scholarly journals A Study on the Impact of Longwall-Mining Operation on the Stability of a Slope-Pillar Structure

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Wenyong Bai ◽  
Jie Zhang ◽  
Bin Wang ◽  
Jianchen Zhang ◽  
Hongru Li ◽  
...  
Keyword(s):  
Structural Model ◽  
Longwall Mining ◽  
Movement Pattern ◽  
Mining Operation ◽  
Mining Operations ◽  
Working Face ◽  
The Stability ◽  
Pillar Structure ◽  
Boundary Width ◽  
The Impact

The slope-pillar structure is defined as an artificial construction shaped by a surface highwall mining and an underground longwall mining. In order to study the impact of stress variations (induced by the longwall-mining operations) on the stability of a slope-pillar structure, No. 30101-1 working face of Nanliang Coal Mine was selected as the study subject. A series of analysis including physical similar simulation test and the theoretical analysis were conducted to study the movement pattern of the overlying strata in the working face of the slope and the loading and the stability of the pillar column revealing the mechanism of dynamic load instability of nonuniformly distributed load “slope pillar.” A “slope-pillar” reverse sliding structural model was proposed along with a newly established “slope-pillar” structural mechanical model and a formula to calculate the boundary width of the protection for the pillar under the extreme balance conditions. According to the study, the width of the protective pillar is designed at 20 m, and the roadway deformation during the working face and the stability of the pillar can satisfy the safety requirement concerning the working face, which further validates the theoretic deduction formula.

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.

Study of the Trellis Support of Working Face Roadway in Impact Coal Seam

2014 ◽  
Vol 941-944 ◽  
pp. 2558-2564
Author(s):  
Yu Kai Lv ◽  
Cong Jiang ◽  
Yao Dong Jiang
Keyword(s):  
In Situ Stress ◽  
Surrounding Rock ◽  
Mine Pressure ◽  
Working Face ◽  
Coal Bumps ◽  
Roadway Support ◽  
The Stability ◽  
The Impact ◽  
Physical And Mechanical Characteristics

Coal bumps happened many times in mining at No.5 seam of Tangshan coal mine. Strengthen the roadway’s support of working face can effectively reduce disaster losses. With the research background of the 3654 working face, the mine pressure monitoring for the existing support form of roadway has been carried on. Perform a numerical simulation for the original roadway support, base on the in-situ stress and physical and mechanical characteristics of surrounding rock in experimental; study the impact of the stability of roadway’s surrounding rock, while the space change of trellis and change of supporting intensity; optimizing the original support form, so as to maximum reducing the impact of the coal bumps.

scholarly journals Stability of "Support-Surrounding Rock" System for Fully Mechanized Longwall Mining in Steeply Dipping Coal Seams

2021 ◽  
Author(s):  
Luo Shenghu ◽  
tong wang ◽  
Wu Yongping ◽  
Huangfu Jingyu ◽  
Zhao Huatao
Keyword(s):  
Coal Seam ◽  
Longwall Mining ◽  
Stability Control ◽  
Surrounding Rock ◽  
Coal Seams ◽  
Physical Test ◽  
Rock System ◽  
Working Face ◽  
The Stability ◽  
Mining Height

Abstract The key to the safe and efficient longwall mining of steeply dipping seams lies in the stability control of the "support-surrounding rock" system. This paper analyzes the difficulty of controlling the stability of the support during the longwall mining process of steeply dipping coal seams in terms of the characteristics of the non-uniform filled-in gob using a combination of physical test, theoretical analysis and field measurements. Considering the floor as an elastic foundation, we built a "support-surrounding rock" mechanical model based on data obtained on "support-surrounding rock" systems in different regions and the laws of support motion under different load conditions. Our findings are summarized as follows. First, depending on the angle of the coal seam, the caving gangue will roll (slide) downward along the incline, resulting in the formation of a non-uniform filling zone in the deep gob in which the lower, middle, and upper sections are filled, half-filled, and empty, respectively. In addition, an inverted triangular hollow surface is formed on the floor of the gob in the middle and upper sections behind the support. Furthermore, as the angle of the coal seam, length of the working face, and mining height increase, the characteristics of the non-uniform filled-in gob are enhanced. Second, we found that, as a result of support by the gangue, the "support-surrounding rock" system is relatively stable in the lower part of the working face while, in the middle and upper sections of the working face, the contact method and loading characteristics of the support are more complicated, making stability control difficult. Third, the magnitude and direction of the load, action point, and mining height all affect the stability of the support to varying degrees, with the tangential load and action position of the roof load having the most significant impacts on the stability of the support. Under loading by the roof, rotation and subsidence of the support inevitably occur, with gradually increasing amplitude and effects on the inter-support and sliding forces. Finally, we found that it is advisable in the process of moving the support to adopt "sliding advance of support" measures and to apply a "down-up" removal order to ensure overall stability. These research results provide reference and guidance of significance to field practice production.

scholarly journals Analysis of Stress-Strain States in the Vicinity of Mining Excavations in a Rock Mass with Variable Mechanical Properties

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5567
Author(s):  
Marek Jendryś ◽  
Stanisław Duży ◽  
Grzegorz Dyduch
Keyword(s):  
Mechanical Properties ◽  
Rock Mass ◽  
Numerical Simulations ◽  
Mechanical Parameters ◽  
Mining Operations ◽  
Axial Forces ◽  
Internal Forces ◽  
Random Variability ◽  
The Stability ◽  
The Impact

Rock mass is a medium created through processes that have lasted over four billion years, and its intrinsic feature is the variability of the parameters that describe it. A particularly high variability of mechanical parameters is observed in Carboniferous sedimentary and metamorphic rocks. The mechanical properties, especially the rock mass strength, are essential for the design and maintenance of the stability of excavations conducted in it and for the safe conduct of mining operations. This article presents the test results confirming the random variability of the mechanical parameters of the rock mass. The second part of the article presents the results of numerical simulations mapping the Carboniferous rock mass along with a 1000 m deep tunnel excavation protected by steel arch supports. Numerical simulations were carried out for models with different variability coefficients of strength and deformation parameters, and the obtained results were analyzed in terms of damage zones and rock mass stress state as well as axial forces in the modelled supports. The results of the simulation demonstrate the impact of the variability of rock mass properties on its state in the vicinity of the excavation and, consequently, on the internal forces in the steel supports and their uneven loading along the length of the excavation. This fact should be taken into account in their design.

scholarly journals Comparative analysis of the mine pressure at non-pillar longwall mining by roof cutting and traditional longwall mining

2019 ◽  
Vol 16 (2) ◽  
pp. 423-438 ◽  
Author(s):  
Peng Zhou ◽  
Yajun Wang ◽  
Guolong Zhu ◽  
Yubing Gao
Keyword(s):  
Pressure Distribution ◽  
Coal Mining ◽  
Longwall Mining ◽  
Mining Industry ◽  
Mine Pressure ◽  
Mining Method ◽  
Working Face ◽  
Distribution Features ◽  
Mining Pressure ◽  
The Stability

Abstract Non-pillar coal mining has been developed and implemented in the recent decades in China's coal mining industry. The non-pillar longwall mining by roof cutting without pre-excavated entry (N00 mining method) is one of the latest non-pillar mining methods and this method has the advantages of reduced roadway drivage ratio and increased resource recovery ratio. Previous studies show that the mining pressure during the working face advancing is one of the main factors that affect the stability of underground structures and the safety production. However, there is no evaluation or analysis of the mining pressure at the mining face using entry retaining with roof pre-cutting and an absence of pre-excavated tail entry. In this paper, both field monitoring and numerical simulation approaches are employed in the analysis of the mining pressure distribution characteristics within a range of the whole working face during the face advancing. The results are compared with the field data and simulation results from the traditional mining method performed in the same coal mine. Results supported the idea that the N00 mining method can generate a low-stress area for the retained entry. The stability of the working face and retained entry can be well maintained due to the mine pressure optimization. This paper can aid in the understanding of structural mechanic modeling and mine pressure distribution features, structural mechanic analysis and mine pressure distribution features of the N00 mining method.

Research on Stability of Overburden Structure around Longwall Mining Face in Steeply Dipping Seam Group

2015 ◽  
Vol 724 ◽  
pp. 100-110
Author(s):  
Shi Guang Ren ◽  
Yong Ping Wu ◽  
Jian Hui Yin
Keyword(s):  
Coal Seam ◽  
Longwall Mining ◽  
Coal Pillar ◽  
Beam Theory ◽  
Coal Seams ◽  
Working Face ◽  
Rock Structure ◽  
Longitudinal Bending ◽  
Mining Face ◽  
The Stability

The steeply dipping seam group is defined by the two or more coal seams ,a pitch between 35°~55°. Using masonry beam theory, longitudinal bending theory and “R-S-F” dynamics control theory built a lower area overburden structure mode. Analysed the stability of low position coal seam. The balance requirement and the strength of the structure which is affected by the caving rock and lower coal roof were given. It easily generates two lower position steps rock structure in inclination along working face. Regular breaking of the second structure is the main reason leads to the imbalance of the structure between upper coal pillar and upper coal mining face.The interaction among multiple coal seam panels and overburden structures is the main reason that causes the rock disaster, the unbalance of the lower area may lead to pushing accident, the imbalance of the upper area can generate shock pressure.

scholarly journals Mechanical analysis of the structure of longwall mining hydraulic support

2020 ◽  
Vol 103 (3) ◽  
pp. 003685042093647
Author(s):  
Tengda Li ◽  
Jiren Wang ◽  
Kun Zhang ◽  
Chunhua Zhang
Keyword(s):  
Coal Seam ◽  
Support Group ◽  
Production Efficiency ◽  
Mechanical Characteristics ◽  
Longwall Mining ◽  
Transverse Load ◽  
Mining Operations ◽  
Hydraulic Support ◽  
Working Face ◽  
Hydraulic Supports

Existing studies of the structural strength of longwall mining hydraulic support are mainly focused on the force acting on individual supports instead of the general mechanical characteristics of the support group in a fully mechanized coal seam working face. This study combines theoretical analyses and experiments to investigate the mechanical characteristics of a longwall mining hydraulic support group and the stiffness of key support components under different working conditions. The theory of a beam on an elastic foundation was applied to construct a mechanical model for the hydraulic support group. The location and the size of loads on the top beam were determined. Field tests yielded data on the deflection of the roof and loading on the support group along the working face, where the stiffness of end supports varies. The transverse load distribution of the top beam and the offset loading coefficient at different locations along the working-face direction were obtained. A three-dimensional model was constructed for the support group while assembling virtual hydraulic supports using modern virtual modeling theories and methods. Finite element analysis was used to analyze the strength of the hydraulic support. The weakest areas of key components were found to be pinholes connecting the column cylinder to the base and roof of the mine. These results can be applied to achieve secure and stable operations of hydraulic supports in the working face of a thin coal seam, thereby improving the safety and production efficiency of mining operations.

scholarly journals Impact of the Mining Dimensions on the Stability of Backfilled Pier-Columns

2021 ◽  
Vol 11 (20) ◽  
pp. 9640
Author(s):  
Jianlin Xie ◽  
Weibing Zhu ◽  
Jialin Xu ◽  
Xiaozhen Wang ◽  
Limin Wang
Keyword(s):  
Physical Simulation ◽  
Three Dimensional ◽  
Field Testing ◽  
Mining Areas ◽  
Working Face ◽  
Physical Experiments ◽  
Mining Width ◽  
The Stability ◽  
The Impact

Owing to alternate mining of the new and old mining areas on sites, the mining thickness and width of the working face for pier-column backfilling varies. Thus, there is an urgent need to determine the impact on the bearing performance of the backfilled pier-column after changing the mined dimensions. This study consisted of three-dimensional numerical simulations, physical experiments, and field testing. These methods were performed to study the impact on the stability of the backfilled pier-column after changing the dimensions of the working face. The numerical and physical simulation results revealed that the mining thickness has a greater impact on the stability of the backfilled pier-columns than the width. Field testing results proved that the designed parameters for the backfilled pier-column in situ satisfy the bearing requirements; thus, it can effectively support the overlying strata of the goaf after mining. When increasing the mining thickness, the stress borne by the pier-column increased, and its stability decreased. Upon increasing the mining width, the variation in the stress exerted onto the pier-column was remarkably small, and the change of the elastoplastic zone of the pier-column was also minimal.

High rates of cannibalism and food waste consumption by dingoes living at a remote mining operation in the Great Sandy Desert, Western Australia

2020 ◽  
Vol 42 (2) ◽  
pp. 230
Author(s):  
Bradley P. Smith ◽  
Damian S. Morrant ◽  
Anne-Louise Vague ◽  
Tim S. Doherty
Keyword(s):  
Western Australia ◽  
Resource Availability ◽  
Food Resource ◽  
Mining Operation ◽  
Sandy Desert ◽  
Potential Influence ◽  
Mining Operations ◽  
Dietary Analysis ◽  
Water Provision ◽  
The Impact

Mining operations in remote Australia represent a unique opportunity to examine the impact of supplementary food and water provision on local wildlife. Here, we present a dietary analysis of dingoes living at a mine site in the Great Sandy Desert, Western Australia. A total of 270 faeces (scats) were collected from across the mine footprint on two occasions three months apart. The most frequently consumed food resource was anthropogenic (rubbish), which was found in 218 of 270 faeces (80.7% of scats and 65.3% of scat volume). Also of note was a high proportion of dingo remains, which was found in 51 of 270 faeces (18.9% of scats and 10.4% of scat volume), suggesting the occurrence of cannibalism. These findings highlight the potential influence of human-modified areas and associated resource availability on the diet of dingoes, and have implications for the environmental management of areas surrounding mining operations.

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