scholarly journals The influence of coal and enclosing rock fracturing on the management of the rock massif during the exploitation of thick coal seams by the longwall top coal caving technology

2021 ◽  
Vol 823 (1) ◽  
pp. 012011
Author(s):  
S V Klishin ◽  
G Yu Opruk ◽  
E L Varfolomeev ◽  
I L Borisov
Keyword(s):  
Rock Massif ◽  
Rock Fracturing ◽  
Coal Seams ◽  
Longwall Top Coal Caving

Monitoring and modelling of gas dynamics in multi-level longwall top coal caving of ultra-thick coal seams, Part II: Numerical modelling

2015 ◽  
Vol 144-145 ◽  
pp. 58-70 ◽  
Author(s):  
Guangyao Si ◽  
Ji-Quan Shi ◽  
Sevket Durucan ◽  
Anna Korre ◽  
Jerneja Lazar ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Gas Dynamics ◽  
Coal Seams ◽  
Multi Level ◽  
Longwall Top Coal Caving

scholarly journals MODELING OF STABILITY OF SIDE ROCKS IN A COAL MASIFWITH DIFFERENT METHODS OF SUPPORT THE WORKINGS

2021 ◽  
Vol 37 (3) ◽  
pp. 28-34
Author(s):  
V. Yu. Dovhal
Keyword(s):  
Static Field ◽  
Rock Massif ◽  
Shear Stresses ◽  
Support Structures ◽  
Coal Seams ◽  
Rock Stratum ◽  
Static Loads ◽  
Flexible Support ◽  
Coal Rock ◽  
The Stability

Purpose of work. Determine the conditions of the side rocks stability in a coal massif with different ways of support coal-rock stratum to ensure safe working conditions for miners in the excavation areas of a coal mine with steep coal seams. To achieve this goal, laboratory studies were carried out on models of optical and equivalent materials. The modeling of the stability of side rocks in a coal-rock massif was carried out with the methods of support roadways with vertical timber setsand wooden crib supports: 4-point chock.On models made of optical materials in the analysis of the static field of the distribution of shear stresses in side rocks, the regularity of the change in hazardous manifestations of rock pressure, depending on the deformability of support structures, was recorded. On equivalent models of support structures, the deformation characteristics of experimental samples were determined and their effect on the integrity of the roof under the action of static loads was established. When using rigid support structures in the form of vertical timber sets made of wooden racks to protect sliding drifts, there is a deterioration in the stability of side rocks and destruction of the roof. When using flexible support structures in the form of wooden crib supports: 4-point chock, a smooth deflection of the roof and its integrity are observed. A decrease in the size of the stress concentration zone in the model of a coal-rock massif with workings after the compaction of flexible support structures located above the haul roadway, due to a change in their rigidity, when as a result of the convergence of side rocks, a smooth deflection is provided and the movement of the roof is limited. To ensure the stability of side rocks and development workings, as well as reduce the level of injuries of miners from landslides and collapses in the excavation areas of coal mines that develop steep seams, it is advisable to use flexible support structures, when using which, a smooth deflection of side rocks and their integrity in the mined-out area is ensured coal massif.

scholarly journals Application of BigML in the Classification Evaluation of Top Coal Caving

2021 ◽  
Vol 2021 ◽  
pp. 1-28
Author(s):  
Meng Wang ◽  
Caiwang Tai ◽  
Qiaofeng Zhang ◽  
Zongwei Yang ◽  
Jiazheng Li ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Evaluation Model ◽  
Engineering Practice ◽  
Coal Seams ◽  
Mining Technology ◽  
Evaluation Result ◽  
Sample Data ◽  
Classification Evaluation ◽  
Longwall Top Coal Caving

Longwall top coal caving mining is one of the main methods of mining thick coal seams in China. Therefore, carrying out the classification evaluation of top coal caving is of great significance to ensure mining success and reduce the risk of mining technology. In order to realize the classification evaluation of top coal caving, this article introduces the method of using BigML to establish the classification evaluation model of top coal caving. Furthermore, using the data from the CNKI database as sample data, a classification evaluation model of top coal caving is established on BigML. After training, testing, and optimization, the model is used to evaluate the top coal caving in No. 3 coal seam of Gucheng Coal Mine, and the evaluation result is grade 1, which is consistent with the engineering practice. The final research results show that the application of BigML in the classification evaluation of top coal caving is successful; the evaluation of top coal caving through BigML is reliable; BigML provides another scientific reliability way for the classification evaluation of top coal caving.

scholarly journals Algorithm of rock massif stress-strain state calculation when mining a suite of flat coal seams

2015 ◽  
Vol 9 (1) ◽  
pp. 43-53
Author(s):  
Ya.M Nalyvaiko ◽  
◽  
O.A Akimov ◽  
A.P Diachenko ◽  
A.V Pavlychenko ◽  
...  
Keyword(s):  
Strain State ◽  
Rock Massif ◽  
Coal Seams ◽  
Stress Strain ◽  
Stress Strain State ◽  
State Calculation

scholarly journals Predicting the producing well stability in the place of its curving at the underground coal seams gasification

2019 ◽  
Vol 123 ◽  
pp. 01019 ◽  
Author(s):  
Mykhailo Petlovanyi ◽  
Vasyl Lozynskyi ◽  
Pavlo Saik ◽  
Kateryna Sai
Keyword(s):  
Stress State ◽  
Coal Seam ◽  
Rock Massif ◽  
Curvature Radius ◽  
The Finite Element Method ◽  
Gas Generator ◽  
Coal Seams ◽  
Efficient Operation ◽  
Gas Generators ◽  
The Stability

The relevant issues have been studied of ensuring the stability of producing wells in the place of their curving when uncovering the mining extracted area for the underground gas generator operation. It is emphasized that the design planning of efficient operation of underground gas generators in downhole gasification technology is impossible without consideration of the stress state of the rock massif, which can lead to a danger of the wellbore cutting and emergency shutdown of the technological system operation. The parameters of geomechanical models have been developed and substantiated for the study of the stress state of the “rock massif – producing well” system under the conditions of the Lviv-Volyn coal basin. A computer simulation has been performed of change in the stress state of a laminal massif around a well with a curvature radius in the range of 5 – 25 m with the use of the finite element method. The exponential function has been revealed of the tensile stresses value in the roof of the seam from the angle of the producing well entry into the coal seam. It is recommended the rational angle of a well entry into the coal seam, which is in the range of 21 – 28 degrees, and an appropriate curvature radius will be 5 – 10 m.

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 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 Optimization of Caving Technology in an Extrathick Seam with Longwall Top Coal Caving Mining

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Liu Yang ◽  
Lianghui Li ◽  
Weijie Wei
Keyword(s):  
Body Shape ◽  
Dispersion Coefficient ◽  
Recovery Ratio ◽  
Coal Seams ◽  
Volume Changes ◽  
Positive Order ◽  
New Approach ◽  
Cluster Group ◽  
Single Opening ◽  
Longwall Top Coal Caving

The optimization of top coal caving technology is an efficient method to improve the recovery ratio in longwall top coal caving (LTCC). In extrathick coal seams, the conventional single-opening sequential caving technology (SOSCT) shows the following problems: low recovery ratio, high rock mixed ratio, and poor drawing balance. For these problems, this research verifies the applicability of multiopening caving technology (MOCT) in extrathick coal seams theoretically. However, different drawing sequences have a great effect on the drawing mechanism. Based on the progressive drawing sequence of cluster-group-support, this paper firstly proposes a systematic naming method for the top coal caving technology. Furthermore, an independent cluster-group caving technology (ICGCT) is given, meaning that all supports are divided into several clusters, a cluster is divided into several groups, and clusters extract top coal in positive order while groups are in reverse order in the drawing process. By establishing an experimental model by the discrete element method PFC2D, the drawing mechanism is investigated under different caving technologies. The results show that ICGCT significantly improves the recovery ratio of the panel and mainly increases the drawing volume of top coal in the middle and upper end of the panel. The shape of the top coal boundary reflects the drawing efficiency. Due to the effect of drawing sequence in ICGCT, the generation and disappearance processes of coal ridge greatly decrease the residual top coal in the middle of the panel. The drawing body shape has a direct influence on the recovery ratio. Multiple complete drawing bodies exist in ICGCT, and the dispersion coefficient of drawing volume changes periodically in the range of 0.5–1.7, which is conducive to the management of drawing processes. In addition, discussing ICGCT and the dependent cluster-group caving technology (DCGCT), it is found that the recovery ratio of DCGCT has a slight increase, which enlarges the maximum drawing range of top coal at both panel ends, shortening the total drawing time of the panel. In summary, ICGCT provides a new approach for improving the recovery ratio and drawing balance in LTCC with an extrathick coal seam.

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