scholarly journals Overlying strata movement with ground penetrating radar detection in close-multiple coal seams mining

2019 ◽  
Vol 15 (8) ◽  
pp. 155014771986985 ◽  
Author(s):  
Yang Li ◽  
Jiachen Wang ◽  
Yiding Chen ◽  
Zhipeng Wang ◽  
Jianpeng Wang
Keyword(s):  
Coal Seam ◽  
Ground Penetrating Radar ◽  
Longwall Mining ◽  
The United States ◽  
Coal Seams ◽  
Strata Movement ◽  
Longwall Panel ◽  
Ground Penetrating ◽  
Overlying Strata Movement ◽  
Overlying Strata

Longwall mining is a productive mining method that has been widely used in China, the United States, Australia, and Europe. However, due to the subsidence caused by coal mining activities, the phenomenon is complex, longwall mining brings the overburden movement issues accompany with the coal recovery. In subsidence trough, the resulting strata and surface ground movements are regarded as largely contemporaneous with mining, producing more or less direct effects of natural ecology. Ground penetrating radar has been widely used in geological hazard detection due to its high precision, but it is rarely employed in underground measuring the overlying strata movement above the longwall panel. In this article, there are five close-multiple coal seams (5#, 7#, 8#, 9#, 12# seams) within 70 m distance to be monitored in Qian Jiaying coal mine of Kailuan Coal Company in Hebei province. The 7#, 8#, 9#, 12# coal seams were already excavated in sequence. So the 5# coal seam is overmining above the gobs of four coal seams at the top. The ZTR12-series ground penetrating radar equipment is used to detect the development of fractures under the floor of the 5# coal seam. The ZTR12-series ground penetrating radar system has the capability of large depth detection and explosion proof to adapt to the working environment of underground coal mines and can realize fine detection and accurate identification. The maximum detection distance of reflection method can reach 50 m. The measurement results show that the 5# coal seam is in the fracture zone above the gobs of four coal seams, and the caved zone of lower coal seam develops to fine sandstone of the 5# coal seam floor. The ground penetrating radar has shown much promise in the detection of overlying strata movement.

scholarly journals Overlying Strata Movement Laws Induced by Longwall Mining of Deep Buried Coal Seam with Superhigh-Water Material Backfilling Technology

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Fangtian Wang ◽  
Qi Ma ◽  
Gang Li ◽  
Chengguo Wu ◽  
Guangli Guo
Keyword(s):  
Coal Seam ◽  
Field Experiments ◽  
Longwall Mining ◽  
Ecological Environment ◽  
Water Volume ◽  
Mine Pressure ◽  
Strata Movement ◽  
Coal Resources ◽  
Overlying Strata Movement ◽  
Overlying Strata

The “Three Under Mining” (mining under the buildings, the railways, and the waters) coal resources are stored in the central and eastern China. Many large-scale mine disasters occurred due to overburden strata movement and surface subsidence. Longwall mining with superhigh-water material backfilling technology has been improved efficiently to prevent the underground disasters and protect the surface ecological environment. Since underground mine pressure behavior and overlying strata movement are influenced by the backfilling strength and backfilling rates, rational design of backfilling parameters is key to realize the green mining of deep buried coal seams. Based on the combination of geological and production conditions of a deep buried coal seam with composite beam theory, the roof fracture distance was analyzed. The software of UDEC was used to simulate the overlying strata movement laws affected by the different backfilling strength and backfilling rates. With the comparative analysis of the vertical displacement movements and the vertical stress distributions, the reasonable filling rate and water volume fraction were determined to be 90% and 95%, respectively. According to the field experiments, the underground dynamic load was low enough for the safe mining, and the village building can be kept in a stable state with the application of the backfilling technology. The research results in a scientific basis for the coordinated development between the safe and efficient mining of deep buried coal resources and protection of the surface ecological environment.

scholarly journals The Study of Key Stratum Location and Characteristics on the Mining of Extremely Thick Coal Seam under Goaf

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Gaochuan Guo ◽  
Yongkang Yang
Keyword(s):  
Coal Seam ◽  
Longwall Mining ◽  
Maximum Principal Stress ◽  
Engineering Practice ◽  
Coal Seams ◽  
Thick Coal Seam ◽  
Key Strata ◽  
Key Stratum ◽  
Arch Structure ◽  
Overlying Strata

The basis of traditional ground pressure and strata control techniques is the key strata theory, wherein the position of the key stratum can easily be determined for coal seams with regular thickness and without goaf. However, in the case of mining ultrathick coal seams underneath goaf, the traditional methods used for the calculation of key stratum position need to be improved in order to account for the additional coal seam thickness and the presence of an upper goaf. This study analyzed the failure height and collapse characteristics of overlying strata during excavation for determining the structure of the failed overlying strata. The results indicate that the intercalation and overlying strata gradually evolve into a large “arch structure” and a small “arch structure” during longwall mining, respectively. A mechanical model of the bearing characteristics of the interlayer key strata structure was established according to the structure of the intercalation rock layer, which is a hinged block structure. The results of the model indicate that the maximum principal stress occurs when the key strata portion of the arch structure bears the overlying load. Consequently, the movement and position of the interlayer key strata can be evaluated throughout the mining process of the ultrathick coal seams underneath goaf. This method was used to determine the position of interlayer key stratum of overlying strata in Xiegou coal mine. And the results agree with that of the engineering practice. The results are significant to determine the key strata position during ultrathick coal seam underneath goaf longwall mining.

The Application of Similar Material in the Simulation of Overlying Strata Movement in High Inclined Seam in Dongbaowei Mine

2012 ◽  
Vol 600 ◽  
pp. 194-198 ◽  
Author(s):  
Ming Ming Wen
Keyword(s):  
Coal Seam ◽  
Reference Value ◽  
Geological Condition ◽  
Similar Material ◽  
Strata Movement ◽  
Support Measures ◽  
Working Face ◽  
Overlying Strata Movement ◽  
Similar Material Simulation ◽  
Overlying Strata

Studying on the characteristics of the overlying strata movement in high inclined coal seam, the similar material is applied in the simulation model which was built based on the similar material simulation theory and high inclined seam geological condition of Dongbaowei coal mine. The picture and displacement of overlying strata were obtained from the similar material simulation. As a result, the characteristics of the fracture and movement of overlying strata above the full mechanized working face in high inclined seam. This paper proposes some support measures to improve the safety of the working face. These provide significance theoretical guidance and reference value for other working face in high inclined seam.

scholarly journals The influence of distant coal seam edges on seismic hazard during longwall mining

2020 ◽  
Author(s):  
Łukasz Wojtecki ◽  
Iwona Gołda ◽  
Maciej J. Mendecki
Keyword(s):  
Coal Seam ◽  
Longwall Mining ◽  
Mining Area ◽  
Simultaneous Increase ◽  
Coal Seams ◽  
Upper Silesian Coal Basin ◽  
Longwall Panel ◽  
Mining Works ◽  
Seam Mining ◽  
Mining Tremors

Abstract Underground coal seam mining has been carried out in the Upper Silesian Coal Basin, Poland, for many years and with a simultaneous increase in exploitation depth. Frequently, coal seams are not fully extracted due to numerous reasons which lead to their edges and remnants remaining in the rock mass. Even in the case of the full extraction of a coal seam, mining usually ends at the border of a protecting pillar to protect underground or surface objects, sometimes at the border of the mining area, or some distance from the old goaf or high throw fault. Extraction of subsequent coal seams in an analogous range results in a cluster of coal seam edges remaining. In the vicinity of the mentioned remainders, the disrupted stress distribution is expected. The infraction of the aforementioned equilibrium repeatedly results in the occurrence of strong mining tremors. The observations from the studied coal seam no. 408’s longwall panel indicated that mining works are able to disturb the present stress-strain equilibrium in the area of the edges of other coal seams, even if they are located at a greater vertical distance away. The seismological parameters and distributions have been applied for this purpose.

scholarly journals Overlying Strata Movement and Abutment Pressure Evolution Process of Fully Mechanized Top Coal Caving Mining in Extra Thick Coal Seam

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Yongqiang Zhao ◽  
Yingming Yang ◽  
Xiaobin Li ◽  
Zhiqi Wang
Keyword(s):  
Coal Seam ◽  
Abutment Pressure ◽  
Stress Measurement ◽  
Field Investigation ◽  
Evolution Process ◽  
Thick Coal Seam ◽  
Strata Movement ◽  
Overlying Strata Movement ◽  
Pressure Evolution ◽  
Overlying Strata

Taken overlying strata of fully mechanized top coal caving mining (FMTCCM) in 15 m extra thick coal seam as the research object, the comprehensive research methods such as field investigation, theoretical calculation, and numerical analysis are used to systematically analyze. During the mining of extra thick coal seam, the overlying strata form the structure of lower cantilever beam and upper hinged rock beam. The downward transmission caused by the interaction of this combined structure is the fundamental reason for the strong periodic ground pressure behavior of working face and roadway blow. The movement process of overlying strata movement is divided into four stages, and dynamic distribution characteristics of lateral abutment pressure in different stages are obtained. It is considered that the gob side roadway can be in a relatively stable overburden structure and stress environment during the stable stage of abutment pressure. The distribution range of the internal and external stress fields is determined, which provides a theoretical basis for the reasonable roadway layout. At last, the fracture position and abutment pressure evolution process of overlying strata along the goaf side of the extra thick coal seam are further verified by drilling stress measurement.

Research on Overlying Strata Movement and Deformation under the Conditions of Shortwall and Longwall Mining

2011 ◽  
Vol 90-93 ◽  
pp. 1299-1302 ◽  
Author(s):  
Kuo Li ◽  
Yong Bo Zhang
Keyword(s):  
Coal Mining ◽  
Longwall Mining ◽  
Strata Movement ◽  
Damage Level ◽  
Mining Condition ◽  
Movement And Deformation ◽  
Overlying Strata Movement ◽  
Overlying Strata ◽  
Subsidence Curve

We simulate the rock’s movement and defoemation process in the coal mining, and research the overlying strata movement and deformation under the conditions of shortwall and longwall mining. The conclusion of the experiment indicates: with the method of double deck mining, the rock’s damage level in caving layer is more serious, the final subsidence curve presents a tooth geometry. The subsidence curve of fissure and flexure zone is simily with the longwall mining condition.

Assessment of rigid overlying strata failure in face mining

2010 ◽  
Vol 2 (4) ◽  
Author(s):  
Eva Jiránková
Keyword(s):  
Longwall Mining ◽  
Practical Importance ◽  
Assessment Method ◽  
Coal Seams ◽  
Deep Mine ◽  
Failure Assessment ◽  
Surface Measurements ◽  
Strata Failure ◽  
Simultaneous Assessment ◽  
Overlying Strata

AbstractThe method of overlying strata failure assessment of extracted seams is based upon the simultaneous assessment of surface subsidence and seismic activity, considering the spatiatemporal progress of mining, depending on the character of the rock mass. The rigid overlying strata failure assessment results in finding whether a failure of the firm overlying rocks occurred or whether a strutting arch was formed over the mined-out area. The practical importance of the overlying strata failure assessment consists in determining the size of the mined-out area at which the com-plete failure of the rigid overlying strata occurred and in the assessment of the current stress condition of the overlying strata failure. The assessment method is applicable in deep mine workings where thick coal seams are being mined by means of the method of longwall mining with controlled caving. The results of this method are used to amend contemporary known methods of rock-burst protection, namely (regarding the use of surface measurements for the evaluation) in overlying strata areas.

scholarly journals The Key Stratum Structure Morphology of Longwall Mechanized Top Coal Caving Mining in Extra-Thick Coal Seams: A Typical Case Study

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Fulian He ◽  
Xiaobin Li ◽  
Wenrui He ◽  
Yongqiang Zhao ◽  
Zhuhe Xu ◽  
...  
Keyword(s):  
Coal Seam ◽  
Cantilever Beam ◽  
Coal Seams ◽  
Key Strata ◽  
Key Stratum ◽  
Structure Morphology ◽  
Coal Wall ◽  
Coal Seam Thickness ◽  
Longitudinal Cracks ◽  
Overlying Strata

Longwall mechanized top coal caving mining (LMTCCM) in extra-thick coal seams has its own characteristics. The law of mining pressure and overlying strata failure height in extra-thick coal seams are much larger than those of medium-thick and thick coal seams. The key stratum structure morphology also has an important influence on the law of overlying strata movement and stability of surrounding rock. Based on the engineering geological conditions, this paper used the method of theoretical analysis and numerical simulation to study the key stratum structure morphology of LMTCCM in extra-thick coal seams. The results show that under the condition of LMTCCM in extra-thick coal seams, the key stratum forms the structure of low cantilever beam and high hinged rock beam. With the increase of coal seam thickness, the breaking position of cantilever beam is closer to the coal wall. Through theoretical calculation, it is obtained that the breaking length of cantilever beam is 31.5 m and the breaking position of cantilever beam is 15.4 m away from coal wall. With the increase of cycle, key strata will undergo the evolution law from the generation of longitudinal cracks to the hinged structure and then to the cantilever beam structure. The breakage of key strata will cause the expansion of longitudinal cracks and the overall synchronous movement of overlying strata. With the increase of coal seam thickness, the distribution of longitudinal cracks will gradually transfer from the upper part of goaf to the deep part of coal body in space and increase in quantity. This research is of great significance for improving the stability of overlying strata and ensuring the safe and efficient mining of extra-thick coal seams.

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