scholarly journals Mechanical mechanism of overlying strata breaking and development of fractured zone during close-distance coal seam group mining

2020 ◽  
Vol 30 (2) ◽  
pp. 207-215 ◽  
Author(s):  
Jianguo Ning ◽  
Jun Wang ◽  
Yunliang Tan ◽  
Qiang Xu
Keyword(s):  
Coal Seam ◽  
Fractured Zone ◽  
Close Distance ◽  
Overlying Strata

scholarly journals Height of the Fractured Zone in Coal Mining under Extra-Thick Coal Seam Geological Conditions

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Dequan Sun ◽  
Xiaoyan Li ◽  
Zhijie Zhu ◽  
Yang Li ◽  
Fang Cui
Keyword(s):  
Coal Seam ◽  
Coal Mining ◽  
Process Analysis ◽  
Failure Process ◽  
Analysis Method ◽  
Coal Seams ◽  
Fractured Zone ◽  
Seam Mining ◽  
Borehole Televiewer ◽  
Overlying Strata

The height of the fractured zone caused by coal mining is extremely significant for safely mining under water, water conservation, and gas treatment. At present, the common prediction methods of overburden fractured zone height are only applicable to thin and medium-thick coal seams, not suitable for thick and extra-thick coal seams. In order to determine the overburden fractured zone distribution characteristics of extra-thick seam mining, failure process analysis method of overlying strata was proposed based on key strata theory. This method was applied to 15 m coal seam of Tongxin coal mine, and fractured zone height was determined to be 174 m for 8100 panel. EH4 electromagnetic image system and borehole televiewer survey were also conducted to verify the theory results. The distribution of the electrical conductivity showed that the failure height was 150–170 m. Observation through the borehole televiewer showed that the fractured zone height was 171 m. The results of the two field test methods showed that the fractured zone height was 150–171 m, and it was consistent with the theory calculation results. Therefore, this failure process analysis method of overlying strata can be safely used for other coal mines.

The Seepage Risk Analysis of Surface Runoff Caused by the Shallow Thick Coal Seam Mining

2012 ◽  
Vol 170-173 ◽  
pp. 1353-1358
Author(s):  
Shun Feng Zhang ◽  
Rui Lin Hu ◽  
Xiong Wu
Keyword(s):  
Coal Seam ◽  
Surface Runoff ◽  
Ground Deformation ◽  
Ground Subsidence ◽  
Water Drainage ◽  
Thick Coal Seam ◽  
Mine Area ◽  
Fractured Zone ◽  
Seam Mining ◽  
Overlying Strata

As for shallow thick coal seam, the overlying strata can not form steady structure and will break down until reach the surface ground, which will induced large ground deformation and fractures in the overlying strata during the mining. Under the condition of strong rainfall, surface runoff will influx to the collapse pit or supply to other aquifers, and inrush into the roadway through water flowing fractured zone. This paper takes the 4201、4301、4302、4303 and 4401 coal faces of JingDong mine area in PingShuo for example, predicts the range of ground subsidence、settlement and the height of water flowing fractured zone dynamically after coal face mining, with the Flac3D numerical modeling software. On the base of result above and combined with geomorphic characteristics and hydrologic geology of the mine area, the author analyses risk of surface runoff seepage and put forward a dynamic water drainage design to prevent mine water bursting, which offers scientific foundation and data for safety production of the mine .

A Case Study on Development of Water-flow Fractured Zone During Close-Distance Repeated Coal Mining

2021 ◽  
Author(s):  
Yuanzhong Luan ◽  
Yaofan Shi ◽  
Shui Yu ◽  
Yue Dong ◽  
Yong Yan
Keyword(s):  
Coal Seam ◽  
Coal Mining ◽  
Water Flow ◽  
Water Injection ◽  
Scientific Basis ◽  
Hole Drilling ◽  
Fractured Zone ◽  
Working Face ◽  
Distance Working ◽  
Close Distance

Abstract The upper and lower seam of seam No.3 of some coal mines in Shandong Province are in close proximity which can be regards as close-distance coal seam mining.This paper takes the close-distance working face of Fucun coal mine as engineering background and mainly focuses on the investigation and research on inaccuracy of the forecasting and incompetence of the developing principles of water-flow fractured zone(WFFZ)during close-distance coal seam group mining.First,calculations on the height of WEEZ by adopting empirical formula.And FLAC3D software was established to calculate the height of the overburden WFFZ after repeated mining of the upper and lower seam of seam No.3.At the same time,using the double-ended water plugging observation technology of downhole drilling and upward hole drilling by analyzing the water injection loss ratio of the reference hole and the post-mining hole,the accurate numerical values of the WFFZ and the ratio of WFFZ height to mining height(W-M ratio)are obtained.The comparative analysis shows that the numerical simulation results are close to the measured ones,and the empirical formula is not applicable to the near-distance repeated mining.Finally,the prediction model is established based on the measured height of the WFFZ of multiple working faces,which provides a scientific basis for further exploring the development law of the overlying rock in underwater coal mining and ensuring the safe mining of coal seams at close distances.

scholarly journals Experimental Study on the Fracture Distribution Characteristics of the Overlying Strata in an Abandoned Gob

2021 ◽  
Author(s):  
Chenlin Wang ◽  
Xiaodong Zhang
Keyword(s):  
Coal Seam ◽  
Distribution Characteristics ◽  
Deformation And Failure ◽  
Fractured Zone ◽  
Large Numbers ◽  
Maximum Subsidence ◽  
Caved Zone ◽  
Fracture Distribution ◽  
Overlying Strata ◽  
Vertical Fractures

Abstract A lot of gas resources remain in the abandoned gob. The overlying strata of the abandoned gob are the main places for gas storage and flow. The fracture distribution characteristics of the overlying strata have a significant impact on the gas migration. The mining similarity simulation test device of a plane stress was used to study the deformation and failure characteristics of overlying strata in an abandoned gob. The caved strata of the abandoned gob formed a trapezoidal distribution, and the caving range decreased gradually with an increase in distance from the coal seam. The strata collapsed in the caved zone, whereas the strata collapsed mainly on the bending subsidence in fractured zone. The subsidence curves of caved strata showed a lower concave shape, and the maximum subsidence existed in the middle of the abandoned gob. The caved strata subsidence decreased with an increase in distance from the coal seam. The horizontal fractures were dominant in the fractured zone. The abscission rate of the end mining position was greater than that of the start mining position. Large numbers of vertical fractures existed in the caved zone. The development degree of vertical fractures near the end mining position were larger than that of the start mining position, and the width of the gas-conducting fracture was more than three times that of the start mining position. The development degree, quantity and connectivity of the fracture in the end mining position were better than those in the start mining position.

Research on the Influence by Different Dip Angles Faults of the Damage Height of Superincumbent Stratum

2014 ◽  
Vol 675-677 ◽  
pp. 1421-1424 ◽  
Author(s):  
Zhen Li Fan
Keyword(s):  
Plastic Zone ◽  
Coal Seam ◽  
Small Angle ◽  
High Angle ◽  
Fractured Zone ◽  
Fault Surface ◽  
Influence Area ◽  
Wide Range

For the issue of fault impact on the height of water-flowing fractured zone, the study worked out several damage heights of superincumbent stratum under the influence of different dip angles faults. The research shows that small angle fault influence area is apt to develop a wide range of the plastic zone,and the water-flowing fractured zone of high-angle fault influence area is apt to increase along the fault surface and breakover the aquifers of coal seam roof and floor.

Numerical Analysis on Top Coal Caving of 2# Coal Seam in First Mine of Chagannaoer

2012 ◽  
Vol 594-597 ◽  
pp. 1338-1342
Author(s):  
Qing Hai Li ◽  
Ren Shu Yang ◽  
Wei Ping Shi
Keyword(s):  
Numerical Analysis ◽  
Plastic Zone ◽  
Coal Seam ◽  
Comprehensive Evaluation ◽  
Fuzzy Comprehensive Evaluation ◽  
Mining Technology ◽  
Geological Conditions ◽  
Numerical Software ◽  
Evolution Laws ◽  
Overlying Strata

In first mine of Chagannaoer, 2# coal seam, the mainly mined out layer, was 22.00m thickness in average. In order to meet the requirements of production ability, the mine was planned to apply mining technology of fully mechanized caving. Good or bad of top coal’s caving was an important prerequisite which decided the mining technology of top coal caving could be chosen or not. Due to lack of producing mines in this region and no experience to refer, we simulated the mining process of 2# coal seam using numerical software of FLAC3D, and gained evolution laws of stress and displacement of top coal and overlying strata and expansion laws of plastic zone. Through analysis, we got that the top coal damaged seriously and the top coal could be caved smoothly. Relying on the geological conditions of site, we verified the simulated results with method of fuzzy comprehensive evaluation. Combined with the research results, we decided that 2# coal seam’s caving was better and was convenient for top coal caving, so it was suitable for caving mining in 2# coal seam in first mine of Chagannaoer.

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