scholarly journals Evolution Mechanism of Water-Conducting Channel of Collapse Column in Karst Mining Area of Southwest China

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Zhengzheng Cao ◽  
Yulou Ren ◽  
Qinting Wang ◽  
Banghua Yao ◽  
Xinchao Zhang
Keyword(s):  
Coal Seam ◽  
Southwest China ◽  
Water Inrush ◽  
Mining Area ◽  
Karst Collapse ◽  
Coal Field ◽  
Conducting Channel ◽  
Evolution Mechanism ◽  
Working Face ◽  
Collapse Column

There are many karst collapse columns in coal seam roof in the southern coal field in China, which are different from those in coal seam floor in the northern coal field, due to the stratum characteristics. The karst collapse column in coal seam roof tends to reactivate and conduct water and induce the serious water inrush disaster, when the karst collapse column communicates with the overlying aquifer. In order to reveal the evolution mechanism of water-conducting channel of collapse column in karst mining area of southwest China, the aquifers and water inflow rule in 1908 working face in Qianjin coal mine are analyzed. Besides, the particle size distribution and mineral component of collapse column are researched by the X-ray diffraction test and the screening method, which are the basis for researching the water inrush mechanism in karst collapse column. On this basis, the water inrush of roof collapse column under the influence of mining is researched by establishing the numerical calculation model with the UDEC numerical software. The results show that the water flowing into the 1908 working face comes from the Changxing formation aquifer and Yulongshan formation aquifer above the coal seam, and the proportion of coarse particles and fine particles in collapse column is 89.86% and 10.14%, respectively. With the advance of working face, the water-conducting channel connected the working face with the aquifer, or the surface is formed by collapse pits, karst caves, and collapse column. The research results can be treated as an important basis for the water-preserved mining in southern coal field in China.

scholarly journals A Mechanical Model of the Overlying Rock Masses in Undersea Coal Mining and a Stress-Seepage Coupling Numerical Simulation

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Jie Fang ◽  
Lei Tian ◽  
Yanyan Cai ◽  
Zhiguo Cao ◽  
Jinhao Wen ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Coal Mining ◽  
Water Inrush ◽  
Mining Area ◽  
Analysis Model ◽  
Fractured Zones ◽  
Working Face ◽  
Seam Mining ◽  
Overlying Strata

The water inrush of a working face is the main hidden danger to the safe mining of underwater coal seams. It is known that the development of water-flowing fractured zones in overlying strata is the basic path which causes water inrushes in working faces. In the engineering background of the underwater mining in the Longkou Mining Area, the analysis model and judgment method of crack propagation were created on the basis of the Mohr–Coulomb criterion. Fish language was used to couple the extension model into the FLAC3d software, in order to simulate the mining process of the underwater coal seam, as well as to analyze the initiation evolutionary characteristics and seepage laws of the fractured zones in the overlying strata during the advancing processes of the working face. The results showed that, during the coal seam mining process, the mining fractured zones which had been caused by the compression-shear and tension-shear were mainly concentrated in the overlying strata of the working face. Also, the open-off cut and mining working face were the key sections of the water inrush in the rock mass. The condition of the water disaster was the formation of a water inrush channel. The possible water inrush channels in underwater coal mining are mainly composed of water-flowing fractured zones which are formed during the excavation processes. The numerical simulation results were validated through the practical engineering of field observations on the height of water-flowing fractured zone, which displayed a favorable adaptability.

scholarly journals Modeling Rock Fracture Propagation and Water Inrush Mechanisms in Underground Coal Mine

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Shichuan Zhang ◽  
Baotang Shen ◽  
Yangyang Li ◽  
Shengfan Zhou
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Rock Fracture ◽  
Water Inrush ◽  
Water Channel ◽  
Karst Collapse ◽  
Mining Equipment ◽  
Geological Conditions ◽  
Fracturing Process ◽  
Collapse Column

Water inrush in underground mines is a major safety threat for mining personnel, and it can also cause major damage to mining equipment and result in severe production losses. Water inrush can be attributed to the coalescence of rock fractures and the formation of water channel in rock mass due to the interaction of fractures, hydraulic flow, and stress field. Hence, predicting the fracturing process is the key for investigating the water inrush mechanisms for safe mining. A new coupling method is designed in FRACOD to investigate the mechanisms of water inrush disaster (known as “Luotuoshan accident”) which occurred in China in 2010 in which 32 people died. In order to investigate the evolution processes and mechanisms of water inrush accident in Luotuoshan coal mine, this study applies the recently developed fracture-hydraulic (F-H) flow coupling function to FRACOD and focuses on the rock fracturing processes in a karst collapse column which is a geologically altered zone linking several rock strata vertically formed by the long-term dissolution of the flowing groundwater. The numerical simulation of water inrush is conducted based on the actual geological conditions of Luotuoshan mining area, and various materials with actual geological characteristics were used to simulate the rocks surrounding the coal seam. The influences of several key factors, such as in situ stresses, fractures on the formation, and development of water inrush channels, are investigated. The results indicate that the water inrush source is the Ordovician limestone aquifer, which is connected by the karst collapse column to No. 16 coal seam; the fracturing zone that led to a water inrush occurs in front of the roadway excavation face where new fractures coalesced with the main fractured zone in the karst collapse column.

scholarly journals Evaluation on water bursting risk of working faces near collapse column during the mining process

2020 ◽  
Vol 198 ◽  
pp. 02003
Author(s):  
Yang Xue ◽  
Huang Jingwu ◽  
Wang Hua ◽  
Liang Maoliang ◽  
Li Wei ◽  
...  
Keyword(s):  
Coal Seam ◽  
Fracture Zone ◽  
Economic Loss ◽  
Mining Area ◽  
Mining District ◽  
Maximum Height ◽  
The West ◽  
Working Face ◽  
Collapse Column ◽  
Water Bursting

Collapse column water bursting occurs from time to time in the coal mining process of North China Type Coalfield in China, which causes great economic loss and personal injury. Therefore, great attention must be paid to the harm of collapse column. 1301 working face and 1306 working face in the west wing of No.1 Mining District of Zhangji Coal Mine in Shanxian County are close to No.2 collapse column. Water bursting risk evaluation must be carried out before mining two working faces to ensure safety production. On the basis of fully analyzing the geological and hydrogeological conditions of the 3up coal seam in the west wing of No.1 Mining Area, the "Three Zones(caving zone, water conducted fracture zone and sagging zone) Theory of Coal Seam Roof", "Strata Movement Theory" and "Water Bursting Coefficient Theory" were used respectively to calculate and evaluate the water bursting risk of No.2 collapse column during the course of mining the 1301 working face and 1306 working face. The results show that: firstly, in the process of mining the 1301 working face, the maximum height of the water conducted fracture zone at the closest position of 1301 working face to No.2 collapse column would be 60.20 m, the water bursting coefficient on the boundary of water conducted fracture zone would be 0.066~0.072 MPa/m, and the water bursting risk of the No.2 collapse column would be smaller; secondly, in the process of mining the 1306 working face, the maximum height of the water conducted fracture zone at the closest position of 1306 working face to No.2 collapse column would be 60.91 m, the water bursting coefficient on the boundary of water conducted fracture zone would be 0.057~0.089 MPa/m, and the water burst risk of the No.2 collapse column would be small. By August 31, 2020, the 1301 working face had been safely mined more than 200 meters long(exceeding over 120 m of the closest position in 1301 working face to No.2 collapse column), and the water bursting did not happen in the working face. This paper can provide a reference for the water prevention and control of similar collapse columns in coal mines.

scholarly journals Research on Characteristic Recognition and Dangerous Prevention While Mining through Collapse Column of Pansan Minefield,China

2021 ◽  
Author(s):  
Haitao Xu ◽  
hui yang ◽  
Wenbin Sun ◽  
Lingjun Kong ◽  
Peng Zhang
Keyword(s):  
Coal Seam ◽  
Water Inrush ◽  
Coal Pillar ◽  
Simulation Software ◽  
Coal Seams ◽  
Transient Electromagnetic ◽  
Working Face ◽  
Electromagnetic Detection ◽  
Floor Failure ◽  
Collapse Column

Abstract In order to find out the characteristics of geological isomer exposed in the mining process of 12318 working face in Pansan Mine and grasp its influence law on subsequent coal seams mining, the isomer was firstly determined as the collapse column by means of 3D seismic, transient electromagnetic detection, SYT detection and other methods, and its development characteristics, conductivity and water enrichment were identified.Then FLAC3D numerical simulation software was used to analyze the characteristics of vertical stress and plastic failure zone in different coal seams during mining.Finally, by comparing the ultimate failure depth of floor and the thickness of waterproof layer in the process of each coal seam directly pushing through the collapse column, the risk of water inrush and the prevention are analyzed.The results show that the exposed geological isomer is characterized by weak water-rich collapse column.Under the influence of the mining of the previous coal seam and the activation of the collapse column, the subsequent coal seam is in the low stress area before mining, which increases the floor failure and causes the activation of the collapse column more easily during mining.Coal 5# and 4# can be directly pushed through the collapse column, and coal pillar of sufficient width should be left for coal 1# to prevent the collapse column from activating water inrush.

Mining Design Optimization Research on the Northern Section of 8 Coal Seam in West No.1 Mining Area in Pansan Mine

2013 ◽  
Vol 634-638 ◽  
pp. 3394-3403
Author(s):  
Hua Wang ◽  
Chang Cai Fang ◽  
Yi Guo Shu ◽  
Li Xin Yang ◽  
De Fu Jiang ◽  
...  
Keyword(s):  
Coal Seam ◽  
Design Optimization ◽  
Mine Water ◽  
Water Inrush ◽  
Mining Area ◽  
Mine Area ◽  
Rock Pillar ◽  
Working Face ◽  
Coal Rock ◽  
Mining Design

Water in Lower Aquifer of Quaternary is one of the mine water inrush sources during working faces being mining in the Northern Section of 8 Coal Seam in West No.1 Mining Area. Water flowing fractured zone, F1 fault, F22-a fault and F48 fault are main water-conducting channels in mining. According to the analysis of geology and hydrographical geology of the mine area, and combined with “Water Prevention Regulation of Coal Mines” and “Regulations of pillar leaving and coal mining under building, water, railway and mail shaft and tunnel”, stope layout was optimized, i.e. the minimum waterproof coal(rock) pillar between working face and Lower Aquifer Quaternary is 70 meter, the waterproof coal(rock) pillar between working face and F1 fault, F22-a fault, F48 fault is 70~95 meter, 70~75 meter, 80~90 meter respectively. Each shallow waterproof coal (rock) pillar of fault is narrow at the top and tends to increasingly widen at the bottom.

scholarly journals Catastrophe Mechanism of Stress-Fissure Coupling Field in Mining Close Distance Seams in Southwest China

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Suo Jie ◽  
Li Zhen-hua ◽  
Huang Cun-han ◽  
Cao Zheng-zheng ◽  
Xu You-lin ◽  
...  
Keyword(s):  
Coal Seam ◽  
Southwest China ◽  
Water Inrush ◽  
Karst Cave ◽  
Coupling Field ◽  
Karst Caves ◽  
Working Face ◽  
Close Distance ◽  
Maximum Opening ◽  
Basic Roof

For the sake of studying the catastrophe mechanism of stress-fissure coupling field in mining close distance seams in southwest China, a test working face in Guizhou province in southwest China is adopted and researched by the methods of numerical calculation and similar experiment. When the working face advances to 180 m in 4# coal seam in a similar experiment, the overlying rock breaks to the central base plate of Yulongshan limestone, and the conductive fractures run through the Changxing limestone karst cave and Yulongshan limestone karst cave. When the 1402 working face advances to 350 m, the top of vertical karst caves in the middle of the model produces extrusion damage, forming a penetrating water inrush passage. When the 1402 working face advances to 480 m, the top slab of the working face comes under periodic weighting with the short step. Besides, the mining of 9# coal seam starts after 4# coal seam in mining close distance seams. When the working face in 9# coal seam advances to 340 m in numerical simulation, the maximum opening of the overburden fractures is 51.16 mm. The fractures in the roof are mainly caused by the periodic breaking and falling of the basic roof, connected with the floor fractures of 4# coal seam. When the working face in 9# coal seam advances to 500 m, the maximum opening of the overburden fracture is 93.09 mm. Specifically, as the working face advances, the opening of fracture in the roof after collapse of the basic roof periodically is mainly greater than 5 mm, and the compaction closure is mainly 1 mm-5 mm. The fractures in the gob floor are mainly 0.1 mm-1 mm, and the fracture opening of the collapsed rock mass in the gob is mainly 1 mm-5 mm and greater than 5 mm. The karst caves in the overburden reduce the periodic weighting step of working face and play a guiding role in the direction of fracture development and water inflow passage formation. The karst caves are connected to surface waterfall holes and trap pits, and atmospheric precipitation recharges the water in the caves. The research results can be treated as an important basis for the prevention and treatment for water inrush disaster in mining close distance seams in the karst area of southwest China.

scholarly journals Geological Structure Exploration of Karst Collapse Column and Evaluation of Water Insulation Properties of the Mud Part

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Shijian Yu ◽  
Jiyang Liu ◽  
Peng Bai ◽  
Hongtao Xu ◽  
Runshan He ◽  
...  
Keyword(s):  
Water Inrush ◽  
Splitting Method ◽  
Geological Structure ◽  
Karst Collapse ◽  
Electrical Characteristics ◽  
X Ray Diffraction ◽  
Working Face ◽  
Mineral Compositions ◽  
Collapse Column ◽  
Brazilian Splitting

In this study, the X5 KCC in Shiquan Coal Mine was investigated by means of controlled source audio magnetotelluric exploration and borehole television. In this way, the subsection geological structure of the KCC was obtained. Next, the geological and electrical characteristics of each part were analyzed, and it is concluded that the development status of the mud part under coal seam floor is the key part to judging whether water inrush will occur during working face recovery under aquifer pressure. Furthermore, the mineral compositions of purplish-red mudstone and lime mudstone were obtained by performing an X-ray diffraction experiment on the KCC interstitial materials. On this basis, the water insulation properties of the mud part were qualitatively evaluated. Finally, the tensile strength of the mud part was obtained by the Brazilian splitting method, and the water insulation ability of the mud part at the periods when the tunneling roadway and the working face passed the KCC was calculated, respectively. The research results boast guiding significance for safe recovery of the working face passing KCCs under aquifer pressure.

scholarly journals Exploration and application of directional long boreholes in coal measure strata

2021 ◽  
Vol 261 ◽  
pp. 03003
Author(s):  
Qin Ke ◽  
Peng Dong ◽  
Duan Huijun
Keyword(s):  
Coal Seam ◽  
Water Inrush ◽  
Critical Value ◽  
Coal Measure ◽  
Bottom Plate ◽  
Drain Water ◽  
Safe Water ◽  
Working Face ◽  
Water Hazard ◽  
Insulation Thickness

two roadways in adjacent working face of Baode Mine may have the risk of water inrush at the same time, so it is necessary to construct long borehole to cover the roadway excavation. On the basis of the hydrogeological conditions of the mine, the safe water insulation thickness and water inrush coefficient of coal seam No .8 are calculated. The results show that the water inrush coefficient is 0.035-0.037 MPa/m, which is less than the critical value 0.06 MPa/m and the bottom plate has no sudden water hazard. In the construction of No .10 coal seam, the directional long borehole is used to detect whether there is a hidden structure communicating with the floor limestone and to drain water. The test shows that there is no effluent phenomenon in the borehole, which proves that there is no hidden structure in No .10 coal seam.

Computational fluid dynamics optimization of gas drainage technology in gas-mining areas

2021 ◽  
pp. 014459872110635
Author(s):  
Wei Zhao ◽  
Wei Qin
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Coal Seam ◽  
Field Tests ◽  
Mining Area ◽  
Engineering Practice ◽  
Horizontal Distance ◽  
Gas Drainage ◽  
Working Face ◽  
Gas Seepage

Coal mining results in strata movement and surrounding rock failure. Eventually, manual mining space will be occupied by the destructed coal rock, making it difficult to conduct field tests of the coal seam to explore gas seepage and transport patterns. Therefore, computational fluid dynamics (CFD) numerical computation is an important tool for such studies. From the aspect of gas pre-drainage, for layer-through boreholes in the floor roadway of the 8,406 working face in Yangquan Mine 5 in China, reasonable layout parameters were obtained by CFD optimization. For effectively controlling the scope of boreholes along coal seam 9 in the Kaiyuan Mine, CFD computation was performed. The results revealed that the horizontal spacing between boreholes should be ≤2 m when a tri-quincuncial borehole layout is used. Optimization of the surface well position layout for the fault structure zone in the Xinjing Mine of the Yangquan mining area indicated that the horizontal distance between the surface well and the fault plane should be <150 m. From the aspect of gas drainage with mining-induced pressure relief, CFD computation was performed for pressure-relieved gas transport in the K8205 working face of Yangquan Mine 3. The results showed that forced roof caving should be used before the overhang length of hard roof reaches 25 m in the K8205 working face to avoid gas overrun. From the aspect of gas drainage from the abandoned gob, surface well control scopes at different surface well positions were computed, and an O-ring fissure zone is proposed as a reasonable scope for the surface well layout. CFD computation has been widely applied to coal and gas co-extraction in the Yangquan mining area and has played a significant role in guiding related gas drainage engineering practice.

scholarly journals Damage Characteristics and Mechanism of a 2010 Disastrous Groundwater Inrush Occurred at the Luotuoshan Coalmine in Wuhai, Inner Mongolia, China

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 655 ◽  
Author(s):  
Fangpeng Cui ◽  
Qiang Wu ◽  
Chen Xiong ◽  
Xiang Chen ◽  
Fanlan Meng ◽  
...  
Keyword(s):  
Coal Seam ◽  
Inner Mongolia ◽  
In Situ Stress ◽  
Economic Losses ◽  
Karst Collapse ◽  
Great Effort ◽  
Groundwater Inrush ◽  
Collapse Column ◽  
Great Damage

On 1 March 2010, a disastrous groundwater inrush occurred at the Luotuoshan coalmine in Wuhai (Inner Mongolia, China). Great effort was taken during the post-accident rescue. However, triggered by a large amount of groundwater rushed in from the Ordovician limestone aquifer underlying the No.16 coal seam through the fractured sandy claystone and the karst collapse column, it caused great damage, including 32 deaths and direct economic losses of over 48 million yuan. The groundwater inrush originated from the floor heave in the air return gallery of the No.16 coal seam. The peak inflow rate was 60,036 m3/h. The gallery excavation under conditions caused by the incompletely recognized hydrogeological environment induced the accident. The unidentified spatial distribution of the karst collapse column triggered the accident directly. The high-pressure groundwater accumulated in the collapse column and the gallery excavation, which caused the redistribution of the in situ stress, contributing to progressive fractures in the floor of the No. 16 coal seam. Eventually, an intensive water-conductive passage consisting of the fractured floor and the karst collapse column formed. Administratively/technically, that mandatory regulations on gallery excavation were not carried out which contributed the accident. Moreover, the poor awareness about groundwater inrush recognition and quick remediation also contoirbuted to the disastrous extent of the accident.

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