scholarly journals Analysis of the Geomechanical Phenomena that Led to the Appearance of Sinkholes at the Lupeni Mine, Romania, in the Conditions of Thick Coal Seams Mining with Longwall Top Coal Caving

2021 ◽  
Vol 13 (11) ◽  
pp. 6449
Author(s):  
Dacian-Paul Marian ◽  
Ilie Onica
Keyword(s):  
Laser Scanning ◽  
Ground Surface ◽  
Coal Seams ◽  
Coal Basin ◽  
Thick Coal Seam ◽  
Aerial Laser Scanning ◽  
Mining Depth ◽  
Mining Conditions ◽  
Elasto Plasticity ◽  
Longwall Top Coal Caving

Thick coal seam no. 3, block V, Lupeni mine was mined by longwall top coal caving (LTCC). After the coal mining, the ground surface underwent continuous subsidence, but since 2008, three sinkholes have appeared on the surface with important dimensions, atypical for the geo-mining conditions in this coal basin. This article is a synthesis of the study meant to decipher the geo-mechanical phenomenon that led to the emergence of these sinkholes and highlighting the main factors that contributed to the development of this phenomenon. For this purpose, measurements were made on the terrain deformations using photogrammetric methods and aerial laser scanning, when modeling with 3D finite elements, in elasto-plasticity and with the help of the Knothe–Budrik influence function. The factors that contributed to the occurrence of discontinuous subsidence phenomena are shallow mining depth, the LTCC mining method, and the presence of faults in the vicinity of the mining panels. Additionally, the geo-mechanical phenomena of subsidence terrace development and sinkholes in the mining subsidence troughs at the Lupeni mine were described.

scholarly journals Methane emissions against the background of natural and mining conditions in the Budryk and Pniówek mines in the Upper Silesian Coal Basin (Poland)

2021 ◽  
Vol 80 (22) ◽  
Author(s):  
Marcin Dreger ◽  
Sławomir Kędzior
Keyword(s):  
Methane Emissions ◽  
Geological Structure ◽  
Methane Content ◽  
Coal Extraction ◽  
Hard Coal ◽  
Coal Seams ◽  
Coal Basin ◽  
Related Factors ◽  
Upper Silesian Coal Basin ◽  
Mining Conditions

AbstractThe paper presents the variability of hard coal output, methane content and methane emissions into coal workings and into the atmosphere from the two most methane-gassy coal mines in Poland. The Budryk mine is one of the youngest mines in Poland, but it is the most methane-gassy as well. In 2016, the total CH4 emissions exceed 140 million of m3. This large increase in methane emissions to mine workings is primarily related to the increase in the depth of coal extraction (up to 1290 m) and, consequently, the rapid increase in the methane content in coal seams (up to 10–12 m3/Mg coaldaf). On the other hand, in the Pniówek mine, methane emission was the highest at the beginning of the study period (1986–1991). During the following years, emission decreased to the values of less than 140 million of m3, which were still one of the largest amounts of emitted methane in the entire Upper Silesian Coal Basin. The coexistence of natural factors, such as the geological structure and gas distribution, as well as mining-related factors, i.e. the depth of mining, the intensity of coal extraction determines the temporal variability of methane emissions in the studied mines.

Study on Overburden Strata Rupture Development Height Rules in Repeated Mining of Thick Coal Seams

2012 ◽  
Vol 170-173 ◽  
pp. 279-282
Author(s):  
Nan Nan Zhao ◽  
Yong Jie Yang ◽  
Chang Qing Wang
Keyword(s):  
Coal Seam ◽  
Field Measurement ◽  
Development Time ◽  
Lower Layer ◽  
Coal Seams ◽  
Thick Coal Seam ◽  
Upper Limit ◽  
Mining Conditions ◽  
Overburden Strata

Take 3 coal repeated mining of Luxi colliery as research background, overburden strata rupture development rules in repeated mining of thick coal seam were studied by using the methods of field measurement. The results indicate that the height of overburden crack belt reduced along with the increase of goaf development time; the crack belt height of upper layer is 34.73m, the ratio of crack height and mining thickness is 15.1, the crack belt height of lower layer increased to 41.51m, but the increased trend declined, the ratio is only 12.14, the development height after up-layer was excavated is 83.6% of the height after two coalface were excavated. The results have important guiding sense for predicting overburden rupture rules in the similar mining conditions and improving the upper limit.

Ground surface subsidence as effect of underground mining of the thick coal seams in the Jiu valley basin / Osiadanie gruntów wskutek wybierania pokładów o dużej miąższości w kopalniach zagłębia w dolinie Jiu

2012 ◽  
Vol 57 (3) ◽  
pp. 547-577 ◽  
Author(s):  
Ilie Onica ◽  
Dacian Marian
Keyword(s):  
Surface Deformation ◽  
Longwall Mining ◽  
Underground Mining ◽  
Ground Surface ◽  
Surface Subsidence ◽  
Coal Seams ◽  
Elasto Plasticity ◽  
Ground Surface Subsidence ◽  
Time Dependent Analysis

Abstract In the case of the thick and gentle coal seam no. 3 of the Jiu Valley Coal Basin (Romania), the mining methods are by use of the longwall mining technologies with roof control by caving or top coal caving. In this paper, it is presented the analysis of the complex deformations of the ground surface, over time, as a consequence of the coal mining in certain mining fields of the basin. Also, it is analysed the ground surface subsidence phenomenon using the CESAR-LCPC finite element code. The modelling is made in the elasticity and the elasto-plasticity behaviour hypothesis. Also, the time dependent analysis of the ground surface deformation was achieved with the aid of an especial profile function. The obtained results are compared with the in situ measurements data basis.

scholarly journals Experimental Studies about Characteristics of the Rocks Displacement and State of Bearing Pressure on the Haulage Roadway

2019 ◽  
Vol 105 ◽  
pp. 01008
Author(s):  
Duc Thang Pham ◽  
Hung Thang Hoang ◽  
Victor Vitcalov
Keyword(s):  
Rock Pressure ◽  
Roof Rock ◽  
Experimental Studies ◽  
Coal Seams ◽  
Coal Basin ◽  
Mining Depth ◽  
The Face ◽  
Mine Workings ◽  
Roof Rocks ◽  
Quang Ninh

Comprehensive studies were conducted using measuring stations to measure the rock pressure and displacements of the roof rocks in the mine workings adjacent to the face when extracting medium thick inclined coal seams with the use of longwall (seam 6 at the Quang Hanh mine of Quang Ninh coal basin, Vietnam). The results of the study show that the displacement of the roof rock on the parallel roadway increases sharply at a distance of 1 to 12 m to the face, varies from 20 to 40 mm when the mining depth of the coal seam is 200 m and the maximum rock pressure on the haulage roadway supports is located at a distance of 3–8 m ahead of the face and is from 14 to 16 tons ranges.

The application of high‐resolution seismics in Polish coal mining

Geophysics ◽  
1992 ◽  
Vol 57 (1) ◽  
pp. 171-180 ◽  
Author(s):  
Kaja Pietsch ◽  
Ryszard Ślusarczyk
Keyword(s):  
High Resolution ◽  
Coal Mining ◽  
Seismic Wave ◽  
Theoretical Modeling ◽  
Coal Seams ◽  
Coal Basin ◽  
Seismic Surveys ◽  
Coal Deposits ◽  
Mining Conditions ◽  
Geological Models

Use of high‐resolution seismics were applied to the exploration and development of coal deposits in the Upper Silesian and the Lublin Coal Basins in Poland. High‐resolution seismic surveys were carried out in various geological and mining conditions. The objectives were to map commercial coal seams, locate coal‐less zones and faults, and solve some problems associated with mining conditions, e.g., determining the height of caving roof zone. Theoretical modeling studies of seismic wave response for several geological models representing the coal‐basin structures were used to address these problems. Results from these successful surveys helped improved designs of new mines and/or expand existing ones to provide more productive and safer coal mines.

scholarly journals Study on Controlling Parameters and Technological Optimization of Strip Longwall Top Coal Caving in Thick Coal Seams

2020 ◽  
Vol 1 (2) ◽  
Author(s):  
Bui MANH TUNG ◽  
Le TIEN DUNG ◽  
Liu CHANG YOU ◽  
Pham VAN CHUNG
Keyword(s):  
Recovery Rate ◽  
Technological Parameters ◽  
Coal Seams ◽  
Efficient Operation ◽  
Coal Recovery ◽  
Mining Conditions ◽  
Face Length ◽  
Longwall Top Coal Caving ◽  
Cutting Height ◽  
Selection Of

Based on the geological and mining conditions of face 3107 at Liang Baoshi coal mine, China, the numerical programs FLAC3D 2.10 and PFC2D 2.10 were used to analyze the parameters controlling the failure, caving and the coal recovery rate in Strip Longwall Top Coal Caving (SLTCC). The analyzed parameters are face length in dip direction, mining height, the span of coal caving, and sequence of coal drawing. The results show that the application of SLTCC for a limited face length is not favourable to coal failure, and it increases top coal loss. A sound engineering selection of technological parameters is therefore important to efficient mining in thick coal seams. The numerical results show that a face design of 3 m of cutting height, 0.8 m of caving span, and alternate drawing sequence results in high coal recovery rate, simple mining tasks, and efficient operation of face equipment.

scholarly journals Cooperative Control Mechanism of Long Flexible Bolts and Blasting Pressure Relief in Hard Roof Roadways of Extra-Thick Coal Seams: A Case Study

2021 ◽  
Vol 11 (9) ◽  
pp. 4125
Author(s):  
Zhe Xiang ◽  
Nong Zhang ◽  
Zhengzheng Xie ◽  
Feng Guo ◽  
Chenghao Zhang
Keyword(s):  
Coal Seam ◽  
Cooperative Control ◽  
Field Tests ◽  
Surrounding Rock ◽  
Deep Hole ◽  
Coal Seams ◽  
Thick Coal Seam ◽  
Structure Damage ◽  
Hard Roof

The higher strength of a hard roof leads to higher coal pressure during coal mining, especially under extra-thick coal seam conditions. This study addresses the hard roof control problem for extra-thick coal seams using the air return roadway 4106 (AR 4106) of the Wenjiapo Coal Mine as a case study. A new surrounding rock control strategy is proposed, which mainly includes 44 m deep-hole pre-splitting blasting for stress releasing and flexible 4-m-long bolt for roof supporting. Based on the new support scheme, field tests were performed. The results show that roadway support failure in traditional scenarios is caused by insufficient bolt length and extensive rotary subsidence of the long cantilever beam of the hard roof. In the new proposed scheme, flexible 4-m-long bolts are shown to effectively restrain the initial expansion deformation of the top coal. The deflection of the rock beam anchored by the roof foundation are improved. Deep-hole pre-splitting blasting effectively reduces the cantilever distance of the “block B” of the voussoir beam structure. The stress environment of the roadway surrounding rock is optimized and anchorage structure damage is inhibited. The results provide insights regarding the safe control of roadway roofs under extra-thick coal seam conditions.

Volcanoclastic minerals of some Czechoslovakian tonsteins and their alteration

Clay Minerals ◽  
1992 ◽  
Vol 27 (3) ◽  
pp. 269-282 ◽  
Author(s):  
Z. Weiss ◽  
A. Baronnet ◽  
M. Chmielova
Keyword(s):  
Coal Seams ◽  
Coal Basin ◽  
Upper Carboniferous ◽  
Upper Silesian Coal Basin ◽  
Mineral Assemblages ◽  
Clayey Rocks ◽  
Quartz Grains

AbstractIn the Czechoslovak part of the Upper Silesian Coal Basin (Ostrava-Karvina Coal Basin), only part of the Upper Carboniferous (Namurian A, B, C and Westphalian A) is well developed, and tonsteins, which are clayey rocks or claystones, occur as thin, clayey interlayers in the coal seams. Two types of primary volcanic mineral assemblages were identified in four tonstein samples from different coal seams; the first type is characterized by the presence of biotite and sanidine, and the second by the presence of biotite, bytownite and Ca-amphibole. All tonsteins studied contained kaolinite minerals, volcanic quartz grains, crystals of zircon and apatite. Separated biotite flakes with an admixture of kaolinite layers were identified as 1M polytype. The flakes without kaolinite minerals were identified as epitactic overgrowth of 1M and complex polytypes, and twinned crystals of 2M1 polytype. Kaolinization of biotite flakes was observed in all tonstein samples studied. Kaolinite single layers (7 Å) as well as two-layer polytype of kaolinite minerals (14 Å) sandwiched between biotite layers (10 Å) were identified by HRTEM imaging.

scholarly journals Augmentation of Traditional Forest Inventory and Airborne Laser Scanning with Unmanned Aerial Systems and Photogrammetry for Forest Monitoring

2018 ◽  
Vol 10 (10) ◽  
pp. 1562 ◽  
Author(s):  
Kathryn Fankhauser ◽  
Nikolay Strigul ◽  
Demetrios Gatziolis
Keyword(s):  
Laser Scanning ◽  
Canopy Cover ◽  
Tree Height ◽  
Forest Monitoring ◽  
Unmanned Aerial Systems ◽  
Aerial Laser Scanning ◽  
Forest Inventories ◽  
Airborne Laser ◽  
Aerial Systems

Forest inventories are constrained by resource-intensive fieldwork, while unmanned aerial systems (UASs) offer rapid, reliable, and replicable data collection and processing. This research leverages advancements in photogrammetry and market sensors and platforms to incorporate a UAS-based approach into existing forestry monitoring schemes. Digital imagery from a UAS was collected, photogrammetrically processed, and compared to in situ and aerial laser scanning (ALS)-derived plot tree counts and heights on a subsample of national forest plots in Oregon. UAS- and ALS-estimated tree counts agreed with each other (r2 = 0.96) and with field data (ALS r2 = 0.93, UAS r2 = 0.84). UAS photogrammetry also reasonably approximated mean plot tree height achieved by the field inventory (r2 = 0.82, RMSE = 2.92 m) and by ALS (r2 = 0.97, RMSE = 1.04 m). The use of both nadir-oriented and oblique UAS imagery as well as the availability of ALS-derived terrain descriptions likely sustain a robust performance of our approach across classes of canopy cover and tree height. It is possible to draw similar conclusions from any of the methods, suggesting that the efficient and responsive UAS method can enhance field measurement and ALS in longitudinal inventories. Additionally, advancing UAS technology and photogrammetry allows diverse users access to forest data and integrates updated methodologies with traditional forest monitoring.

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