scholarly journals Analysis of Overlying Strata Movement and Disaster-Causing Effects of Coal Mining Face under the Action of Hard Thick Magmatic Rock

Processes ◽  
2018 ◽  
Vol 6 (9) ◽  
pp. 150 ◽  
Author(s):  
Quanlin Wu ◽  
Quansen Wu ◽  
Yanchao Xue ◽  
Peng Kong ◽  
Bin Gong
Keyword(s):  
Coal Seam ◽  
Fracture Zone ◽  
Magmatic Rock ◽  
Ratio Test ◽  
Large Area ◽  
Deformation And Failure ◽  
Key Strata ◽  
Magmatic Rocks ◽  
Working Face ◽  
Bed Separation

When the hard and thick key strata are located above the working face, the bed separation structure is easy to be formed after mining because of the high strength and integrity of the hard and thick key strata and the initial breaking step is large. After the hard, thick strata are broken, the overburden will be largely collapsed and unstable in a large area and the dynamic disaster is easily induced. In this study, considering the fundamental deformation and failure effect of coal seam, the development law of the bed separation and the fractures under hard and thick magmatic rocks and the mechanism of breaking induced disaster of hard and thick magmatic rocks are studied by similar simulation tests. The results of the study are as follows: (1) The similar material ratio of coal seam is obtained by low-strength orthogonal ratio test of similar materials of coal seam, that is, cement:sand:water:activated carbon:coal = 6:6:7:1.1:79.9. (2) The magmatic rocks play a role in shielding the development of the bed separation, which makes the bed separation beneath the magmatic rock in an unclosed state for a long time, providing space for the accumulation of gas and water. (3) The distribution pattern of the fracture zone shows different shapes as the advancing of working face and the fracture zone width of the rear of working face coal wall is larger than that of the front of the open-off. (4) The breaking of magmatic rocks will press the gas and water accumulated in the bed separation space below to rush towards the working face along the fracture zone at both ends of the goaf. The above results are verified through the drainage borehole gas jet accident in the Yangliu coal mine. The research results are of great significance for revealing the occurrence process of dynamic disasters and adopting scientific and reasonable preventive measures.

scholarly journals Study on the Development Height of Overburden Water-Flowing Fracture Zone of the Working Face

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Ke Ding ◽  
Lianguo Wang ◽  
Wenmiao Wang ◽  
Kai Wang ◽  
Bo Ren ◽  
...  
Keyword(s):  
Coal Seam ◽  
Fracture Zone ◽  
Tensile Deformation ◽  
Drainage Water ◽  
Future Research ◽  
Overburden Rock ◽  
Material Transfer ◽  
Rock Stratum ◽  
Working Face ◽  
Sandstone Rock

Mining-induced fractures in underground coal mining face affect the stability of overburdens and provide preferential channels for water and material transfer in the underground environment. Therefore, to study the development of water-flowing fracture zones in overburdens of working face and goaf is of great significance for roof control, gas drainage, water resistance, disaster reduction, and efficient mining from the mining. In this study, a new method for predicting the development of overburden water-flowing fracture zone height (DHOWFFZ) was proposed based on the characteristics of overburden rock in No. 3 coal seam of Xin’an Coal Mine. First, the stope of No. 3 coal seam exhibits a rock stratum structure of mudstone and sandstone overlapping. Considering this characteristic, the overburden strata of No. 3 coal seam are divided into several “mudstone-sandstone” rock stratum groups. Furthermore, the ultimate tensile deformation of soft rock is greater than that of hard rock. It is proposed to judge the development degree of penetrating fracture in each rock stratum by adopting the elongation rate of mudstone intermediate layer. Meanwhile, the DHOWFFZ of “mudstone sandstone” composite rock stratum structure in the 3402 working face of No. 3 coal seam is calculated to be smaller than 43.1 m according to the actual situation. Finally, the DHOWFFZ in the 3402 working face was measured in the field, which verifies the rationality of the new DHOWFFZ prediction method. The research results provide new ideas for the prediction of DHOWFFZ and are helpful for future research in related fields.

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

Energies ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 102 ◽  
Author(s):  
Peng Li ◽  
Xufeng Wang ◽  
Wenhao Cao ◽  
Dongsheng Zhang ◽  
Dongdong Qin ◽  
...  
Keyword(s):  
Coal Seam ◽  
Fracture Zone ◽  
Spatial Relationships ◽  
Thick Coal Seam ◽  
Key Strata ◽  
Seam Mining

Gas Control Technology for Fully Mechanized Face of Outburst Coal Seam with Hard Roof during Initial Caving

2011 ◽  
Vol 347-353 ◽  
pp. 974-978
Author(s):  
Ju Gen Fu ◽  
Wei Wu ◽  
Gen Yong Hua
Keyword(s):  
Coal Seam ◽  
Shock Pressure ◽  
Control Technology ◽  
Large Area ◽  
Hard Roof ◽  
Working Face ◽  
Initial Release ◽  
Gob Area ◽  
Outburst Coal Seam ◽  
Presplit Blasting

In the fully mechanized working face, with working face forward, gob area become bigger and bigger, when the top area reach a certain span ,roof in gob suddenly cave, outspreading a large quantity of mine gas, easy to cause the gas overrun and gas accidents. In addition, shock pressure which is caused when large area roof cave, easily causing casualties and damage of equipment. This paper introduces Pan three Coal mine 17171(1) ore advance of fully mechanized working face presplit blasting, rotating stoping and comprehensive extraction technologies, which successfully solve the roof management and the gas problems during initial release, achieving good security benefits.

scholarly journals Determining the Layout Parameters of the Gas Drainage Roadway: A Study for Sima Coalmine China

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Zhiliu Wang ◽  
Bo Liu ◽  
Yanhui Han ◽  
Zhaoyang Li ◽  
Yingjie Cao ◽  
...  
Keyword(s):  
Coal Seam ◽  
Fracture Zone ◽  
Calculation Method ◽  
Analytical Calculation ◽  
Horizontal Distance ◽  
Gas Drainage ◽  
Working Face ◽  
Scale Modelling ◽  
Modelling Experiment ◽  
Drainage Effect

To determine the layout parameters of the gas drainage roadway (GDR) serving for the working face, an analytical calculation method of fracture zone and the modelling experiment were adopted, and the overburden fissure induced by mining and the height of fracture zone were analyzed. For the research on the distribution of fracture zone by analytical calculation method, the multiple factors influencing the failure mode of strata and the height of fracture zone were considered. The #1207 working face in Sima mine was taken as an engineering background, and the layout parameters of GDR were given by analyzing the height of fracture zone. Combining the results obtained by analytical calculation and scale modelling experiment, the suggested height of GDR was 10.7–32.8 m away from the coal seam roof, and the projection distance of GDR in the horizontal was within the range of 0–35 m from the airway. By monitoring the gas drainage effects in different heights away from coal seam roof in #1207 working face and in different horizontal distances away from the ventilation roadway in the #1211 working face, the results showed that the optimal height was 17.5–22 m away from coal roof, and the optimal horizontal distance was 17–21 m away from airway for GDR. The gas drainage effect of GDR indicated that the proposed parameters are scientific and reasonable.

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 Study on Deformation and Failure Characteristics of Weak Cemented Roof in Shallow and Extra Thick Coal Seam Mining

2021 ◽  
Author(s):  
Chang Liu ◽  
Pingsong Zhang ◽  
Duoxi Yao ◽  
Yuancaho Ou ◽  
Yutong Tian
Keyword(s):  
Coal Seam ◽  
Apparent Resistivity ◽  
Maximum Height ◽  
Geoelectric Field ◽  
Electrical Method ◽  
Deformation And Failure ◽  
Fractured Zone ◽  
Working Face ◽  
Seam Mining ◽  
Loose Layer

Abstract Detecting the development height of water flowing fractured zone in the roof of coal seam is of great significance for the roof safety of working face with developed sandstone and thick loose layer. This paper analyzes the influence of the induced polarization effect of electrode on the traditional single-mode parallel electrical method. In order to avoid this interference, the dual-mode parallel electrical method is applied to monitor the roof deformation and failure of a coal mine in Ordos Basin. The monitoring results show that: under the influence of mining, the change of geoelectric field of coal seam roof is dynamic, the apparent resistivity of initial mining fracture is high, the apparent resistivity of surrounding rock water filling mining fracture is low, and the apparent resistivity of fracture water flowing to goaf is high again. According to the characteristics of geoelectric field, the maximum height of water flowing fracture zone is 122 M; The average mining coal thickness of the working face is 11 m, and the fracture / mining thickness ratio is 11.1. The results of plastic zone show that the maximum height of water flowing fractured zone above the working face is 122 m, which is consistent with the test results. The vertical stress response characteristics of roof monitoring points are zonal. Under the influence of mining, the loose layer near the surface above the working face is cracked. The edge type ground fissures exist for a long time, and there are a series of geological problems such as soil erosion, ground subsidence.

scholarly journals Recognition and Prevention of Bed Separation Water: Based on Trapezoid Platform Model

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Ru Hu ◽  
Jiwen Wu ◽  
Xiaorong Zhai ◽  
Wei Liu
Keyword(s):  
Plate Theory ◽  
Water Inrush ◽  
Control Measures ◽  
Key Strata ◽  
Working Face ◽  
Bed Separation ◽  
Prevention And Control Measures ◽  
Evolutional Process ◽  
And Control ◽  
Overlying Strata

In recent years, bed separation water inrush, as a new type of water disaster, has posed serious threat to mining safety in China’s many coal mines. This study focused on periodic water inrush accidents in the No. 7335 working face owned by Xuzhuang Coal Mine, Jiangsu Province, China. Based on the theory of key strata, the formation positions of the separation layer in the overlying strata were first identified; next, the trapezoid platform model of the fracture of the overlying strata was introduced for illustrating the evolutional process of the bed separation space and accurately calculating the position and the geometrical morphology of the bed separation space. On that basis, the relation between the fracture of the overlying stratum and the inrush of bed separation water was revealed with the use of the plate theory. Moreover, the prevention and control measures of the bed separation water were formulated. Research show that the arrangement of the diversion drilling holes can successfully eliminate the threat of the bed separation water to the lower working face.

scholarly journals Research on the Roof Advanced Breaking Position and Influences of Large Mining Height Working Face in Shallow Coal Seam

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1685
Author(s):  
Qingxiang Huang ◽  
Yanpeng He ◽  
Feng Li
Keyword(s):  
Coal Seam ◽  
Field Measurement ◽  
Physical Simulation ◽  
Main Roof ◽  
Key Strata ◽  
Working Face ◽  
Measurement Results ◽  
Large Mining Height ◽  
Shallow Coal Seam ◽  
Mining Height

The large mining height (LMH) in shallow coal seam has been widely applied in the Shenfu coalfield, China. The dynamic load is obvious, and the rib spalling is serious when the LMH working face concerns roof weighting. The advanced breaking position of the roof affects the strength of the ground pressure when the roof is broken. Firstly, based on a large number of actual measurements and physical simulation experiments, the rock formation in the fall zone, where the articulated structure cannot be articulated between the coal seam and the main roof, is called the equivalent immediate roof (EIR). When the mining height increases, the thickness of the EIR increases non-linearly. Next, based on the theory of “elastic foundation beam”, a mechanical model for the advanced breaking of the roof is established in shallow coal seam, and the calculation equation for the advanced breaking position of the roof is given; then, designed and carry out boreholes of the no. 22201 working face in the Zhangjiamao Coal Mine. The theoretical calculation of key strata results (5.6–6.9 m) are in the range of field measurement results (5–8 m). According to the field measurement results, the roof movement of the LMH working face is ahead of the roof weighting. Finally, we define the thickness of EIR and the mining height ratio as the immediate mining ratio ki, which affects the degree of filling of the goaf and determines the structural form of the main roof. When the ki is small, the goaf is fully filled; when the ki is large, the goaf is fully filled. Under the same conditions, different filling rate conditions will form different roof structures. Results of this research can be helpful to control roof weighting and provide early warning of possible safety problems related to the LMH working face in shallow coal seam.

Forecasting Collapse and Monitoring of the Main Roof Current State in Working Faces of Coal Mines with Shallow Seams

2021 ◽  
pp. 13-18
Author(s):  
A.I. Nedzelskiy ◽  
◽  
I.V. Shnayder ◽  
E.S. Lapin ◽  
◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Dust ◽  
Coal Mines ◽  
Main Roof ◽  
Coarse Grained ◽  
State Monitoring ◽  
Large Area ◽  
Current State ◽  
Working Face ◽  
Dip Angle

Main roof state monitoring and assessment of the roof hanging influence on the coal seam in working face of the coal mines with medium thickness seams with dip angle varying from 0 to 35° using a long-pillar development system along strike and uprising with roof control by complete collapse and abandonment of inter-main pillars a technically difficult task and currently unsolvable by tools. The main roof, composed of fine-grained gray sandstones, coarse-grained siltstones or interbedding of siltstones with sandstones, with average strengths of layers of about 30–40 MPa, is predicted to be moderately collapsing, and more than 50 MPa as difficult to collapse over a large area of coal seam spread. Hanging of the main roof with subsequent uncontrolled collapse can lead to the displacement of methane accumulating in the waste space into the face and provoke an explosion, fire or other emergency. It should be noted that the urgency of the problem is due to the fact that when large masses of the roof collapse during the lava retreat, an instantaneous release of large volumes of air from the collapsed space, accompanied by the release of methane and coal dust, occurs, which has repeatedly led to accidents. The article discusses the prediction of collapse and main roof current state monitoring in the working faces of coal mines with a shallow bedding by seismic method. Using «Mikon-GEO» as a seismic prediction system in coal mines and pits allows to make risks manageable and accounted.

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