scholarly journals Analysis of the Karst Development Law Based on Multiple Exploration Technologies of Cambrian Limestone

2020 ◽  
Author(s):  
J.W. Guo ◽  
B. Zhang ◽  
X. Y. Wang
Keyword(s):  
Shallow Water ◽  
Coal Mine ◽  
Water Inrush ◽  
Tracer Test ◽  
Karst Water ◽  
The West ◽  
Hydraulic Connection ◽  
Karst Development ◽  
Detection Techniques ◽  
Closed Area

Abstract Coal mine floor limestone aquifers are a major source of water inrush from the coal seam floor and a serious threat to the safety of coal mining. In order to reduce and avoid the occurrence of water inrush within the coal mine, we use multiple detection techniques, which are geophysical exploration technology , drilling technology, water inrush accidents and tracer test, to develop a multi-faceted exploration of karst development and analyze its development characteristics in the Chaochuan mine No. 1 well of Pingdingshan Coal Co.Ltd, Henan Province, China. The results show that, the Cambrian limestone (CL) karst water is poor; there is a certain hydraulic connection. Near faults F5, F1, and SF28, the area is less water-rich area, the water is weak, and the deep karst water forms a closed area; 61.54 % of shallow water inrush accidents in the Taiyuan limestone and CL karsts were caused by large tectonic and nearby shallow faults. The karst vertical zonation is shallow; the shallow water level decreased more in the West Wing of the No. 1 well than in the East Wing at elevations above 140 m and below -150 m. The F125 level decline is greater than that of the east, and the west fault is more than 170 m due to the hydraulic connection intrusive barrier wings of the karst water. the East Wing below -150 m F125 fault was weak and uneven on both sides of the hydraulic connection.

scholarly journals Karst Water Pressure’s Varying Rule and Its Response to Overlying Strata Movement in Coal Mine

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Jian Hao ◽  
Hua Bian ◽  
Anfa Chen ◽  
Jiahui Lin ◽  
Dongjing Xu
Keyword(s):  
Water Level ◽  
Water Column ◽  
Coal Mine ◽  
Simulation Experiment ◽  
Water Pressure ◽  
Water Inrush ◽  
Column Height ◽  
Karst Water ◽  
Working Face ◽  
Water Column Height

Karst water is widespread throughout China and is heavily influenced by complex geological conditions, and floor inrush of karst waters associated with coal seams is the second most common coal mine disaster in China. Due to the limitation of precision and cost of geophysical exploration technology, the volume and pressure of karst water are challenging to measure, especially during the mining process. Therefore, predicting karst pressure’s response to mining is critical for determining the mechanism of water inrush. Here, closed karst water pressure (CKWP) response to mining was studied in an innovative physical simulation experiment. In the simulation experiment, a capsule and a pipe were designed to reflect CKWP and the water level. In the experiment, the vertical stress and karst water level were monitored throughout the process of an advancing coal panel. Monitoring results show that the range of the abutment pressure was about 40 cm, and the peak coefficient value was about 2. When the working face is far away from the water capsule, the stress and water column near the water capsule have no obvious change. With the working face 10 cm from the water capsule, the stress and water column height increased significantly. When the working face was right above the water capsule, the stress and water column rose sharply and reached the maximum value. When the working face advanced beyond the water capsule, the stress and water column height declined. Through establishing a structural mechanics model, the karst water system underneath the working face is assumed to be a hydraulic press. Accordingly, the compressed area was assumed to be a piston. The karst water pressure increases sharply, while the piston is compressed, increasing water inrush risk. This discovery may help determine the water inrush mechanism from a novel point of view.

scholarly journals Identification of Hydraulic Connection Points between Different Confined Aquifers in the Liyazhuang Coal Mine

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Zhenghe Liu ◽  
Peiyun Zhao ◽  
Lusheng Yang ◽  
Jingui Zhao ◽  
Hailong Ye ◽  
...  
Keyword(s):  
Flow Field ◽  
Coal Seam ◽  
Numerical Simulations ◽  
Water Level ◽  
Coal Mine ◽  
Prevention And Control ◽  
Water Inrush ◽  
Hydraulic Connection ◽  
Contact Points ◽  
And Control

Water inrush from coal seam floors is one major geological obstacle hindering safe and efficient production activities in mines. Determining the source of water inrush can facilitate its prediction and guide decisions regarding measures for prevention and control. The process of identifying the location of hidden hydraulic contact points in different confined aquifers forms the basis of hydrogeological explorations. It is also the basis for categorizing mine areas prone to water inrush and making qualitative decisions regarding the prevention and control of water inrush. In this study, the positions of hidden hydraulic contact points between the Ordovician Fengfeng and Shangmajiagou formations in the basement of the Liyazhuang coal mine were determined using numerical simulations of the flow fields. First, each node of the finite element grid was considered as a water inrush point to determine the water level at other nodes. Subsequently, the error between measured and simulated water levels, determined based on the flow fields, was determined using the least squares method. The node with the minimum error was then considered as the hidden hydraulic contact point. The simulation results for the flow field indicate a distance of 5000 m between the hydraulic connection and the water inrush points located between the peak formation and the Majiagou aquifer in the Liyazhuang coal mine. Furthermore, the hydraulic relationship between them is poor. Observational data of water inrush from the floor of the No. 2 coal seam and the water level of the confined aquifer in the Liyazhuang coal mine, including the water quality test data of different Ordovician ash aquifers, show that the source of water inrush from the floor of the No. 2 coal seam is the aquifer of the Fengfeng Formation. This finding is consistent with the results of the numerical simulations of the flow field. The results demonstrate that, in mining areas subjected to high pressures, numerical simulations of the flow field can serve as an effective tool for determining the location of hidden hydraulic contact points.

scholarly journals Groundwater-Mixing Mechanism in a Multiaquifer System Based on Isotopic Tracing Theory: A Case Study in a Coal Mine District, China

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Pinghua Huang ◽  
Xinyi Wang
Keyword(s):  
Coal Mine ◽  
Water Inrush ◽  
Environmental Isotopes ◽  
Groundwater Sample ◽  
Karst Water ◽  
Biological Degradation ◽  
Sample Number ◽  
Organic Matters ◽  
Sandstone Aquifer ◽  
Groundwater Mixing

Water inrush of mixed groundwater is the primary threat against safe production in coal mines. To study the mixing mechanism of a multiaquifer groundwater system, groundwater samples were collected from different strata in a typical North China-type coalfield (Chaochuan Coal Mine) and were then tested using environmental isotopes (18O, 2H, 3H, 13C, and 14C) and hydrochemical ions (Ca2+, Mg2+, Na+, K+, HCO3−, SO42−, and Cl−) as tracer agents. Results demonstrate that HCO3− and Cl− exhibit a linear relationship with the mixing ratio, whereas Na+, Ca2+, and SO42− show certain degrees of curvature. This condition indicates that groundwater mixing involves major chemical actions. The δD–δ18O plot reveals that karst water and groundwater from Quaternary and sandstone aquifers are mainly mixtures of local rainfall, evaporated groundwater, and “palaeo-groundwater.” The 3H < 0.5 TU and 14C content in the groundwater sample number 27 is 13.6 pmc, which suggests that this groundwater sample is the last rainfall recharge in the ice stage. Palaeo-groundwater in a sandstone aquifer accounts for more than 60%, and that in the Cambrian limestone aquifer is lower than 20%. Groundwater from the Quaternary aquifer is supplied by “modern” rainfall. The δ13C of groundwater from a sandstone aquifer decreases with the increase in CO32− + HCO3−, and this condition reflects that organic matters exhibit biological degradation reaction. However, δ13C increases with the rise in CO32− + HCO3− in the Cambrian limestone groundwater, and this condition indicates that organic matters produce methane due to methanogens.

Application of Kriging Method to Evaluation of the Water Inrush Risk

2013 ◽  
Vol 807-809 ◽  
pp. 2294-2298
Author(s):  
Guang Peng Zhang ◽  
Wen Quan Zhang ◽  
Pei Cong Sun ◽  
Kai Zhao ◽  
Zhi Da Liu
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Interpolation Method ◽  
Water Inrush ◽  
Mining Area ◽  
Difficult Problem ◽  
Kriging Interpolation ◽  
Karst Water ◽  
Kriging Interpolation Method ◽  
Floor Water Inrush

The water disaster of floor in coal mine is a difficult problem of production and scientific research. Coal mine workers and scientific-technological workers are very concerned about this problem.The pressure-bearing karst water of 5# limestone poses a threat to production of 8# coal seam. Combining with the method of water inrush coefficient and Kriging interpolation method analyze the possibility of water inrush. The water inrush coefficient contour map has good convexity, verisimilitude and smoothness. Results accord with actual situation and intuitively reflect the 8# coal seam floor water inrush risk .The water inrush coefficient in the actual mining area is not more than 0.1 MPa/m, but in the future and in mining regional the water inrush coefficient could be very big, so we need to take the necessary precautions.

Is predation intensity reduced with increasing depth? Evidence from the west Atlantic stalked crinoidEndoxocrinus parrae(Gervais) and implications for the Mesozoic marine revolution

Paleobiology ◽  
1996 ◽  
Vol 22 (3) ◽  
pp. 339-351 ◽  
Author(s):  
Tatsuo Oji
Keyword(s):  
Shallow Water ◽  
The Other ◽  
The West ◽  
Bathymetric Range ◽  
Late Mesozoic ◽  
Predation Intensity ◽  
Stalked Crinoids ◽  
The Caribbean ◽  
Mesozoic Marine Revolution ◽  
Sublethal Predation

The number of regenerated arms was counted on specimens of two distinct phenotypes of the stalked crinoidEndoxocrinus parrae(Gervais) from a wide bathymetric range in the Caribbean (178-723 m). In one phenotype, the sample was divided into two groups, one from shallower (< 500 m) depths, the other from deeper (≥ 500 m); in the other phenotype the group divided at 550 m. In both phenotypes, the frequency of regenerated arms is significantly higher in specimens from shallower water than in those from deeper water. If the regenerated arms inEndoxocrinus parraewere the result of sublethal predation, as previously suggested, then predation intensity is higher in shallow water than deep water. These results are consistent with the idea of the late Mesozoic marine revolution—that there has been stronger predation on various invertebrates in shallow-water environments since the late Mesozoic. The stalked crinoids may have been unable to cope with increased predation in shelf environments, and they migrated to offshore environments.

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