Stress Analysis of Upward Mining Displacement in Close-range Coal Seam Group

2021 ◽  
Keyword(s):  
Coal Seam ◽  
Stress Analysis ◽  
Close Range ◽  
Upward Mining

scholarly journals Vertical stress and stability of interburden over an abandoned pillar working before upward mining: a case study

2018 ◽  
Vol 5 (8) ◽  
pp. 180346 ◽  
Author(s):  
Jinwen Bai ◽  
Guorui Feng ◽  
Shanyong Wang ◽  
Tingye Qi ◽  
Jian Yang ◽  
...  
Keyword(s):  
Coal Seam ◽  
Initial Stress ◽  
Central Region ◽  
Coal Mine ◽  
Mechanical Analysis ◽  
Field Monitoring ◽  
Vertical Stress ◽  
Plastic Damage ◽  
Residual Coal ◽  
Upward Mining

Upward mining of the residual coal seam over an abandoned pillar working is one of the effective measures to alleviate the contradiction between limited resources and increased consumption. Interburden stability over an abandoned pillar working plays a significant role in guaranteeing the safety of upward mining; however, it has not yet been extensively studied and understood. In this study, the vertical stress of the interburden over an abandoned pillar working was first investigated. The mechanical model of the interburden was established and the damage conditions were analysed. Then, the stability of the interburden over 38502 abandoned workings in Baijiazhuang coal mine was determined by mechanical analysis and field monitoring. The results show that: (i) Vertical stress of the interburden over abandoned mining zones is clearly lower than the initial stress, indicating the existence of a de-stressed effect. Moreover, vertical stress of the interburden over residual coal pillars is greater than the initial stress, which is the evidence of a stress concentration effect. (ii) The interburden over an abandoned pillar working should be regarded as an elastic rectangular plate supported by generalized Kelvin bodies in mechanical modelling. (iii) The interburden over abandoned mining zones may experience two damage stages. In the first stage, initial plastic damage appears at the central region of interburden. In the second stage, the plastic damage evolves from the central point to the surrounding areas. (iv) The mechanical analysis and field monitoring both indicate the initial damage occurred at the central region over 38502 abandoned workings in Baijiazhuang coal mine before upward mining. Related rock control measures should be implemented in that region to guarantee the safe mining of the residual coal seam.

scholarly journals A Method for Determining Feasibility of Mining Residual Coal above Out-Fashioned Goaf under Variable Load: A Case Study

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Yuxia Guo ◽  
Honghui Yuan ◽  
Xiaogang Deng ◽  
Yujiang Zhang ◽  
Yunlou Du ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Coal Pillar ◽  
New Method ◽  
System Model ◽  
Variable Load ◽  
Residual Coal ◽  
Seam Mining ◽  
Suspended Roof ◽  
Upward Mining

Out-fashioned goaf is the protective structure for mining the upper residual coal, and its stability is the core problem in mining the upper residual coal. According to the upward mining demand for No. 5 coal seam above the out-fashioned goaf in Baizi Coal Mine, a new method is proposed to determine the upward mining safety. According to the analysis of the actual situation of the mine, the coal pillar and suspended roof in the out-fashioned goaf are taken as the objects. Furthermore, a “coal pillar-suspended roof” system model based on the variable load induced by abutment pressure of upper coal seam mining is established. After the mechanical model was solved, the parameter acquisition method of the model was established. The basic parameters of Baizi Coal Mine were considered to determine the feasibility of mining residual coal above out-fashioned goaf. And the effects of variable load on the coal pillar and suspended roof stability were analyzed. The results show that the upper No. 5 coal seam in Baizi Coal Mine can be mined safely. Compared to the traditional method, which simplifies all the upper loads to uniform loads, the new method is safer. The system stability of the suspended roof and coal pillar is influenced by “a/L” and “L.” Axial stress curves of the coal pillar and suspended roof appear nearly parabolic with “a/L” varying. Their maximum values are obtained when the “a/L” value is around 0.5∼0.6. In this situation, the combination structure is most easy to to be damaged. The ratio q′/q has a linear relationship with all stresses of the system model. The failure sequence of the system model is determined by analyzing the relationship between the tensile strength of the suspended roof and compressive strength of the coal pillar. This study provides a reference case for coal resources upward mining under similar conditions.

Research on Movement and Deformation of Rock Strata between Coal Seams in Pillar Upward Mining of Left-Over Coal with Numerical Simulation Method

2011 ◽  
Vol 225-226 ◽  
pp. 623-627
Author(s):  
Guo Rui Feng ◽  
Jing Zheng ◽  
Hong Fu Liu ◽  
Cong Ming Zhong
Keyword(s):  
Coal Seam ◽  
Control Function ◽  
Simulation Method ◽  
Vertical Displacement ◽  
Face Advance ◽  
Geological Condition ◽  
Coal Seams ◽  
Seam Mining ◽  
Rock Strata ◽  
Upward Mining

Based on the occurrence condition of coal seams and the geological condition on coal seam mining in Coal Mine Group Baijiazhuang, after pillar mining the 8th coal seam was well controlled, ascending mining the 6th coal seam, mining process was numerically simulated by FLAC3D,the variation law of displacements field on interlayer strata between the 6th coal seam and the 8th coal seam at different face advance were analyzed. Vertical displacement on rock strata increased gradually from below. A control stratum existed on rock strata and could play a control function for steady of strata movement, which provides a theory basis for further study on upward mining.

The Research and Detection Practice of Geological Radar Technology

2013 ◽  
Vol 838-841 ◽  
pp. 883-888
Author(s):  
Jin Song
Keyword(s):  
Coal Seam ◽  
High Precision ◽  
Ground Penetrating Radar ◽  
Drill Pipe ◽  
Basic Principles ◽  
Detection Technology ◽  
Depth Analysis ◽  
Close Range ◽  
Ground Penetrating

This document introduces basic principles of transmission in underground rock of ground penetrating radar (GPR) . Then an in-depth analysis on key parameters affecting the detection has been done, and detection resolution of radar are researched. By the technology, exploration experiments on Karst,little faults in coal seam and concealed metal drill pipe have been carried out. The results show that ground penetrating radar technology is a fast, efficient and intuitive geophysical detection technology, which provides a reliable technical means of solving the detection with close range and high precision.

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