scholarly journals Deformation Law and Control Measures of Gob-Side Entry Filled with Gangue in Deep Gobs: A Case Study

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Xun Liu ◽  
Shihao Tu ◽  
Dingyi Hao ◽  
Yida Lu ◽  
Kaijun Miao ◽  
...  
Keyword(s):  
Coal Pillar ◽  
Stress Transfer ◽  
Control Measures ◽  
Theoretical Derivation ◽  
Simulation Research ◽  
Deformation Control ◽  
Deformation Problem ◽  
Working Face ◽  
Large Deformation Problem ◽  
Application Requirements

Aiming at the large deformation problem of gob-side entry in solid filling mining, the roof subsidence of gob-side entry retaining (GER) was studied under the influence of gangue filling, by taking a deep filling working face in Shandong Province as the engineering background and using theoretical derivation as well as FLAC3D numerical simulation. Research shows that the stiffness of the gangue filling body in the gob and the stiffness and width of the entry protection coal and rock mass (EPCARM) are positively correlated with the GER roof subsidence, which is much less affected by the EPCARM parameters than by the GER stiffness. The GER failure to meet the application requirements is mainly attributed to the insufficient stiffness of the gangue filling body and excessive advance subsidence, which inhibit the roof stress transfer. The GER replacement by the gob-side entry driving (GED) scheme, which implies replacing the entry protection gangue bag wall with the coal pillar with a width of 5 m, will reduce the roof subsidence to 0.114 m, according to the proposed equation. The results obtained are considered quite instrumental in deformation control of the gob-side entry filled with gangue, as well as substantiation of GED and GER applicability options.

scholarly journals Simulation Analysis and Engineering Application of Retaining Width of Waterproof Coal Pillar in Island Working Face

2021 ◽  
Author(s):  
Lili Zheng ◽  
Zheng Gao
Keyword(s):  
Service Life ◽  
Simulation Analysis ◽  
Engineering Application ◽  
Coal Pillar ◽  
Surrounding Rock ◽  
Simulation Research ◽  
Working Face ◽  
Before And After ◽  
Mining Face ◽  
Coal Pillars

The old mining area in Pingdingshan coalfield has the following problems: long mining service life, many remaining coal pillars, and great difficulty in mining; to extend the service life of the mine, realize cost saving and efficiency increasing, it is urgent to recover the remaining coal pillars, but the mining of isolated island face faces the problem of reasonable retention of waterproof coal pillars, if the protection is not good, it is easy to cause mine water damage and increase the mining cost. Therefore, in view of the practical engineering problems faced by the field, aiming at eliminating or reducing the goaf water disaster, this paper adopts numerical simulation research methods to optimize the original design scheme and carry out comparative analysis, dynamically reappear the surrounding rock stress field, displacement field and plastic failure law under multi face mining and roadway mining, and carry out engineering practice application. The results show that there is a certain thickness of elastic core area before and after mining with 25m coal pillar width. The deformation of surrounding rock is small, which is conducive to roadway maintenance, without obvious stress concentration. It can meet the actual needs of the project. The mining face has achieved safe mining, without water inrush accident in the goaf, and the coal resources have been recovered to the maximum extent. The research results are left over to similar mining areas in China The safe recovery of coal pillar can be used for reference.

scholarly journals Layout of the First-Mining Working Face in the Protected Seam for Pressure Relief by Peak Stress Shift

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xiao-Xu Gao ◽  
Guo-Jin Chai ◽  
Guang-An Zhu
Keyword(s):  
Evaluation Method ◽  
Coal Pillar ◽  
Stress Transfer ◽  
Peak Stress ◽  
Infinite Plane ◽  
Horizontal Distance ◽  
Analytic Hierarchy ◽  
Working Face ◽  
Weighted Values ◽  
Hierarchy Process

An appropriate layout of the first-mining working face of protected seams is key to rockburst prevention in coal seams. By taking the first-mining working face in the 2-2# middle coal seam in Hulusu Coal Mine as the background, a mechanical model for the stress distribution after mining the upper protective seams was established through theoretical analysis and in situ measurement. The problem concerning the layout of the first-mining working face in the protected seam was transformed into one concerning the optimal horizontal distance L. Furthermore, based on the theory of stress transfer within a semi-infinite plane, the distribution of the vertical stress in the protected seam was deduced, for which numerical simulation was performed. Through calculation, it is best (in terms of roadway excavation) to set L to between 50 and 75 m; the mining-induced disturbance shows the least influence on the two roadways at L = 80 to 140 m and at L = 40 to 100 m, and the influence of the remaining coal pillar on mining of the working face is the least significant. Based on the analytic hierarchy process (AHP) evaluation method, the weights of three groups of contradictory criteria and the weighted values of the peak stress under different values of L were calculated. The results show that the global stress on the first-mining working face in the protected seams is lowest at L = 60 m. The results can provide a reference for the layout of the working faces in protected seams in adjacent coal mines.

Study on the Response of Surrounding Rock for Gob-Side Entry Retaining under the Mining

2013 ◽  
Vol 448-453 ◽  
pp. 3879-3883 ◽  
Author(s):  
Mao Sen Zhao ◽  
Ke Min Wei ◽  
Ze Kang Wen ◽  
You Ling Fang
Keyword(s):  
Coal Mining ◽  
Shear Failure ◽  
Horizontal Displacement ◽  
Mechanical Analysis ◽  
Surrounding Rock ◽  
Analysis Model ◽  
Maximum Displacement ◽  
Deformation Problem ◽  
Working Face ◽  
Large Deformation Problem

A coal mine in Chongqing +590m south four district 2443 working face as the research object, using the finite difference method (FLAC) which can solve the nonlinear large deformation problem, setting up the mechanical analysis model of the gob-side entry retaining, analyzing the structure characteristics of surrounding rock, and studying on the stability of surrounding rock of the gob-side entry retaining under the mining. the results showed that:(1) After the coal mining, the maximum displacement of roof has occurred on the edge of the roadway upper side near the filling body. The floor heave at the beginning mining, the floor has a downward displacement after the mining;(2)After the coal mining, the surrounding rock of the gob-side entry retaining has a larger range of shear failure, a strong tensile damage was occurred in filling body, big horizontal displacement was happened in the middle of filling body. Research results can provide reference for similar coal mining..

Stress Evolution and Deformation Control Technology for Deep Mining Influenced Roadway

2011 ◽  
Vol 90-93 ◽  
pp. 137-145
Author(s):  
Jia Guang Kan ◽  
Nong Zhang ◽  
Hai Wei Zhang ◽  
Zhi Yi Zhang ◽  
Guang Yao Si
Keyword(s):  
Coal Pillar ◽  
Surface Displacement ◽  
Mining Area ◽  
Surrounding Rock ◽  
Stress Evolution ◽  
Deformation Control ◽  
Working Face ◽  
Geological Conditions ◽  
Basic Ideas ◽  
Roadway Deformation

In order to effectively control deep roadway under mining influence, based on the typical engineering geological conditions of Dingji coalmine in Huainan mining area, we researched on the laws of stress evolution and failure mechanism of roadway influenced by working face advancing by using numerical simulation and applying field test. The results showed that the surrounding rock stress of roadway ribs increased gradually with face advancing, vertical stress peak transfer to in-depth of roadway surrounding rock, the trend of roadway surface displacement variation consistent with corresponding stress variation. An appropriate coal pillar size (105 m) was proposed. We put forward the basic ideas for surrounding rock controlling and surrounding rock reinforce technology, namely U-steel support back grouting and bolt-cable cooperative supporting. By roadway deformation, roof layer separation and borehole detecting, we found out that displacement of roadway ribs was less than 250 mm, subsidence of roof was less than 110 mm, and the roadway deformation has been effectively controlled.

scholarly journals Comprehensive technical support for safe mining in ultra-close coal seams: A case study

2021 ◽  
pp. 014459872110093
Author(s):  
Wei Zhang ◽  
Jiawei Guo ◽  
Kaidi Xie ◽  
Jinming Wang ◽  
Liang Chen ◽  
...  
Keyword(s):  
Coal Seam ◽  
Technical Support ◽  
Surrounding Rock ◽  
Coal Seams ◽  
Deformation Control ◽  
Hard Roof ◽  
Working Face ◽  
Close Coal Seams ◽  
Safe Mining

In order to mine the coal seam under super-thick hard roof, improve the utilization rate of resources and prolong the remaining service life of the mine, a case study of the Gaozhuang Coal Mine in the Zaozhuang Mining Area has been performed in this paper. Based on the specific mining geological conditions of ultra-close coal seams (#3up and #3low coal seams), their joint systematic analysis has been performed, with the focus made in the following three aspects: (i) prevention of rock burst under super-thick hard roof, (ii) deformation control of surrounding rock of roadways in the lower coal seam, and (iii) fire prevention in the goaf of working face. Given the strong bursting tendency observed in upper coal seam and lower coal seam, the technology of preventing rock burst under super-thick hard roof was proposed, which involved setting of narrow section coal pillars to protect roadways and interleaving layout of working faces. The specific supporting scheme of surrounding rock of roadways in the #3low1101 working face was determined, and the grouting reinforcement method of local fractured zones through Marithan was further proposed, to ensure the deformation control of surrounding rock of roadways in lower coal seams. The proposed fire prevention technology envisaged goaf grouting and spraying to plug leaks, which reduced the hazard of spontaneous combustion of residual coals in mined ultra-close coal seams. The technical and economic improvements with a direct economic benefit of 5.55 million yuan were achieved by the application of the proposed comprehensive technical support. The research results obtained provide a theoretical guidance and technical support of safe mining strategies of close coal seams in other mining areas.

scholarly journals Zoning Control Technology of Gob-Side Roadway Driving with Small Coal Pillar Facing Mining in a Special Isolated Island Working Face: A Case Study

2021 ◽  
Vol 11 (22) ◽  
pp. 10744
Author(s):  
Changliang Han ◽  
Houqiang Yang ◽  
Nong Zhang ◽  
Rijian Deng ◽  
Yuxin Guo
Keyword(s):  
Control Method ◽  
Coal Pillar ◽  
Control Technology ◽  
Stability Zone ◽  
Pressure Relief ◽  
Collaborative Control ◽  
Working Face ◽  
Underground Coal Mines ◽  
Engineering Practices

The gob-side roadway in an isolated island working face is a typical representative of a strong mining roadway, which seriously restricts the efficient and safe production of underground coal mines. With the engineering background of the main transportation roadway 1513 (MTR 1513) of the Xinyi Coal Mine, this paper introduces the engineering case of gob-side roadway driving with small coal-pillar facing mining in an isolated island working face under the alternate mining of wide and narrow working faces. Through comprehensive research methods, we studied zoning disturbance deformation characteristics and stress evolution law of gob-side roadway driving under face mining. Based on the characteristics of zoning disturbance, MTR 1513 is divided into three zones, which are the heading face mining zone, the mining influenced zone, and the mining stability zone. A collaborative control technology using pressure relief and anchoring is proposed, and the differentiated control method is formed for the three zones. For the heading face mining zone, the control method of anchoring first and then pressure relief is adopted; for the mining influenced zone, the control idea of synchronous coordination of pressure relief and anchorage is adopted; for the mining stability zone, the control method of anchoring without pressure relief is adopted. Engineering practices show that the disturbance influence distance of working face 1511 on MTR 1513 changes from 110 m advanced to 175 m delay. At this time, the surrounding rock deformation is effectively controlled, which verified the rationality of the division and the feasibility of three zoning control technology. The research results can provide reference for gob-side roadway driving with small coal pillar facing mining in a special isolated island working face.

Description of Large Deformation Problem Using Means of Visual Strain

2013 ◽  
Vol 275-277 ◽  
pp. 16-22
Author(s):  
You Liang Xu
Keyword(s):  
Constitutive Equation ◽  
Large Deformation ◽  
Strain Tensor ◽  
Visual Image ◽  
Linear Strain ◽  
Deformation Problem ◽  
Practical Engineering ◽  
Large Deformation Problem ◽  
Strain Tensors ◽  
Linear Strain Tensor

The constitutive equation of large deformation problem is closely related to geometric description. Nowadays, linear strain tensor is no longer unsuitable to describe large deformation. However, the existing non-linear strain tensors have complicated forms as well as no apparent geometric or physical meaning. While, the increment method is used to solve, however, convergence and efficiency are low sometimes. Thus the idea of visual strain tensor is proposed, with distinct meaning and visual image. Beside, it is likely to be used in engineering measurement, and it can be connected with measured constitutive equation directly. Thus this research provides a new idea and method for solving large-deformation problems in practical engineering.

scholarly journals Study on the Fracture Law of Inclined Hard Roof and Surrounding Rock Control of Mining Roadway in Longwall Mining Face

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5344
Author(s):  
Feng Cui ◽  
Shuai Dong ◽  
Xingping Lai ◽  
Jianqiang Chen ◽  
Chong Jia ◽  
...  
Keyword(s):  
Energy Release ◽  
Longwall Mining ◽  
Coal Pillar ◽  
High Energy ◽  
Mechanical Analysis ◽  
Engineering Practice ◽  
Analysis Model ◽  
Hard Roof ◽  
Working Face ◽  
The Stability

In the inclination direction, the fracture law of a longwall face roof is very important for roadway control. Based on the W1123 working face mining of Kuangou coal mine, the roof structure, stress and energy characteristics of W1123 were studied by using mechanical analysis, model testing and engineering practice. The results show that when the width of W1123 is less than 162 m, the roof forms a rock beam structure in the inclined direction, the floor pressure is lower, the energy and frequency of microseismic (MS) events are at a low level, and the stability of the section coal pillar is better. When the width of W1123 increases to 172 m, the roof breaks along the inclined direction, forming a double-hinged structure, the floor pressure is increased, and the frequency and energy of MS events also increases. The roof gathers elastic energy release, and combined with the MS energy release speed it can be considered that the stability of the section coal pillar is better. As the width of W1123 increases to 184 m, the roof in the inclined direction breaks again, forming a multi-hinged stress arch structure, and the floor pressure increases again. MS high-energy events occur frequently, and are not conducive to the stability of the section coal pillar. Finally, through engineering practice we verified the stability of the section coal pillar when the width of W1123 was 172 m, which provides a basis for determining the width of the working face and section coal pillar under similar conditions.

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