, 148 m, is significantly different from the height that is predicted by an empirical formula. The spatial relationships between key strata (KS) required for their fracturing and their influence on the CFZ's height were analyzed. The results demonstrate that the spatial relationships between adjacent KS are a major factor behind the abnormal increase in the height of CFZ relative to the coal seam. The height of linkage (HoL) between KS was introduced and an equation for calculating this height was proposed. The study found that the fracturing of a KS could induce fracturing of the adjacent KS above it if their height difference was smaller than the HoL between them. Otherwise, the fractures resulting from the lower KS would terminate at the bottom of the higher KS. When the location of a high KS satisfies certain requirement, the spatial linkage between adjacent KS will allow for the conductive fractures arising in a lower KS to propagate through the high KS as well as the strata controlled by it, thus increasing the height of CFZ in overburden.

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“…Wen et al [14] found that the key stratum has a significant impact on the behavior of the strata in a stope by theoretical calculation, and divided it into a "single key stratum" structure and a "double key strata" structure. Ju et al [15] adopted in-situ investigation of surface boreholes and found a strong correlation between dislocation inside the boreholes and the location of the key strata, from which the fracture and movement of the key strata with the advancing process of the working face was inverted. Kuang et al [16] carried out an in-situ investigation to determine the law of fracture and movement of a key stratum.…”

Section: Introductionmentioning

confidence: 99%

Key Strata Identification of Overburden Based on Magnetotelluric Detection: A Case Study

et al. 2020

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The severe overburden failure induced by high-intensity mining is the essence of eco-environmental problems in Northwest China, and the degree of overburden failure is closely related to the location and failure of key strata (KS), which controls part of the strata in the overburden. In order to solve the problems of traditional KS based on mechanical parameters and numerical simulation methods that are time consuming, complex, expensive, and work intensive, it is necessary to find a simple and fast KS identification method. Based on the KS theory, which has been successfully applied in the field practice for nearly 30 years, and its current identification method by calculation or software, the magnetotelluric (MT) detection method was selected. According to the principle of MT detection method, the main influencing factors were analyzed. By summing up the relationship between the geological characteristics of the KS and its apparent resistivity (AR), the AR trends of ten kinds of lithology are given, and the identification mechanism of the MT detection method is revealed. Through the field measurement in Daliuta coalmine and the accuracy verification by the theory calculation, the KS obtained by the two methods are consistent. The results show that the MT detection method can be used to quickly identify the KS, and it is simple, convenient, and fast. It provides a reference for optimizing mining technology, mine pressure control, and mine precision.

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A Case Study of Surface Borehole Wall Dislocation Induced by Top-Coal Longwall Mining

Cited by 6 publications

References 14 publications

Physical Simulation of Strata Failure and Its Impact on Overlying Unconsolidated Aquifer at Various Mining Depths

Physical Simulation of Strata Failure and Its Impact on Overlying Unconsolidated Aquifer at Various Mining Depths

Influence of Spatial Relationships between Key Strata on the Height of Mining-Induced Fracture Zone: A Case Study of Thick Coal Seam Mining

Key Strata Identification of Overburden Based on Magnetotelluric Detection: A Case Study

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