Research on the Underground Pressure Behavior Law of Repeated Mining Working Face under the Gob of Small Colliery

2014 ◽  
Vol 522-524 ◽  
pp. 1434-1440
Author(s):  
Chun Xiang Hu ◽  
Jin Kai Liu ◽  
Qi Li ◽  
Yong Zhang
Keyword(s):  
Lower Layer ◽  
Measurement Data ◽  
Simulation Software ◽  
Efficient Production ◽  
Distribution Law ◽  
Pressure Behavior ◽  
Safe Production ◽  
Working Face ◽  
Practical Engineering ◽  
Residual Coal

The gob of small colliery has been one of the main factors threatening the safe production of coal mine. The repeated mining working face in a certain mine is the practical engineering background in this paper to study the influence of gob in small colliery on the mining of lower layer. By using the numerical simulation software FLAC3D, the stress distribution law and the change of displacement during lower layer mining were analysed. It can be concluded from the analysis of field measurement data that: there is stress relief under the gob of small colliery because the distribution of coal is irregular resulting from the random distribution of gobs in small colliery, while the residual coal causes the effect of stress concentration on the lower layer mining; relatively large displacement appears in the caving zone of the upper layer by the roof of working face and the support should be strengthened appropriately during mining; meanwhile, the gob of small colliery can cause the nonuniform distance of periodic weighting in the roof, and segmented pressure behavior can be observed during the periodic weighting of the working face. Research results could provide some guidance to the safe and efficient production in repeated mining working face in the mining with similar conditions.

scholarly journals The Influences of Key Strata Compound Breakage on the Overlying Strata Movement and Strata Pressure Behavior in Fully Mechanized Caving Mining of Shallow and Extremely Thick Seams: A Case Study

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Junmeng Li ◽  
Yanli Huang ◽  
Jixiong Zhang ◽  
Meng Li ◽  
Ming Qiao ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Abutment Pressure ◽  
Simulation Software ◽  
Strata Movement ◽  
Key Strata ◽  
Pressure Behavior ◽  
Ground Pressure ◽  
Working Face ◽  
Overlying Strata Movement ◽  
Overlying Strata

In order to analyze the impact of compound breakage of key strata on overlying strata movement and strata pressure behavior during the fully mechanized caving mining in shallow and extremely thick seams, this paper took the 1322 fully mechanized caving face in Jindi Coal Mine in Xing County as the engineering background. Under the special mining and geological condition mentioned above, UDEC numerical simulation software was applied to research the engineering problems, and results of numerical simulation were verified through the in-site measurement. The research results showed that during the fully mechanized caving mining in shallow and extremely thick seams, the inferior key strata affected by mining movement behaved in the mode of sliding instability and could not form the stable structure of the voussoir beam after breaking and caving. In addition, the main key strata behaved in the mode of rotary instability, and the caving rocks behind the goaf were gradually compacted because of the periodic instability of the main key strata. With the continuous advance of the working face, the abutment pressure of the working face was affected by the compound breakage and periodic instability of both the inferior key strata and the main key strata, and the peaks of the abutment pressure presented small-big-small-big periodical change characteristics. Meanwhile, the risk of rib spalling ahead of the working face presented different levels of acute or slowing trends. The actual measurement results of ground pressure in the working face showed that, in the working process, the first weighting interval of the inferior key strata was about 51 m and its average periodic weighting interval was about 12.6 m, both of which were basically consistent with the results of numerical simulation. The research has great significance in providing theoretical guidance and practical experience for predicting and controlling the ground pressure under the similar mining and geological conditions.

scholarly journals A protective seam mining method by cutting roof with chainsaw arm machine

2020 ◽  
Author(s):  
Tiejun Kuang ◽  
Yang Tai ◽  
Bingjie Huo ◽  
Binwei Xia ◽  
Yanqun Zhang ◽  
...  
Keyword(s):  
Lower Layer ◽  
Mining Method ◽  
Coal Seams ◽  
Working Face ◽  
Protective Seam ◽  
Mining Pressure ◽  
Coal Pillars ◽  
Residual Coal ◽  
Seam Mining ◽  
Protective Seam Mining

Abstract Multiple-layered coal seams widely exist in main coal mining areas of China. When these coal seams are exploited, the pillar mining method is always employed. This leads to many coal pillars left in the upper coal seams as a protective barrier. As a result, these residual pillars will not only cause the loss of coal resources but also could trigger environmental issues and a serious of mine disasters. A theoretical model was built to analyse the effect of the residual pillars. From the theoretical model, it was found that four stress concentration areas were formed by the upper residual coal pillars. To address the issues of the residual coal pillars, Datong Coal Mine Group has developed an innovative technology of the roof cutting with a chainsaw. A new protective coal seam mining method using chainsaw roof-cutting technology is introduced. A numerical model is constructed to analyse the mining pressure distribution law in working face within the lower layer coal seam. From the numerical simulation, the new protective layer mining method could reduce about 15.2% of the advancing stress, which contributes a lot to controlling the mining pressure within the lower layer. The field measurement showed that the hydraulic support utilised at the site was at lower pressure levels, which proves the new protective seam mining method can significantly reduce the working face pressure.

scholarly journals A numerical simulation of realistic top coal caving intervals under different top coal thicknesses in longwall top coal caving working face

2021 ◽  
Author(s):  
Chuang Liu ◽  
Huamin Li
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Distinct Element ◽  
Simulation Models ◽  
Simulation Software ◽  
Thick Coal Seam ◽  
Coal Recovery ◽  
Working Face ◽  
Longwall Top Coal Caving ◽  
Selection Of

Abstract In the process of longwall top coal caving, the selection of the top coal caving interval along the advancing direction of the working face has an important effect on the top coal recovery. To explore a realistic top coal caving interval of the longwall top coal caving working face, longwall top coal caving panel 8202 in the Tongxin Coal Mine is used as an example, and 30 numerical simulation models are established by using Continuum-based Distinct Element Method (CDEM) simulation software to study the top coal recovery with 4.0 m, 8.0 m, 12.0 m, 16.0 m, 20.0 m and 24.0 m top coal thicknesses and 0.8 m, 1.0 m, 1.2 m, 1.6 m and 2.4 m top coal caving intervals. The results show that with an increase in the top coal caving interval, the single top coal caving amount increases. The top coal recovery is the highest with a 0.8 m top coal caving interval when the thickness of the top coal is less than 4.0 m, and it is the highest with a 1.2 m top coal caving interval when the coal seam thickness is greater than 4.0 m. These results provide a reference for the selection of a realistic top coal caving interval in thick coal seam caving mining.

scholarly journals Safe and Efficient Coal Mining Below the Goaf: A Case Study

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 864 ◽  
Author(s):  
Weidong Pan ◽  
Shaopeng Zhang ◽  
Yi Liu
Keyword(s):  
Abutment Pressure ◽  
Theoretical Calculations ◽  
Distribution Law ◽  
Working Face ◽  
Strata Behavior ◽  
Working Resistance ◽  
Behavior Characteristics ◽  
Theoretical Analyses ◽  
Important Significance

Mining at the fully mechanized working face below the goaf of the short-distance coal seam is influenced by the upper goaf. To address this problem, methods such as theoretical analyses, numerical simulation, and on-site measurement are used to study the strata behavior characteristics of the Ningxia Lingxin Coal Mine 051508 working face in this study. The roof weighting intervals of the working faces below the goaf and the non-goaf are obtained via theoretical calculations. The stoping processes of the working faces below the goaf and the non-goaf are simulated with FLAC3D to obtain the distribution law of the bearing pressure and plastic zones before the working face. Based on the statistical analysis of the measured working resistance of the supports and its distribution, the roof weighting interval of the working face mining below the goaf is obtained. The results show that the roof weighting interval and the advanced abutment pressure during mining at the working face below the goaf are smaller than those below the non-goaf, providing a reasonable theoretical basis for mining below the goaf, and having important significance for safe and efficient mining.

scholarly journals Research on the Source Mechanism and Source Prevention and Control System of Deep Rock Burst

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Shuai Di
Keyword(s):  
Control System ◽  
Rock Mass ◽  
Rock Burst ◽  
Prevention And Control ◽  
Economic Benefits ◽  
Efficient Production ◽  
Targeted Prevention ◽  
Working Face ◽  
Deep Rock ◽  
And Control

Deep rock burst accidents occur frequently and become increasingly serious. Further improving the effectiveness and accuracy of the prevention and control of rock burst, ensuring the safe and efficient production of mines, clarifying the basic causes of disasters, and refining the type of deep rock burst are the most important key links. Aiming at the problems such as unclear incentives and types and the lack of effective and targeted prevention measures of deep rock burst, taking Xin’an Mine as the research background, based on the energy theory, the coal and rock mass multisource energy unified equation was established to analyze coal and rock mass instability mechanism. According to the different degrees of participation of various factors, the types of deep rock burst are determined as three categories and four types, and the corresponding judgment criteria are proposed. The precise prevention and control system for the source of rock burst with Xin’an characteristics is proposed, successfully applied to the 8101 working face, which not only guarantees the safe production of the working face, but also achieves good economic benefits. The research results lay the foundation for improving the accuracy and precision of the prevention and control of deep rock burst and provide theoretical guidance for the safe and efficient mining of the mine.

scholarly journals Study on Flow Field and Rotor Safety Characteristics of MSPs Based on Flow Thermo-Coupling

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 711
Author(s):  
Yiming Chen ◽  
Rongsheng Zhu ◽  
Yonggang Lu ◽  
Zhenjun Gao ◽  
Junjun Kang
Keyword(s):  
High Temperature ◽  
Equivalent Stress ◽  
Outer Edge ◽  
Cover Plate ◽  
Distribution Law ◽  
Maximum Deformation ◽  
Structural Intensity ◽  
Operation Conditions ◽  
Working Face ◽  
Different Temperatures

In order to obtain the structural intensity under the operation conditions of MSP (molten salt pump), the rotor component of MSP is taken as the research object. In this paper, the influence of material properties change on the structural performance of MSP at different temperatures is analyzed. The stress distribution and strain distribution of MSP rotor components under different loads are investigated, and the intensity calculation of MSP rotor system is carried out to explore whether it meets the intensity requirements under high temperature operation, which lays a foundation for the high temperature test of MSP. The results show that the maximum deformation position of the blade working face appears at the outer edge of the impeller. When the fluid-structure coupling is applied, the blade strain law and the strain law during thermo-coupling are similar. The effect of the temperature field on the degree of blade deformation is not significant, provided that other factors remain the same. The position where the impeller equivalent stress is the largest is mainly concentrated in the area where the blade is in contact with the front and rear cover plates at the outlet of the impeller. Different degrees of stress concentration occur in the area where the blade is in contact with the impeller hub. The distribution law of the equivalent stress on the surface of the impeller cover plate is that the equivalent stress value changes periodically along the circumferential direction of the impeller, and the number of change cycles is equal to the number of impeller blades. This study can provide a reference for the structural design of MSPs.

scholarly journals Multibody dynamic modelling of a direct wind turbine drive train

2019 ◽  
Vol 44 (5) ◽  
pp. 519-547
Author(s):  
Saeed Asadi ◽  
Håkan Johansson
Keyword(s):  
Wind Turbine ◽  
Measurement Data ◽  
Dynamic Modelling ◽  
Simulation Software ◽  
Operating Conditions ◽  
Drive Train ◽  
Operational Experience ◽  
Main Bearing ◽  
Wide Range ◽  
Turbine Drive

Wind turbines normally have a long operational lifetime and experience a wide range of operating conditions. A representative set of these conditions is considered as part of a design process, as codified in standards. However, operational experience shows that failures occur more frequently than expected, the costlier of these including failures in the main bearings and gearbox. As modern turbines are equipped with sophisticated online systems, an important task is to evaluate the drive train dynamics from online measurement data. In particular, internal forces leading to fatigue can only be determined indirectly from other locations’ sensors. In this contribution, a direct wind turbine drive train is modelled using the floating frame of reference formulation for a flexible multibody dynamics system. The purpose is to evaluate drive train response based on blade root forces and bedplate motions. The dynamic response is evaluated in terms of main shaft deformation and main bearing forces under different wind conditions. The model was found to correspond well to a commercial wind turbine system simulation software (ViDyn).

Image Reconstruction Algorithm Based On PCA and WNN for ECT

2013 ◽  
Vol 5 (4) ◽  
pp. 33-40
Author(s):  
Lifeng Zhang
Keyword(s):  
Image Reconstruction ◽  
Adaptive Learning ◽  
Transfer Functions ◽  
Measurement Data ◽  
Principal Component ◽  
Reconstruction Algorithm ◽  
Simulation Software ◽  
Iteration Algorithm ◽  
Two Phase ◽  
Image Reconstruction Algorithm

Electrical capacitance tomography (ECT) technique is a new technique for two-phase flow measurement. ECT is a complex nonlinear problem. To solve the ill-posed image reconstruction problem, image reconstruction algorithm based on wavelet neural networks (WNN) was presented. The principal component analysis (PCA) method was used to reduce the dimension of the input vectors. The transfer functions of the neurons in the WNN were wavelet base functions which were determined by retract and translation factors. The input measurement data were obtained using the ECT simulation software developed by the author. BP algorithm was used to train the WNN, and self-adaptive learning rate and momentum coefficient were also used to accelerate the learning speed. Experimental results showed the image quality has been improved markedly, compared with the typical linear back projection (LBP) algorithm and Landweber iteration algorithm.

Optimal Design of Working Face Ventilating System of Huoerxinhe Company

2014 ◽  
Vol 998-999 ◽  
pp. 446-449
Author(s):  
Li Ping Yang ◽  
Wei Qiao ◽  
Hou Quan Zhou
Keyword(s):  
Optimal Design ◽  
Coal Mine ◽  
Efficient Production ◽  
Ventilation Mode ◽  
Working Face ◽  
Mode 2 ◽  
Waste Air ◽  
Type Mode ◽  
Coal Pillars ◽  
Tunneling Engineering

In order to guarantee the safe and efficient production of coal mine of Huoerxinhe Company, for the problems of gas exceeding limitation, excavating replacement tension, resource waste air leaking and so on, the ventilation mode was optimized and Y type ventilation mode was adopted. Practices indicate that this ventilation mode is entirely feasible on working face of Huoerxinhe Company. Through this mode, we can (1) decrease the tunneling engineering quantity, improve the excavating replacement tension of double U type mode; (2) reduce the protective coal pillars to cut down resource waste; (3) solve the problem of gas exceeding limitation on upper corner thoroughly.

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