The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
Weili Gong - One of the best experts on this subject based on the ideXlab platform.
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an innovative approach for gob side entry retaining in thick coal seam Longwall Mining
Energies, 2017Co-Authors: Manchao He, Jun Yang, Weili GongAbstract:Gob-side entry retaining (GER) is a popular non-pillar Mining technique regarding how to reserve a gateroad for the use of next panel Mining. When used in thick coal seams, the conventional entry retaining method requires a huge amount of filling materials and may cause entry (gateroad) accidents. Thus, an innovative non-pillar Longwall Mining approach is introduced. First, structural and mechanical models were built to explore the mechanism of the new approach. The modeling results indicate that effective bulking of the gob roof and reasonable support of the entry roof were key governing factors in improving entry stabilities and reducing roof deformations. Accordingly, a directional roof fracturing technique was proposed to contribute to gob roof caving, and a constant resistance and large deformation anchor (CRLDA) cable was used to stabilize the entry roof. Subsequently, the evolutionary laws of the roof structure and stresses were explored using numerical simulation. It was found that the structure of the surrounding rocks around the retained entry changed significantly after roof fracturing. The stress-bearing center was transferred to the gob area, and the entry roof was in a low stress environment after adopting the approach. Finally, the approach was tested on a thick coal seam Longwall Mining panel. Field monitoring indicates that the retained entry was in a stable state and the index of the retained entry met the requirement of the next Mining panel. This work provides an effective and economical approach to non-pillar Longwall Mining in thick coal seams.
Kamran Goshtasbi - One of the best experts on this subject based on the ideXlab platform.
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calculation of periodic roof weighting interval in Longwall Mining using finite element method
Arabian Journal of Geosciences, 2014Co-Authors: Navid Hosseini, Kamran Goshtasbi, Behdeen Oraeemirzamani, Mehran GholinejadAbstract:The state of periodic loading and the interval of periodic roof weighting have an important role in geomechanical stability and, hence, in the continuity of Longwall Mining operations. In this paper, the mechanism of roof caving in Longwall Mining—together with the effect of engineering and geomechanical properties of surrounding rock masses on the magnitude and timing of periodic loading—is studied. For this purpose, a Longwall mine is first modeled using Phase2 software, and then, by simulating the roof caving process, the periodic roof weighting intervals is calculated. Based on the numerical modeling, the first roof weighting interval and the periodic roof weighting interval are calculated as 27.2 and 12.1 m, respectively. Sensitivity analysis is then applied to determine the effect of changes in the mechanical properties of the rock mass, especially in the main roof and immediate roof. The results of the analysis show that as GSI and quality of the immediate roof increases, the periodic roof weighting interval also increases. Hence, the applied algorithm in this research study can effectively be utilized to calculate the periodic roof weighting interval in the Longwall Mining method.
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studying the stress redistribution around the Longwall Mining panel using passive seismic velocity tomography and geostatistical estimation
Arabian Journal of Geosciences, 2013Co-Authors: Navid Hosseini, Kourosh Shahriar, Kazem Oraee, Kamran GoshtasbiAbstract:Generally, knowledge of stress redistribution around the Longwall panel causes a better understanding of the mechanisms that lead to ground failure, especially to rockbursts. In this paper, passive seismic velocity tomography is used to demonstrate the state of stress around the Longwall Mining panel. The Mining-induced microseismic events were recorded by mounting an array of receivers on the surface, above the active panel. To determine the location of seismic events and execute the process of tomography, double-difference method is employed as a local earthquake tomography. Since passive sources are used, the ray coverage is insufficient to achieve the quality images required. The wave velocity is assumed to be the regionalized variable and it is therefore estimated in a denser network, by using geostatistical estimation method. Subsequently, the three-dimensional images of wave velocity are created and are sliced into the coal seam. These images clearly illustrate the stressed zones that they are appropriately in compliance with the theoretical models. Such compliance is particularly apparent in the front abutment pressure and the side abutment pressure near the tailgate entry. Movements of the stressed zones along the advancing face are also evident. The research conclusion proves that the combined method, based on double-difference tomography and geostatistical estimation, can potentially be used to monitor stress changes around the Longwall Mining panel continuously. Such observation could lead to substantial improvement in both productivity and safety of Mining operations.
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passive seismic velocity tomography on Longwall Mining panel based on simultaneous iterative reconstructive technique sirt
Journal of Central South University, 2012Co-Authors: Navid Hosseini, Kourosh Shahriar, Kazem Oraee, Kamran GoshtasbiAbstract:Mining operation, especially underground coal Mining, always has the remarkable risks of ground control. Passive seismic velocity tomography based on simultaneous iterative reconstructive technique (SIRT) inversion is used to deduce the stress redistribution around the Longwall Mining panel. The Mining-induced microseismic events were recorded by mounting an array of receivers on the surface, above the active panel. After processing and filtering the seismic data, the three-dimensional tomography images of the p-wave velocity variations by SIRT passive seismic velocity tomography were provided. To display the velocity changes on coal seam level and subsequently to infer the stress redistribution, these three-dimensional tomograms into the coal seam level were sliced. In addition, the boundary element method (BEM) was used to simulate the stress redistribution. The results show that the inferred stresses from the passive seismic tomograms are conformed to numerical models and theoretical concept of the stress redistribution around the Longwall panel. In velocity tomograms, the main zones of the stress redistribution around the panel, including front and side abutment pressures, and gob stress are obvious and also the movement of stress zones along the face advancement is evident. Moreover, the effect of the advance rate of the face on the stress redistribution is demonstrated in tomography images. The research result proves that the SIRT passive seismic velocity tomography has an ultimate potential for monitoring the changes of stress redistribution around the Longwall Mining panel continuously and subsequently to improve safety of Mining operations.
Manchao He - One of the best experts on this subject based on the ideXlab platform.
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Longwall Mining method with roof cutting unloading and numerical investigation of ground pressure and roof stability
Arabian Journal of Geosciences, 2018Co-Authors: Zhaohua Li, Zhigang Meng, Manchao HeAbstract:As the energy demand for economic development continues to increase at a breakneck pace, shallow coal resources are increasingly being depleted and the scale and depth of Mining operations are growing substantially on a daily basis. Consequently, large deformations, coal bursts and other types of Mining hazards in conventional Longwall Mining are becoming increasingly severe owing to high rock pressures and the intense perturbations induced by Mining operations. To address these issues, we propose an innovative Longwall method with roof-cutting unloading for coal Mining. By using this method to apply cuts in the roof and relieve the rock pressure and by anchoring the roof of the roadway in advance, it was possible to let the goaf areas cave in and allow the formation of roadways. Moreover, this method makes no-pillar Mining possible. The control of the mine’s ground pressure is one of the most important topics in coal Mining research. The ground pressures measured during the application of the proposed method in actual coal operations are reported in this paper. Numerical analysis was carried out to compare the ground pressures and the roof stabilities obtained by the proposed method with those obtained by the conventional Longwall Mining method. The results confirmed the advantages of the proposed method.
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study of a no pillar Mining technique with automatically formed gob side entry retaining for Longwall Mining in coal mines
International Journal of Rock Mechanics and Mining Sciences, 2018Co-Authors: Manchao He, Jun Yang, Qi Wang, Bei Jiang, Hengchang YuAbstract:Abstract To reduce the roadway drivage ratio, drivage cost, and safety accidents, and increase the resource recovery ratio, a no-pillar Mining technique with automatically formed gob-side entry retaining is proposed for Longwall Mining. In this technique, pressure is offloaded via directional roof cutting, and a roadway is automatically formed via the ground pressure and rock breaking expansion. These processes permit the implementation of a new Longwall Mining process in which there is no Mining roadway and no reserves of coal pillars. In this paper, the concepts and key techniques (the technique of directional roof cutting, the formation technique of integrated coal side of the automatically formed gob-side entry retaining, the formation technique of gob-side gangue rib, and the support technique using a constant-resistance and large-deformation anchor cable) of no-pillar Mining with automatically formed gob-side entry retaining are introduced, and a field engineering test is performed. The test results are as follows: the no-pillar Mining concepts and technique with automatically formed gob-side entry retaining are feasible; all techniques and processes fully satisfy field production requirements; and the deformation of the automatically formed gob-side entry retaining is small, and the control effect is significant. These results prove that the no-pillar Mining technique with automatically formed gob-side entry retaining is feasible for Longwall Mining and achieves the goal of safe and efficient Mining.
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an innovative approach for gob side entry retaining in thick coal seam Longwall Mining
Energies, 2017Co-Authors: Manchao He, Jun Yang, Weili GongAbstract:Gob-side entry retaining (GER) is a popular non-pillar Mining technique regarding how to reserve a gateroad for the use of next panel Mining. When used in thick coal seams, the conventional entry retaining method requires a huge amount of filling materials and may cause entry (gateroad) accidents. Thus, an innovative non-pillar Longwall Mining approach is introduced. First, structural and mechanical models were built to explore the mechanism of the new approach. The modeling results indicate that effective bulking of the gob roof and reasonable support of the entry roof were key governing factors in improving entry stabilities and reducing roof deformations. Accordingly, a directional roof fracturing technique was proposed to contribute to gob roof caving, and a constant resistance and large deformation anchor (CRLDA) cable was used to stabilize the entry roof. Subsequently, the evolutionary laws of the roof structure and stresses were explored using numerical simulation. It was found that the structure of the surrounding rocks around the retained entry changed significantly after roof fracturing. The stress-bearing center was transferred to the gob area, and the entry roof was in a low stress environment after adopting the approach. Finally, the approach was tested on a thick coal seam Longwall Mining panel. Field monitoring indicates that the retained entry was in a stable state and the index of the retained entry met the requirement of the next Mining panel. This work provides an effective and economical approach to non-pillar Longwall Mining in thick coal seams.
Alex M Lechner - One of the best experts on this subject based on the ideXlab platform.
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the impact of underground Longwall Mining on prime agricultural land a review and research agenda
Land Degradation & Development, 2016Co-Authors: Alex M Lechner, Thomas Baumgartl, Phil Matthew, V GlennAbstract:Coal Mining and agriculture have repeatedly come into conflict when they co-occur. Although seemingly benign when compared with surface Mining, underground coal extraction techniques (including Longwall Mining) cause subsidence of agricultural land and loss of productivity. Despite growing concerns for global food security and increasing demand for coal resources, there is little peer-reviewed literature on the impacts of Longwall Mining in prime agricultural areas. In this paper, we examined the present knowledge of subsidence impacts of Longwall Mining on agriculture and how this may be interpreted for specific locations such as Australia. The review found that subsidence affects soil properties, hydrology and topography. The main impacts on agriculture are altered soil and groundwater hydrology, modified topography associated with increased erosion or waterlogging risk, and zones of compaction or cracking that cause soil physical and chemical changes. Agricultural productivity is also reduced through altering the types of farming practices that are suited to subsided non-uniform landscapes, decreasing farming efficiency through increasing paddock heterogeneity and decreasing ease of workability. There is a need to consider these multiple impacts under local conditions, with particular regard to the interaction of mine subsidence-associated disturbances with farming practices. We conclude by describing future research directions required for Australia and other countries outside of the USA—where most of the research has been conducted. Australia has unique soil and climatic conditions making extrapolation of studies from the USA on subsidence impacts and mitigation problematic.
Navid Hosseini - One of the best experts on this subject based on the ideXlab platform.
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calculation of periodic roof weighting interval in Longwall Mining using finite element method
Arabian Journal of Geosciences, 2014Co-Authors: Navid Hosseini, Kamran Goshtasbi, Behdeen Oraeemirzamani, Mehran GholinejadAbstract:The state of periodic loading and the interval of periodic roof weighting have an important role in geomechanical stability and, hence, in the continuity of Longwall Mining operations. In this paper, the mechanism of roof caving in Longwall Mining—together with the effect of engineering and geomechanical properties of surrounding rock masses on the magnitude and timing of periodic loading—is studied. For this purpose, a Longwall mine is first modeled using Phase2 software, and then, by simulating the roof caving process, the periodic roof weighting intervals is calculated. Based on the numerical modeling, the first roof weighting interval and the periodic roof weighting interval are calculated as 27.2 and 12.1 m, respectively. Sensitivity analysis is then applied to determine the effect of changes in the mechanical properties of the rock mass, especially in the main roof and immediate roof. The results of the analysis show that as GSI and quality of the immediate roof increases, the periodic roof weighting interval also increases. Hence, the applied algorithm in this research study can effectively be utilized to calculate the periodic roof weighting interval in the Longwall Mining method.
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studying the stress redistribution around the Longwall Mining panel using passive seismic velocity tomography and geostatistical estimation
Arabian Journal of Geosciences, 2013Co-Authors: Navid Hosseini, Kourosh Shahriar, Kazem Oraee, Kamran GoshtasbiAbstract:Generally, knowledge of stress redistribution around the Longwall panel causes a better understanding of the mechanisms that lead to ground failure, especially to rockbursts. In this paper, passive seismic velocity tomography is used to demonstrate the state of stress around the Longwall Mining panel. The Mining-induced microseismic events were recorded by mounting an array of receivers on the surface, above the active panel. To determine the location of seismic events and execute the process of tomography, double-difference method is employed as a local earthquake tomography. Since passive sources are used, the ray coverage is insufficient to achieve the quality images required. The wave velocity is assumed to be the regionalized variable and it is therefore estimated in a denser network, by using geostatistical estimation method. Subsequently, the three-dimensional images of wave velocity are created and are sliced into the coal seam. These images clearly illustrate the stressed zones that they are appropriately in compliance with the theoretical models. Such compliance is particularly apparent in the front abutment pressure and the side abutment pressure near the tailgate entry. Movements of the stressed zones along the advancing face are also evident. The research conclusion proves that the combined method, based on double-difference tomography and geostatistical estimation, can potentially be used to monitor stress changes around the Longwall Mining panel continuously. Such observation could lead to substantial improvement in both productivity and safety of Mining operations.
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passive seismic velocity tomography on Longwall Mining panel based on simultaneous iterative reconstructive technique sirt
Journal of Central South University, 2012Co-Authors: Navid Hosseini, Kourosh Shahriar, Kazem Oraee, Kamran GoshtasbiAbstract:Mining operation, especially underground coal Mining, always has the remarkable risks of ground control. Passive seismic velocity tomography based on simultaneous iterative reconstructive technique (SIRT) inversion is used to deduce the stress redistribution around the Longwall Mining panel. The Mining-induced microseismic events were recorded by mounting an array of receivers on the surface, above the active panel. After processing and filtering the seismic data, the three-dimensional tomography images of the p-wave velocity variations by SIRT passive seismic velocity tomography were provided. To display the velocity changes on coal seam level and subsequently to infer the stress redistribution, these three-dimensional tomograms into the coal seam level were sliced. In addition, the boundary element method (BEM) was used to simulate the stress redistribution. The results show that the inferred stresses from the passive seismic tomograms are conformed to numerical models and theoretical concept of the stress redistribution around the Longwall panel. In velocity tomograms, the main zones of the stress redistribution around the panel, including front and side abutment pressures, and gob stress are obvious and also the movement of stress zones along the face advancement is evident. Moreover, the effect of the advance rate of the face on the stress redistribution is demonstrated in tomography images. The research result proves that the SIRT passive seismic velocity tomography has an ultimate potential for monitoring the changes of stress redistribution around the Longwall Mining panel continuously and subsequently to improve safety of Mining operations.
