For the purpose to suit the bad mining technical conditions,such as deep imbed,gentle dip angle,and high initial stress in Dongguashan deposit,the stoping scheme was optimized.The new mining technique,with temporary c...For the purpose to suit the bad mining technical conditions,such as deep imbed,gentle dip angle,and high initial stress in Dongguashan deposit,the stoping scheme was optimized.The new mining technique,with temporary curtain walls,large panels and stopes,was achieved as well.The deposit model,which was built through the DATAMINE,was led into FLAC3D for numerical simulation.Based on these,the stabilities of pillars and stopes were analyzed.On the other hand,the impact of output stability by new scheme was verified with the help of optimization planning theory.The results show that stopes and curtain walls are safe when the width of temporary curtain walls between panels are 18 m.The length and width of stope increase to 78 m(82 m)and 18 m respectively,and those of panel increase to 300-500 m and 100 m respectively.The commercial test indicates that the new scheme can attain the aims of simpler production organization,better stope ventilation and work condition,smaller quantities of development and cutting,and 2/3 of equipments as before with the stable output.The pillar stoping technique is credible and valuable.展开更多
The problem of water preservation in mining and the prevention of water-bursts has been one of the more important issues in deep mining. Based on the concept of water-resisting key strata, the mechanics model of the k...The problem of water preservation in mining and the prevention of water-bursts has been one of the more important issues in deep mining. Based on the concept of water-resisting key strata, the mechanics model of the key strata is established given the structural characteristics and the mechanical properties of the roof rock layers of the working face in a particular coal mine. Four other models were derived from this model by rearranging the order of the layers in the key strata. The distribution characteristics of stress, deformation, pore pressure and the flow vector of all the models are computed using the analytical module of fluid-structure interaction in the FLAC software and the corresponding risks of a water-burst are analyzed. The results indicate that the water-insulating ability of the key strata is related to the arrangement of soft and hard rocks. The water-insulating ability of the compound water-resisting key strata (CWKS) with a hard-hard-soft-hard-soft compounding order is the best under the five given simulated conditions.展开更多
Following exploitation of a coal seam, the final stress field is the sum of in situ stress field and an excavation stress field. Based on this feature, we firstly established a mechanics analytical model of the mining...Following exploitation of a coal seam, the final stress field is the sum of in situ stress field and an excavation stress field. Based on this feature, we firstly established a mechanics analytical model of the mining floor strata. Then the study applied Fourier integral transform to solve a biharmonic equation,obtaining the analytical solution of the stress and displacement of the mining floor. Additionally, this investigation used the Mohr–Coulomb yield criterion to determine the plastic failure depth of the floor strata. The calculation process showed that the plastic failure depth of the floor and floor heave are related to the mining width, burial depth and physical–mechanical properties. The results from an example show that the curve of the plastic failure depth of the mining floor is characterized by a funnel shape and the maximum failure depth generates in the middle of mining floor; and that the maximum and minimum principal stresses change distinctly in the shallow layer and tend to a fixed value with an increase in depth. Based on the displacement results, the maximum floor heave appears in the middle of the stope and its value is 0.107 m. This will provide a basis for floor control. Lastly, we have verified the analytical results using FLAC3 Dto simulate floor excavation and find that there is some deviation between the two results, but their overall tendency is consistent which illustrates that the analysis method can well solve the stress and displacement of the floor.展开更多
To achieve safe and highly efficient mining in the gassy, deep mines of the Huainan collieries simultaneous coal and gas extraction, and the corresponding ventilation methods were developed. This includes a set of min...To achieve safe and highly efficient mining in the gassy, deep mines of the Huainan collieries simultaneous coal and gas extraction, and the corresponding ventilation methods were developed. This includes a set of mining procedures and principles which help insure safe and efficient production. Furthermore, green mining, meaning the comprehensive use of emitted gas, proper treatment of the environment and appropriate mine temperature control, is now standard. The concepts of modem mining and the principles of pressure relief are described. Coal-gas simultaneous ex- traction and multi-pressure relief techniques were developed which require a combination of surface and underground gas extraction. The application of Y-ventilation systems, of roadways retained along goafs, of stress control techniques for highly fragile mine roofs and of powerful, automatic and reliable mining equipment contributes to safe operation of modem deep mines. Operating parameters for these techniques are described and the results of their use discussed.展开更多
The distributed shear stress and the displacement across shear band, the evolution of plastic zones, and the load-carrying capacity of rock specimen were investigated in plane strain direct shear test according to Fas...The distributed shear stress and the displacement across shear band, the evolution of plastic zones, and the load-carrying capacity of rock specimen were investigated in plane strain direct shear test according to Fast Lagrangian Analysis of Continua （FLAC）. And then the shear displacement distribution in normal direction of system composed of localized shear band and elastic rock was analyzed based on gradient-dependent plasticity. The adopted failure criterion was a composite of Mohr-Coulomb criterion, that is, the relation between tension cut-off and postpeak constitutive of rock was linear strain-softening. Numerical results show that shear stress field approximately undergoes three different stages. At first, shear stress is only concentrated in the middle of top and base of specimen. Next, shear stress in the middle of specimen tends to increase, owing to superposition of shear stresses. Interestingly, two peaks of shear stress appear far from the loading ends of specimen, and the peaks approach with the increase in timestep until elements at the center of specimen yield. Finally, relatively lower shear stress level is reached in large part of specimen except in the regions near the two ends. As flow stress decreases, the analytical shear displacement distribution in shear band based on gradient-dependent plasticity becomes steeps outside the band, it is linear and its slope tends to decrease. These theoretical results qualitatively agree with that of the present numerical predicted results. Main advantage of the analytical solution over the numerical results according to FLAC is that it is continuous, smooth and non-linear （except at elastic stage）.展开更多
SEM tests were conducted on four kinds of typical deep rocks in Meilinmiao Mine, and the micro properties were analyzed. The particles of gritstone are unbroken and particle diameter ranges from 80 lam to 400 pro, and...SEM tests were conducted on four kinds of typical deep rocks in Meilinmiao Mine, and the micro properties were analyzed. The particles of gritstone are unbroken and particle diameter ranges from 80 lam to 400 pro, and the void between particles is wide. The macroscopic failure of gritstone is caused by breakage of the dung distributed between particles, and po- tassium feldspars contained in gritstone are not leached. The failure of medium sandstone is caused by micro cracks distributed in sandstone particles, and potassium feldspars are leached seriously, so the pores penetrate each other and there is close hy- draulic connection in medium sandstone. The particles of fine sandstone are broken, and the particle diameters range from 60 pm to 300 pm, which determines the pores have good connectivity between particles. The dolomites contained in fine sand- stone are corroded, and the micro fracture form belongs to inter-granular fracture. There are no particles and blocks in micro- structure of sandy mudstone, but there are diverse micro cracks. The failure of mudstone arises from the extension of micro cracks, and the microstructure is different from the other three kinds of sandstones obviously.展开更多
Based on field measurement, the relations was introduced between mining bepth and the peak value places of abutment pressures in long wall face of the deep colliery with caving method to handle goaf, and the reasons a...Based on field measurement, the relations was introduced between mining bepth and the peak value places of abutment pressures in long wall face of the deep colliery with caving method to handle goaf, and the reasons aod kinds of pressure bumps are analysed under the action of tbe moving and constant abutment pressures formed by the method of long wall caving or room and pillar mining, and the relative precautions were put foward to prevent the pressure bumps in deep mining.展开更多
Cooling energy needs, for mines in Northern Ontario, are mainly driven by the mining cooling technologies available and the cost to implement them in a 2500 m deep underground mine. The cooling technologies reviewed h...Cooling energy needs, for mines in Northern Ontario, are mainly driven by the mining cooling technologies available and the cost to implement them in a 2500 m deep underground mine. The cooling technologies reviewed herein include mechanical and natural cooling systems, ranging from mechanical chillers to seasonal thermal storages. The economic and operating parameters for each technology were estimated and evaluated according to the mine's energy loads. Including consideration of any combined heat and power benefits of the technology, cooling tower requirements, etc., the resulting cost of implementation for each technology could be ranked. This showed that the natural thermal storage systems and conventional chillers were the most cost-effective, mainly since the natural systems had very low operating cost and the chillers had relatively low capital costs.展开更多
基金Project(2004BA615204)supported by Key Technology Research and Development Program of ChinaProject(50574099)supported by the National Natural Science Foundation of China
文摘For the purpose to suit the bad mining technical conditions,such as deep imbed,gentle dip angle,and high initial stress in Dongguashan deposit,the stoping scheme was optimized.The new mining technique,with temporary curtain walls,large panels and stopes,was achieved as well.The deposit model,which was built through the DATAMINE,was led into FLAC3D for numerical simulation.Based on these,the stabilities of pillars and stopes were analyzed.On the other hand,the impact of output stability by new scheme was verified with the help of optimization planning theory.The results show that stopes and curtain walls are safe when the width of temporary curtain walls between panels are 18 m.The length and width of stope increase to 78 m(82 m)and 18 m respectively,and those of panel increase to 300-500 m and 100 m respectively.The commercial test indicates that the new scheme can attain the aims of simpler production organization,better stope ventilation and work condition,smaller quantities of development and cutting,and 2/3 of equipments as before with the stable output.The pillar stoping technique is credible and valuable.
基金Projects 50490270 supported by the National Natural Science Foundation of China, 50634050 the National Natural Science Foundation of China and 2006A038 SR Foundation of China University of Mining & Technology
文摘The problem of water preservation in mining and the prevention of water-bursts has been one of the more important issues in deep mining. Based on the concept of water-resisting key strata, the mechanics model of the key strata is established given the structural characteristics and the mechanical properties of the roof rock layers of the working face in a particular coal mine. Four other models were derived from this model by rearranging the order of the layers in the key strata. The distribution characteristics of stress, deformation, pore pressure and the flow vector of all the models are computed using the analytical module of fluid-structure interaction in the FLAC software and the corresponding risks of a water-burst are analyzed. The results indicate that the water-insulating ability of the key strata is related to the arrangement of soft and hard rocks. The water-insulating ability of the compound water-resisting key strata (CWKS) with a hard-hard-soft-hard-soft compounding order is the best under the five given simulated conditions.
基金the National Basic Research Program of China(No.2014CB046300)the National Natural Science Foundation of China(No.51174196)
文摘Following exploitation of a coal seam, the final stress field is the sum of in situ stress field and an excavation stress field. Based on this feature, we firstly established a mechanics analytical model of the mining floor strata. Then the study applied Fourier integral transform to solve a biharmonic equation,obtaining the analytical solution of the stress and displacement of the mining floor. Additionally, this investigation used the Mohr–Coulomb yield criterion to determine the plastic failure depth of the floor strata. The calculation process showed that the plastic failure depth of the floor and floor heave are related to the mining width, burial depth and physical–mechanical properties. The results from an example show that the curve of the plastic failure depth of the mining floor is characterized by a funnel shape and the maximum failure depth generates in the middle of mining floor; and that the maximum and minimum principal stresses change distinctly in the shallow layer and tend to a fixed value with an increase in depth. Based on the displacement results, the maximum floor heave appears in the middle of the stope and its value is 0.107 m. This will provide a basis for floor control. Lastly, we have verified the analytical results using FLAC3 Dto simulate floor excavation and find that there is some deviation between the two results, but their overall tendency is consistent which illustrates that the analysis method can well solve the stress and displacement of the floor.
基金Projects 2001BA803B04 and 2004BA803B01 supported by the National Key Projects for Tackling Scientific and Technological Problems during the 10thFive-Year Plan
文摘To achieve safe and highly efficient mining in the gassy, deep mines of the Huainan collieries simultaneous coal and gas extraction, and the corresponding ventilation methods were developed. This includes a set of mining procedures and principles which help insure safe and efficient production. Furthermore, green mining, meaning the comprehensive use of emitted gas, proper treatment of the environment and appropriate mine temperature control, is now standard. The concepts of modem mining and the principles of pressure relief are described. Coal-gas simultaneous ex- traction and multi-pressure relief techniques were developed which require a combination of surface and underground gas extraction. The application of Y-ventilation systems, of roadways retained along goafs, of stress control techniques for highly fragile mine roofs and of powerful, automatic and reliable mining equipment contributes to safe operation of modem deep mines. Operating parameters for these techniques are described and the results of their use discussed.
文摘The distributed shear stress and the displacement across shear band, the evolution of plastic zones, and the load-carrying capacity of rock specimen were investigated in plane strain direct shear test according to Fast Lagrangian Analysis of Continua （FLAC）. And then the shear displacement distribution in normal direction of system composed of localized shear band and elastic rock was analyzed based on gradient-dependent plasticity. The adopted failure criterion was a composite of Mohr-Coulomb criterion, that is, the relation between tension cut-off and postpeak constitutive of rock was linear strain-softening. Numerical results show that shear stress field approximately undergoes three different stages. At first, shear stress is only concentrated in the middle of top and base of specimen. Next, shear stress in the middle of specimen tends to increase, owing to superposition of shear stresses. Interestingly, two peaks of shear stress appear far from the loading ends of specimen, and the peaks approach with the increase in timestep until elements at the center of specimen yield. Finally, relatively lower shear stress level is reached in large part of specimen except in the regions near the two ends. As flow stress decreases, the analytical shear displacement distribution in shear band based on gradient-dependent plasticity becomes steeps outside the band, it is linear and its slope tends to decrease. These theoretical results qualitatively agree with that of the present numerical predicted results. Main advantage of the analytical solution over the numerical results according to FLAC is that it is continuous, smooth and non-linear （except at elastic stage）.
基金Supported by the Coal Joint Fund of the National Natural Science Foundation of China and Shenhua Group （U1261126） the Fundamental Research Fund for the Central Universities （2010YL09）
文摘SEM tests were conducted on four kinds of typical deep rocks in Meilinmiao Mine, and the micro properties were analyzed. The particles of gritstone are unbroken and particle diameter ranges from 80 lam to 400 pro, and the void between particles is wide. The macroscopic failure of gritstone is caused by breakage of the dung distributed between particles, and po- tassium feldspars contained in gritstone are not leached. The failure of medium sandstone is caused by micro cracks distributed in sandstone particles, and potassium feldspars are leached seriously, so the pores penetrate each other and there is close hy- draulic connection in medium sandstone. The particles of fine sandstone are broken, and the particle diameters range from 60 pm to 300 pm, which determines the pores have good connectivity between particles. The dolomites contained in fine sand- stone are corroded, and the micro fracture form belongs to inter-granular fracture. There are no particles and blocks in micro- structure of sandy mudstone, but there are diverse micro cracks. The failure of mudstone arises from the extension of micro cracks, and the microstructure is different from the other three kinds of sandstones obviously.
文摘Based on field measurement, the relations was introduced between mining bepth and the peak value places of abutment pressures in long wall face of the deep colliery with caving method to handle goaf, and the reasons aod kinds of pressure bumps are analysed under the action of tbe moving and constant abutment pressures formed by the method of long wall caving or room and pillar mining, and the relative precautions were put foward to prevent the pressure bumps in deep mining.
基金CEMI (Centre for Excellence in Mining Innovation) for their funding to support this research
文摘Cooling energy needs, for mines in Northern Ontario, are mainly driven by the mining cooling technologies available and the cost to implement them in a 2500 m deep underground mine. The cooling technologies reviewed herein include mechanical and natural cooling systems, ranging from mechanical chillers to seasonal thermal storages. The economic and operating parameters for each technology were estimated and evaluated according to the mine's energy loads. Including consideration of any combined heat and power benefits of the technology, cooling tower requirements, etc., the resulting cost of implementation for each technology could be ranked. This showed that the natural thermal storage systems and conventional chillers were the most cost-effective, mainly since the natural systems had very low operating cost and the chillers had relatively low capital costs.
