scholarly journals Study on the Law of Surface Cracks While Coal Mining in the Thin Bedrock and Thick Unconsolidated Layer of Yu-Shen-Fu Mining Area

2018 ◽  
Vol 53 ◽  
pp. 03040
Author(s):  
Wu Zuoqi ◽  
Wang Guoku ◽  
Zhao Liqin
Keyword(s):  
Coal Mining ◽  
Ground Surface ◽  
Mining Area ◽  
Dynamic Evolution ◽  
Surface Cracks ◽  
Whole Process ◽  
Thin Bedrock ◽  
The Law ◽  
Mining Face ◽  
Overlying Strata

The law of surface cracks caused by coal mining in ther thin bedrock and thick unconsolidated layer was studied in Yu-Shen-Fu mining area. The crack development in the overlying strata of the coal mining face was detected by drilling survey technology, the whole process of the ground surface crack dynamic evolution was carried out by similar material simulation, and the law of surface cracks evolution was verified by on-site tracking measurement. The study reached the regulation of the overlying strata failure and dynamic evolution of surface cracks caused by coal mining under thin bedrock and thick unconsolidated layer in Yu-Shen-Fu mining area, which can provide theoretical support for the ecological restoration of western mining area.

scholarly journals Movement Laws of Overlying Strata above a Fully Mechanized Coal Mining Face Backfilled with Gangue: A Case Study in Jiulishan Coal Mine in Henan Province, China

2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Zhengkai Yang ◽  
Zhiheng Cheng ◽  
Zhenhua Li ◽  
Chunyuan Li ◽  
Lei Wang ◽  
...  
Keyword(s):  
Coal Mining ◽  
Main Roof ◽  
Surrounding Rock ◽  
Surface Subsidence ◽  
Key Strata ◽  
Key Stratum ◽  
Mining Face ◽  
Failure Depth ◽  
Gangue Backfilling ◽  
Overlying Strata

The aim of this study is to obtain movement laws of overlying strata above a fully mechanized coal mining face backfilled with gangue and solve the problem of surface subsidence during coal mining. This study was carried out based on gangue backfilling mining of Jiulishan Coal Mine (Jiaozuo City, Henan Province, China) from the perspectives of deformation of backfilled gangue under compaction, surrounding rock of a stope, and activities of key strata. The method combining with rock mechanics, viscoelastic mechanics, control theory of rock mass under mining, and numerical simulation was used based on physical and mechanical characteristics of backfilled gangue. On this basis, the research analyzed the temporal-spatial relationships of activities of surrounding rock of the stope, compressive deformation of backfilling body, failure depth of the floor, deformation characteristics of the main roof with laws of surface subsidence. The movement characteristics of overlying strata above the fully mechanized coal mining face backfilled with gangue and the traditional fully mechanized mining face were compared. It is found that, under the same conditions of overlying strata, movement laws of overlying strata are mainly determined by the mining height of coal seams and the heights of a caving zone and a fracture zone are nearly linearly correlated with the mining height. Through analysis based on thin-plate theory and key stratum theory, the location of the main roof of the fully mechanized coal mining face backfilled with gangue in coal seams first bending and sinking due to load of overlying strata was ascertained. Then, it was determined that there are two key strata and the main roof belongs to the inferior key stratum. By using the established mechanical model for the main roof of the fully mechanized coal mining face backfilled with gangue and the calculation formula for the maximum deflection of the main roof, this research presented the conditions for breaking of the main roof. In addition, based on the theoretical analysis, it is concluded that the main roof of the fully mechanized coal mining face backfilled with gangue does not break, but bends. The numerical simulation results demonstrate that, with the continuous increase of strength of backfilled gangue, the stress concentration degree of surrounding rock reduces constantly, so does its decrease amplitude. Moreover, the compressive deformation of backfilling, failure depth of the floor, and bending and subsidence of the main roof continuously decrease and tend to be stable. The mechanical properties of backfilling materials determine effects of gangue backfilling in controlling surface subsidence. Gangue backfilling can effectively control movement of overlying strata and surface subsidence tends to be stable with the increase of elastic modulus of gangue.

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.

New Technology of Surface Subsidence Control and Environmental Protection Research in Coal Mining Region

2014 ◽  
Vol 675-677 ◽  
pp. 1385-1394
Author(s):  
Cheng Rong Jiang ◽  
Liu Yang ◽  
Hao Xie ◽  
Hua Yi Huang ◽  
De Ke Sun
Keyword(s):  
Coal Mining ◽  
New Technology ◽  
Mining Area ◽  
Industrial Test ◽  
Surface Subsidence ◽  
High Concentration ◽  
Geological Conditions ◽  
Surface Subsidence Control ◽  
Fissure Water ◽  
Overlying Strata

In combination with the geological conditions of Tie'er mining area in Tangshan coal mining, this paper not only analyzes the evolution of overlying strata structure in stope and the development law of overlying strata separation, also proposes a new continuous grouting technology with large flow and high concentration slurry. The industrial test showed that, when the grout-mining ratio of the whole mining area is 25.3%, the reducing subsidence ratio is 51.5%, the effect of reducing the surface subsidence is good. According to the chemical analysis of water quality ingredients of slurry, the test result showed, heavy metals contents in fly-ash slurry water do not exceed the standard, which has no bad effect on the fissure water in the bedrock.

Research on the Overlying Strata in Full-Mechanized Coal Mining of Datong Jurassic Coal Multi-Layer Goaf

2012 ◽  
Vol 616-618 ◽  
pp. 402-405 ◽  
Author(s):  
Hong Chun Xia ◽  
Guo Sheng Gao ◽  
Bin Yu
Keyword(s):  
Coal Seam ◽  
Coal Mining ◽  
Coal Pillar ◽  
Mining Area ◽  
Mechanics Model ◽  
Roof Structure ◽  
Geological Conditions ◽  
Seam Mining ◽  
The Impact ◽  
Overlying Strata

According to the specific geological conditions in themulti-layer worked-out areas of Yongding coal seam, by the methods of integration of theoretic analysis, numerical value calculation and so on, we studied movement law of Overlaying Strata and influence of coal pillar in Coal seam mining, obtained the basic law of the overlying strata movement in multiplayer, provides a theoretical basis for the safe and efficient exploitation of the success of multiplayer. Many mining area in China is mining of closed distance coal seam group, By the impact of coal seam in the overlying, face and the tunnel roof structure will be different injury in sub-coal seam mining, Roof structure has changed greatly, even damage and easily take the roof leakage, When the the goaf communication with the overlying coal seams, caused by the induced secondary disasters such as face air leakage, Therefore, exploitation of the law of motion of the overlying strata in the multiplayer is a pressing problem. Exploitation multiplayer seam few theoretical and technical foundation at home and abroad, affecting the validity of the mining, rationality. although a lot of research on theory and technology of coal mining over the years[1~5], But it was not able to an overall comprehensive analysis of upper goaf adjacent goaf and overlying the coal pillar and present mining face, create a dynamic structural mechanics model, which is likely to cause the occurrence of disasters.

scholarly journals Pressure-Arching Characteristics in Roof Blocks during Shallow Coal Mining

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Yanhai Zhao ◽  
Shuren Wang ◽  
Paul Hagan ◽  
Lianwei Ren ◽  
Zhengsheng Zou
Keyword(s):  
Coal Mining ◽  
Mining Area ◽  
Horizontal Stress ◽  
Linear Distribution ◽  
Arch Models ◽  
Thick Coal Seam ◽  
Roof Structure ◽  
Large Mining Height ◽  
Mining Face ◽  
Nonlinear Distribution

To reveal the performance of the stepped subsidence and the strong roof weighting during shallow coal mining, taking the fully mechanized mining face with large mining height in the Shendong mining area in China as the engineering background, theoretical analysis and numerical simulation were used to analyze the pressure-arching effect of the hanging roof blocks. Three typical pressure-arch models of the roof structure were proposed, such as the symmetrical pressure-arch of two key blocks, the step pressure-arch of multiple key blocks, and the rotative pressure-arch of multiple key blocks. Results indicate that the horizontal stress displays a nonlinear distribution at the abutments of the symmetrical pressure-arch, and there is a linear distribution of horizontal stress with a higher peak value at the midspan of the pressure-arch. The high horizontal stress at the arch abutment is necessary to form the rotative pressure-arch of multiple key blocks. The horizontal stress is relatively less at the arch abutment of the step pressure-arch structure. The main key block is easier to slide in this structure as the boundary horizontal stresses display the nonlinear distribution. The results are of instructive significance for roof weighting forecast and strata control during shallow horizontal mining for a thick coal seam.

Ground deformations associated with underground coal-mining observed by Sentinel-1 SAR images in vegetated area

2020 ◽  
Author(s):  
Yonghong Zhang ◽  
Hong’an Wu ◽  
Yong Luo ◽  
Yonghui Kang ◽  
Hongdong Fan
Keyword(s):  
Winter Wheat ◽  
Coal Mining ◽  
Large Scale ◽  
Central Government ◽  
Underground Mining ◽  
Mining Area ◽  
Least Square ◽  
Whole Process ◽  
Ground Deformations ◽  
Multi Temporal

<p>Coal is the largest energy source for China, and over 90% coal production in China is from underground mining. However, underground mining usually trigger large-scale ground deformations, which tend to develop as hazards. Therefore, the central government of China issued the “green mine” policy in 2017, which requires to strictly implement scientific and orderly exploitation and keeping the disturbance to the mining area and surrounding environment within the limits of sustainable development in the whole process of coal mining. This policy necessitates accurate monitoring of ground deformations induced by underground mining. Satellite Interferometric SAR (InSAR), especially the multi-temporal InSAR techniques have been successfully used to monitor deformations associated with underground mining. But temporal decorrelation still remains a big challenge because many underground mining takes place beneath farmland or forested region. Given the advantages of Sentinel-1 (S-1) in short revisit time, small baselines and free accessibility, underground mining deformations can be monitored somehow with S-1 InSAR in vegetated areas. In this research we report such an application in an underground coal-mine site located in Xuzhou, Jiangsu province of China. Four working panels are investigated</p><p>The working panels are all beneath farmland where winter wheat is sowed before the end of October and reaped around next late May, then corn or rice is planted during the coming summer season from June to September. Therefore the C-band S-1 interferograms can keep good coherence only when both images are acquired in the period of late October to next early April (this period is called coherent period thereafter) when the newly planted winter wheat is in its early growing stage. Three subsets of S-1 images acquired during three consecutive coherent periods  are used to generate mining-induced ground deformations.</p><p>During each coherent period, all of the interferograms with 12-day separation and some of the interferograms with 24-day separation and good coherence are selected and phase-unwrapped. Then these two sets of unwrapped interferograms are stacked, and finally the temporal deformations along SAR line-of-sight (LOS) are calculated under the least square principle. The temporal and spatial characteristics of the LOS deformation time series (DTS) are analyzed by considering extraction stage and extraction parameters of the working panel. Based on the analysis, we can diagnose whether the underground exploitation overstepped its designed boundary, or whether the working panel has been exploited for longer time than the designed extraction period.</p><p> </p>

Study on Fully-Mechanized Top Coal Caving Mining under Water Body with Shallow Overburden and Thin Bedrock

2013 ◽  
Vol 734-737 ◽  
pp. 644-649 ◽  
Author(s):  
Lei Li ◽  
Zhi Guo Liu ◽  
Pei Pei Chen ◽  
Gui Liu
Keyword(s):  
Numerical Simulation ◽  
Coal Mining ◽  
Water Body ◽  
Mining Area ◽  
Research Area ◽  
Water Inflow ◽  
Geological Condition ◽  
Geological Model ◽  
Simulation Based ◽  
Thin Bedrock

Based on the geological condition of MaHuangliang coal in the Yushen mining area, the paper systematically studied the overburden's destructiverules of fully-mechanized top coal caving, and established hydro-geological model of research area by using GMS numerical simulation. Based on the model, the paper predicted the water inflow of different aquifer, analyzed the influence of aquifer to coal mining, and introduced the technical plans about fully-mechanized top coal caving mining under water body with shallow overburden and thin bedrock.

Sign in / Sign up

Export Citation Format

Share Document