We tested for fourteen trace elements in samples collected from the Ordovician strata in Datun coal field. The vertical concentration variation of these trace dements is reported. The relationship of the variation to ...We tested for fourteen trace elements in samples collected from the Ordovician strata in Datun coal field. The vertical concentration variation of these trace dements is reported. The relationship of the variation to the water-bearing capacity of the Ordovician strata is discussed. The minimum concentration of eleven (of 14 total) trace elements appears in the lower Majiagou formation. The maximum concentrations mainly appear in the Badou and Jiawang formations: eight maxima are located in Badou and four more are in Jiawang. The study of karst development and the water-bearing capacity of Ordovician strata shows that karst is well developed in the Majiagou formation and there is a consequent high water-bearing capacity in this formation: Badou and Jiawang formations are contrary to this situation. The results illustrate that the minimum concentrations of most trace elements within certain Ordovician formations can be taken as strong evidence for the existence of a well developed karst and a high water-bearing capacity.展开更多
It is discussed features and tbe producing mechanism of buried geological information in geological, geophysical and remote sensing data in Huaibei coal field, and studied the methods extracting buried tectonic and ig...It is discussed features and tbe producing mechanism of buried geological information in geological, geophysical and remote sensing data in Huaibei coal field, and studied the methods extracting buried tectonic and igneous rock information from various geologicaI data using digital image processing techoiques.展开更多
This paper focuses on the village coal pillar under huge thick loose bed and thin bedrock over high prelatic water level at the north of the Yellow River. The strip mining technology was used to protect the village ho...This paper focuses on the village coal pillar under huge thick loose bed and thin bedrock over high prelatic water level at the north of the Yellow River. The strip mining technology was used to protect the village houses. The stratum structure control action of mining subsidence was used to design the mining and pillar width. To further raise resources recovery, we adopted the mutative scheme of mining and pillar width. Observation was carried out while mining. Research shows there is feasibility of the strip mining technology to protecting the village buildings of the village coal pillar under huge thick loose bed and thin bedrock over high prelatic water level at the north of the Yellow River. Finally, subsidence parameters of strip mining were obtained. It is the basic data of the strip mining of the coal field at the north of the Yellow River.展开更多
In this paper, Xinjiang's coal field is selected as the investigation area. Through a series of field surveys in Xinjiang, we made the small-scale area analysis of coal field fire using the ground remote sensing tech...In this paper, Xinjiang's coal field is selected as the investigation area. Through a series of field surveys in Xinjiang, we made the small-scale area analysis of coal field fire using the ground remote sensing technique, and presented the reasonable evaluation of thermal anomaly conditions of Xinjiang's coal field arising from coal self-ignition fires. The results show that the method of small-scale area analysis is available for examining the extinguished actuality of coal fires and detecting fire spots. Therefore, for the selected fire-extlngulshed coal field in Xinjiang, the fire extinguishing effect was effectively analyzed by the means, and the new hidden thermal dangers were sought and diagnosed. For the coal field where the fire has not been extinguished, the utilization of this means approximately identified the severity and range of the fire area, and provided the quantitative and ground references for extinguish engineering.展开更多
The spontaneous burning has been lasting for thousands of years in the coal fields in the north of China. It spreads from the west (Tianshan coal field) to the east (Huolinhe coal field). Its E-W extension is up to 37...The spontaneous burning has been lasting for thousands of years in the coal fields in the north of China. It spreads from the west (Tianshan coal field) to the east (Huolinhe coal field). Its E-W extension is up to 3750km, concentrating in N35°toN45°, its vertical depth up to 260m, and the surface temprature locally up to 270℃. Annually, it burns out 0, 250-300 million tones of coal, causing economic loss equivalent to 2-3 billion R.M.B. Yuan.It destroies coal resources and causes hazards in coal mines. In order to locate the extent and the direction in coal burning areas, the remote sensing technique has heen used and has produced an obvious benefit.展开更多
Underground coal fires are one of the most common and serious geohazards in most coal producing countries in the world. Monitoring their spatio-temporal changes plays an important role in controlling and preventing th...Underground coal fires are one of the most common and serious geohazards in most coal producing countries in the world. Monitoring their spatio-temporal changes plays an important role in controlling and preventing the effects of coal fires, and their environmental impact. In this study, the spatio-temporal changes of underground coal fires in Khanh Hoa coal field(North-East of Viet Nam) were analyzed using Landsat time-series data during the 2008-2016 period. Based on land surface temperatures retrieved from Landsat thermal data, underground coal fires related to thermal anomalies were identified using the MEDIAN+1.5×IQR(IQR: Interquartile range) threshold technique. The locations of underground coal fires were validated using a coal fire map produced by the field survey data and cross-validated using the daytime ASTER thermal infrared imagery. Based on the fires extracted from seven Landsat thermal imageries, the spatiotemporal changes of underground coal fire areas were analyzed. The results showed that the thermalanomalous zones have been correlated with known coal fires. Cross-validation of coal fires using ASTER TIR data showed a high consistency of 79.3%. The largest coal fire area of 184.6 hectares was detected in 2010, followed by 2014(181.1 hectares) and 2016(178.5 hectares). The smaller coal fire areas were extracted with areas of 133.6 and 152.5 hectares in 2011 and 2009 respectively. Underground coal fires were mainly detected in the northern and southern part, and tend to spread to north-west of the coal field.展开更多
The mineralogy and geochemistry data are presented for thirty-seven shales, four concretions, two carbonate sediments and seven lignites from the Marathousa coal field of the Megalopolis Basin in Greece. The argillace...The mineralogy and geochemistry data are presented for thirty-seven shales, four concretions, two carbonate sediments and seven lignites from the Marathousa coal field of the Megalopolis Basin in Greece. The argillaceous rocks consist of chlorite, illite, kaolinite, albite,quartz, opal-A, calcite and dolomite; the concretions of aragonite, gypsum and pyrite; and the carbonate rocks of calcite, quartz and illite. The mineral matter in the lignites consists of gyp-sum, quartz, albite, chlorite, illite, opal-A, dolomite, pyrite, and rarely calcite and kaolinite.A three-factor model explains the total variation of major and trace elements in the argillaceous sediments. The first factor is an aluminosilicate factor and involves the following elements: Al,Si, Mg, Na, K, Ti, Mn, Nb, Y, Rb, Zn, Cu, Ni, Cr, Nd and V, associated with chlorite,albite and illite. The second factor involves the elements Ca, Sr, Ba, Zn and Sc and is related to carbonate lithology and mainly the carbonate concretions with gypsum. The third factor in-volves Fe and Ce with a weak association with Mn. The diagenesis of the Marathousa sedi-ments and lignites was ot very advanced as indicated by (a) the total thickness of the sequence (500 m), (b) the presence of biogenic silica (opal-A) and (c) the age of the deposit (Pleis-tocene). For these reasons the presence of chlorite, illite and kaolinite in the sediments and lig-nite is due not to diagenetic reactions but to weathering of the flysch and metamorphic rocks at the edges of the Megalopolis Basin and transport of the weathering products (illite, chlorite,kaolinite) into the basin of deposition. The diagenetic minerals of the Marathousa sequence in-clude pyrite, gypsum, dolomite and aragonite.展开更多
Taking the return air roadway of Tashan 8204 isolated island working face as the background, the evolution law of the stress field in the surrounding rock of the widened coal pillar area roadway during the mining peri...Taking the return air roadway of Tashan 8204 isolated island working face as the background, the evolution law of the stress field in the surrounding rock of the widened coal pillar area roadway during the mining period of the isolated island working face is obtained through numerical simulation. The hazardous area of strong mine pressure under different coal pillar widths is determined. Through simulation, it is known that when the width of the coal pillar is less than 20 m, there is large bearing capacity on the coal side of the roadway entity. The force on the side of the coal pillar is relatively small. When the width of the coal pillar ranges from 25 m to 45 m, the vertical stress on the roadway and surrounding areas is relatively high. Pressure relief measures need to be taken during mining to reduce surrounding rock stress. When the width of the coal pillar is greater than 45 m, the peak stress of the coal pillar is located in the deep part of the surrounding rock, but it still has a certain impact on the roadway. It is necessary to take pressure relief measures to transfer the stress to a deeper depth to ensure the stability of the triangular coal pillar during the safe mining period of the working face. This provides guidance for ensuring the stability of the triangular coal pillar during the safe mining period of the working face.展开更多
The exact shape and size of the gasification channel during underground coal gasification(UGC) are of vital importance for the safety and stability of the upper parts of the geological formation.In practice existing g...The exact shape and size of the gasification channel during underground coal gasification(UGC) are of vital importance for the safety and stability of the upper parts of the geological formation.In practice existing geological measurements are insufficient to obtain such information because the coal seam is typically deeply buried and the geological conditions are often complex.This paper introduces a cylindrical model for the gasification channel.The rock and soil masses are assumed to be homogeneous and isotropic and the effect of seepage on the temperature field was neglected.The theory of heat conduction was used to write the equation predicting the temperature field around the gasification channel.The idea of an excess temperature was introduced to solve the equations.Applying this model to UCG in the field for an influence radius,r,of 70 m gave the model parameters,u1,2,3...,of 2.4,5.5,8.7...By adjusting the radius(2,4,or 6 m) reasonable temperatures of the gasification channel were found for 4 m.The temperature distribution in the vertical direction,and the combustion volume,were also calculated.Comparison to field measurements shows that the results obtained from the proposed model are very close to practice.展开更多
Spontaneous combustion of coal seam has been and continues to be a big problem in coal mines. It could pose great threat to the safety of the whole mine and all miners, especially when it occurs in or nearby coal mine...Spontaneous combustion of coal seam has been and continues to be a big problem in coal mines. It could pose great threat to the safety of the whole mine and all miners, especially when it occurs in or nearby coal mines. Besides, environment of area surrounded mines during combustion can be threatened where large amount of toxic gases including CO_2, CO, SO_2 and H_2S can be leased by fire in mine. Hence, it is important and significant for scholars to study the controlling and preventing of the coal seam fire. In this paper, the complicated reasons for the occurrence and development of spontaneous combustion in coal seam are analysed and different models under various air leakage situations are built as well. Based on the model and approximately calculation, the difficulty of fire extinguishment in coal seam is pointed out as the difficulty and poor effect to remove the large amount of heat released. Detailed measurements about backfilling and case analyses are also provided on the basis of the recent ten years' practice of controlling spontaneous combustion in coal seams in China. A technical fire prevention and control method has been concluded as five steps including detection, prevention, sealing, injection and pressure adjustment. However, various backfill materials require different application and environmental factors, so in this paper, analyses and discussion about the effect and engineering application of prevention of spontaneous combustion are provided according to different backfilling technologies and methods. Once the aforementioned fire prevention can be widely applied and regulated in mines, green mining will be achievable concerning mine fire prevention and control.展开更多
Two design axioms and axiomatic approach were discussed. As an example of application, design process of a new style single prop was illustrated in term of axi- oms.
A local thermal stress model of water-cooled-wall pulverized-coal gasifier was built, and ANSYS was used to simulate the stress field in the gasifier operation to research the damage of refractories and slag layer cau...A local thermal stress model of water-cooled-wall pulverized-coal gasifier was built, and ANSYS was used to simulate the stress field in the gasifier operation to research the damage of refractories and slag layer caused by the thermal stress. The results reveal that:(1) the maximum stress of water-cooled-wall gasifier appears at the interface between anchor nails and refractories as well as the interface between refractories and the slag layer, and the maximum stress of slag layer appears on the surface of the slag layer;(2) the increase of slag layer thickness can significantly reduce the thermal stress at the interface between anchor nails and refractories, but increase the thermal stress between slag layer and refractories;(3) when the therma I conductivity is 2-6 W · m-1 · K-1, the thermal stress increases rapidly with the increase of the thermal conductivity, but when the thermal conductivity is 6-10 W · m-1 · K-1, the thermal stress is basically stable;(4) the higher the cooling rate, the faster the decreasing speed of the temperature and thermal stress.展开更多
In this study, the spatial distributions of stress and fracture fields for three typical underground coal mining layouts, Le, non-pillar mining (NM), top-coal caving mining (TCM) and protective coal-seam mining (...In this study, the spatial distributions of stress and fracture fields for three typical underground coal mining layouts, Le, non-pillar mining (NM), top-coal caving mining (TCM) and protective coal-seam mining (PCM), are modeled using discrete element software UDEC, The numerical results show that different mining layouts can lead to different mining-induced stress fields, resulting in diverse fracture fields, For the PCM, the mining influenced area in front of the mining faces is the largest, and the stress concentration factor in front of the mining faces is the lowest, The spatial shapes of the mining-induced fracture fields under NM, TCM and PCM differ, and they are characterized by trapezoidal, triangular and tower shapes, respectively, The fractal dimensions of mining-induced fractures of the three mining layouts decrease in the order of PCM, TCM and NM, It is also shown that the PCM can result in a better gas control effect in coal mines with high outburst potential, The numerical results are expected to provide a basis for understanding of mining-induced gas seepage fields and provide a reference for high- efficiency coal mining,展开更多
Study on tectonic fractures based on the inversion of tectonic stress fields is an effective method. In this study, a geological model was set up based on geological data from the Hudi Coal Mine, Qinshui Basin, a mech...Study on tectonic fractures based on the inversion of tectonic stress fields is an effective method. In this study, a geological model was set up based on geological data from the Hudi Coal Mine, Qinshui Basin, a mechanical model was established under the condition of rock mechanics and geostress, and the finite element method was used to simulate the paleotectonic stress field. Based on the Griffith and Mohr-Coulomb criterion, the distribution of tectonic fractures in the Shanxi Formation during the Indosinian, Yanshanian, and Himalayan period can be predicted with the index of comprehensive rupture rate. The results show that the acting force of the Pacific Plate and the India Plate to the North China Plate formed the direction of principal stress is N-S, NW - SE, and NE - SW, respectively, in different periods in the study area. Changes in the direction and strength of the acting force led to the regional gradients of tectonic stress magnitude, which resulted in an asymmetrical distribution state of the stress conditions in different periods. It is suggested that the low-stress areas are mainly located in the fault zones and extend along the direction of the fault zones. Furthermore, the high-stress areas are located in the junction of fold belts and the binding site of multiple folds. The development of tectonic fractures was affected by the distribution of stress intensity and the tectonic position of folds and faults, which resulted in some developed areas with level I and II. There are obvious differences in the development of tectonic fractures in the fold and fault zones and the anticline and syncline structure at the same fold zones. The tectonic fractures of the Shanxi Formation during the Himalayan period are more developed than those during the Indosinian and Yanshanian period due to the superposition of the late tectonic movement to the early tectonic movement and the differences in the magnitude and direction of stress intensity.展开更多
A brief account of the development of the research on mining earthquakes and the general situation of the Mentougou Coal Mine medium scale experiment field for earthquake prediction and the project of monitor and p...A brief account of the development of the research on mining earthquakes and the general situation of the Mentougou Coal Mine medium scale experiment field for earthquake prediction and the project of monitor and prediction is given. The differences of waveforms between mining earthquakes and natural earthquakes is discussed. The magnitude frequency distribution of the 79 000 mining earthquakes of over M L1.0 from 1984 to 1995 is summarized . Finally, taking PH and PV, the principal compressive stress components of the focal mechanism of the mining earthquakes, as the criteria, analyses the stress background of the 12 large mining earthquakes.展开更多
文摘We tested for fourteen trace elements in samples collected from the Ordovician strata in Datun coal field. The vertical concentration variation of these trace dements is reported. The relationship of the variation to the water-bearing capacity of the Ordovician strata is discussed. The minimum concentration of eleven (of 14 total) trace elements appears in the lower Majiagou formation. The maximum concentrations mainly appear in the Badou and Jiawang formations: eight maxima are located in Badou and four more are in Jiawang. The study of karst development and the water-bearing capacity of Ordovician strata shows that karst is well developed in the Majiagou formation and there is a consequent high water-bearing capacity in this formation: Badou and Jiawang formations are contrary to this situation. The results illustrate that the minimum concentrations of most trace elements within certain Ordovician formations can be taken as strong evidence for the existence of a well developed karst and a high water-bearing capacity.
文摘It is discussed features and tbe producing mechanism of buried geological information in geological, geophysical and remote sensing data in Huaibei coal field, and studied the methods extracting buried tectonic and igneous rock information from various geologicaI data using digital image processing techoiques.
文摘This paper focuses on the village coal pillar under huge thick loose bed and thin bedrock over high prelatic water level at the north of the Yellow River. The strip mining technology was used to protect the village houses. The stratum structure control action of mining subsidence was used to design the mining and pillar width. To further raise resources recovery, we adopted the mutative scheme of mining and pillar width. Observation was carried out while mining. Research shows there is feasibility of the strip mining technology to protecting the village buildings of the village coal pillar under huge thick loose bed and thin bedrock over high prelatic water level at the north of the Yellow River. Finally, subsidence parameters of strip mining were obtained. It is the basic data of the strip mining of the coal field at the north of the Yellow River.
基金the National Natural Science Foundation of China (Grant Nos. 50606033 and50674079 )National High Technology Research and Development Program of China ( Grant No.2007AA04Z178)
文摘In this paper, Xinjiang's coal field is selected as the investigation area. Through a series of field surveys in Xinjiang, we made the small-scale area analysis of coal field fire using the ground remote sensing technique, and presented the reasonable evaluation of thermal anomaly conditions of Xinjiang's coal field arising from coal self-ignition fires. The results show that the method of small-scale area analysis is available for examining the extinguished actuality of coal fires and detecting fire spots. Therefore, for the selected fire-extlngulshed coal field in Xinjiang, the fire extinguishing effect was effectively analyzed by the means, and the new hidden thermal dangers were sought and diagnosed. For the coal field where the fire has not been extinguished, the utilization of this means approximately identified the severity and range of the fire area, and provided the quantitative and ground references for extinguish engineering.
文摘The spontaneous burning has been lasting for thousands of years in the coal fields in the north of China. It spreads from the west (Tianshan coal field) to the east (Huolinhe coal field). Its E-W extension is up to 3750km, concentrating in N35°toN45°, its vertical depth up to 260m, and the surface temprature locally up to 270℃. Annually, it burns out 0, 250-300 million tones of coal, causing economic loss equivalent to 2-3 billion R.M.B. Yuan.It destroies coal resources and causes hazards in coal mines. In order to locate the extent and the direction in coal burning areas, the remote sensing technique has heen used and has produced an obvious benefit.
基金funded by the Ministry-level Scientific and Technological Key Programs of Ministry of Natural Resources and Environment of Viet Nam "Application of thermal infrared remote sensing and GIS for mapping underground coal fires in Quang Ninh coal basin" (Grant No. TNMT.2017.08.06)
文摘Underground coal fires are one of the most common and serious geohazards in most coal producing countries in the world. Monitoring their spatio-temporal changes plays an important role in controlling and preventing the effects of coal fires, and their environmental impact. In this study, the spatio-temporal changes of underground coal fires in Khanh Hoa coal field(North-East of Viet Nam) were analyzed using Landsat time-series data during the 2008-2016 period. Based on land surface temperatures retrieved from Landsat thermal data, underground coal fires related to thermal anomalies were identified using the MEDIAN+1.5×IQR(IQR: Interquartile range) threshold technique. The locations of underground coal fires were validated using a coal fire map produced by the field survey data and cross-validated using the daytime ASTER thermal infrared imagery. Based on the fires extracted from seven Landsat thermal imageries, the spatiotemporal changes of underground coal fire areas were analyzed. The results showed that the thermalanomalous zones have been correlated with known coal fires. Cross-validation of coal fires using ASTER TIR data showed a high consistency of 79.3%. The largest coal fire area of 184.6 hectares was detected in 2010, followed by 2014(181.1 hectares) and 2016(178.5 hectares). The smaller coal fire areas were extracted with areas of 133.6 and 152.5 hectares in 2011 and 2009 respectively. Underground coal fires were mainly detected in the northern and southern part, and tend to spread to north-west of the coal field.
文摘The mineralogy and geochemistry data are presented for thirty-seven shales, four concretions, two carbonate sediments and seven lignites from the Marathousa coal field of the Megalopolis Basin in Greece. The argillaceous rocks consist of chlorite, illite, kaolinite, albite,quartz, opal-A, calcite and dolomite; the concretions of aragonite, gypsum and pyrite; and the carbonate rocks of calcite, quartz and illite. The mineral matter in the lignites consists of gyp-sum, quartz, albite, chlorite, illite, opal-A, dolomite, pyrite, and rarely calcite and kaolinite.A three-factor model explains the total variation of major and trace elements in the argillaceous sediments. The first factor is an aluminosilicate factor and involves the following elements: Al,Si, Mg, Na, K, Ti, Mn, Nb, Y, Rb, Zn, Cu, Ni, Cr, Nd and V, associated with chlorite,albite and illite. The second factor involves the elements Ca, Sr, Ba, Zn and Sc and is related to carbonate lithology and mainly the carbonate concretions with gypsum. The third factor in-volves Fe and Ce with a weak association with Mn. The diagenesis of the Marathousa sedi-ments and lignites was ot very advanced as indicated by (a) the total thickness of the sequence (500 m), (b) the presence of biogenic silica (opal-A) and (c) the age of the deposit (Pleis-tocene). For these reasons the presence of chlorite, illite and kaolinite in the sediments and lig-nite is due not to diagenetic reactions but to weathering of the flysch and metamorphic rocks at the edges of the Megalopolis Basin and transport of the weathering products (illite, chlorite,kaolinite) into the basin of deposition. The diagenetic minerals of the Marathousa sequence in-clude pyrite, gypsum, dolomite and aragonite.
文摘Taking the return air roadway of Tashan 8204 isolated island working face as the background, the evolution law of the stress field in the surrounding rock of the widened coal pillar area roadway during the mining period of the isolated island working face is obtained through numerical simulation. The hazardous area of strong mine pressure under different coal pillar widths is determined. Through simulation, it is known that when the width of the coal pillar is less than 20 m, there is large bearing capacity on the coal side of the roadway entity. The force on the side of the coal pillar is relatively small. When the width of the coal pillar ranges from 25 m to 45 m, the vertical stress on the roadway and surrounding areas is relatively high. Pressure relief measures need to be taken during mining to reduce surrounding rock stress. When the width of the coal pillar is greater than 45 m, the peak stress of the coal pillar is located in the deep part of the surrounding rock, but it still has a certain impact on the roadway. It is necessary to take pressure relief measures to transfer the stress to a deeper depth to ensure the stability of the triangular coal pillar during the safe mining period of the working face. This provides guidance for ensuring the stability of the triangular coal pillar during the safe mining period of the working face.
基金supported by a grant from the Major State Basic Research and Development Program of China (No. 2007CB714102)sponsored by the Fundamental Research Funds for the Central Universities (No. 2009B00714)
文摘The exact shape and size of the gasification channel during underground coal gasification(UGC) are of vital importance for the safety and stability of the upper parts of the geological formation.In practice existing geological measurements are insufficient to obtain such information because the coal seam is typically deeply buried and the geological conditions are often complex.This paper introduces a cylindrical model for the gasification channel.The rock and soil masses are assumed to be homogeneous and isotropic and the effect of seepage on the temperature field was neglected.The theory of heat conduction was used to write the equation predicting the temperature field around the gasification channel.The idea of an excess temperature was introduced to solve the equations.Applying this model to UCG in the field for an influence radius,r,of 70 m gave the model parameters,u1,2,3...,of 2.4,5.5,8.7...By adjusting the radius(2,4,or 6 m) reasonable temperatures of the gasification channel were found for 4 m.The temperature distribution in the vertical direction,and the combustion volume,were also calculated.Comparison to field measurements shows that the results obtained from the proposed model are very close to practice.
基金funding by the National Natural Science Foundation of China (No. 51574279)Outstanding Youth Science Foundation of Chongqing China (No. cstc2013jcyjjq90001)Open project by State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing University (No. 2011DA105287-FW201302)
文摘Spontaneous combustion of coal seam has been and continues to be a big problem in coal mines. It could pose great threat to the safety of the whole mine and all miners, especially when it occurs in or nearby coal mines. Besides, environment of area surrounded mines during combustion can be threatened where large amount of toxic gases including CO_2, CO, SO_2 and H_2S can be leased by fire in mine. Hence, it is important and significant for scholars to study the controlling and preventing of the coal seam fire. In this paper, the complicated reasons for the occurrence and development of spontaneous combustion in coal seam are analysed and different models under various air leakage situations are built as well. Based on the model and approximately calculation, the difficulty of fire extinguishment in coal seam is pointed out as the difficulty and poor effect to remove the large amount of heat released. Detailed measurements about backfilling and case analyses are also provided on the basis of the recent ten years' practice of controlling spontaneous combustion in coal seams in China. A technical fire prevention and control method has been concluded as five steps including detection, prevention, sealing, injection and pressure adjustment. However, various backfill materials require different application and environmental factors, so in this paper, analyses and discussion about the effect and engineering application of prevention of spontaneous combustion are provided according to different backfilling technologies and methods. Once the aforementioned fire prevention can be widely applied and regulated in mines, green mining will be achievable concerning mine fire prevention and control.
文摘Two design axioms and axiomatic approach were discussed. As an example of application, design process of a new style single prop was illustrated in term of axi- oms.
文摘A local thermal stress model of water-cooled-wall pulverized-coal gasifier was built, and ANSYS was used to simulate the stress field in the gasifier operation to research the damage of refractories and slag layer caused by the thermal stress. The results reveal that:(1) the maximum stress of water-cooled-wall gasifier appears at the interface between anchor nails and refractories as well as the interface between refractories and the slag layer, and the maximum stress of slag layer appears on the surface of the slag layer;(2) the increase of slag layer thickness can significantly reduce the thermal stress at the interface between anchor nails and refractories, but increase the thermal stress between slag layer and refractories;(3) when the therma I conductivity is 2-6 W · m-1 · K-1, the thermal stress increases rapidly with the increase of the thermal conductivity, but when the thermal conductivity is 6-10 W · m-1 · K-1, the thermal stress is basically stable;(4) the higher the cooling rate, the faster the decreasing speed of the temperature and thermal stress.
基金financially supported by the State Key Research Development Program of China(Grant No.2016YFC0600701)the National Natural Science Foundation of China(Grant No.51674170)
文摘In this study, the spatial distributions of stress and fracture fields for three typical underground coal mining layouts, Le, non-pillar mining (NM), top-coal caving mining (TCM) and protective coal-seam mining (PCM), are modeled using discrete element software UDEC, The numerical results show that different mining layouts can lead to different mining-induced stress fields, resulting in diverse fracture fields, For the PCM, the mining influenced area in front of the mining faces is the largest, and the stress concentration factor in front of the mining faces is the lowest, The spatial shapes of the mining-induced fracture fields under NM, TCM and PCM differ, and they are characterized by trapezoidal, triangular and tower shapes, respectively, The fractal dimensions of mining-induced fractures of the three mining layouts decrease in the order of PCM, TCM and NM, It is also shown that the PCM can result in a better gas control effect in coal mines with high outburst potential, The numerical results are expected to provide a basis for understanding of mining-induced gas seepage fields and provide a reference for high- efficiency coal mining,
基金financially supported by the National Natural Science Foundation of China (Nos.41402138, 41330635, and 41272154)Key Laboratory of Coal-based CO2 Capture and Geological Storage, Jiangsu Province (China University of Mining and Technology) (No.2016B04)
文摘Study on tectonic fractures based on the inversion of tectonic stress fields is an effective method. In this study, a geological model was set up based on geological data from the Hudi Coal Mine, Qinshui Basin, a mechanical model was established under the condition of rock mechanics and geostress, and the finite element method was used to simulate the paleotectonic stress field. Based on the Griffith and Mohr-Coulomb criterion, the distribution of tectonic fractures in the Shanxi Formation during the Indosinian, Yanshanian, and Himalayan period can be predicted with the index of comprehensive rupture rate. The results show that the acting force of the Pacific Plate and the India Plate to the North China Plate formed the direction of principal stress is N-S, NW - SE, and NE - SW, respectively, in different periods in the study area. Changes in the direction and strength of the acting force led to the regional gradients of tectonic stress magnitude, which resulted in an asymmetrical distribution state of the stress conditions in different periods. It is suggested that the low-stress areas are mainly located in the fault zones and extend along the direction of the fault zones. Furthermore, the high-stress areas are located in the junction of fold belts and the binding site of multiple folds. The development of tectonic fractures was affected by the distribution of stress intensity and the tectonic position of folds and faults, which resulted in some developed areas with level I and II. There are obvious differences in the development of tectonic fractures in the fold and fault zones and the anticline and syncline structure at the same fold zones. The tectonic fractures of the Shanxi Formation during the Himalayan period are more developed than those during the Indosinian and Yanshanian period due to the superposition of the late tectonic movement to the early tectonic movement and the differences in the magnitude and direction of stress intensity.
文摘A brief account of the development of the research on mining earthquakes and the general situation of the Mentougou Coal Mine medium scale experiment field for earthquake prediction and the project of monitor and prediction is given. The differences of waveforms between mining earthquakes and natural earthquakes is discussed. The magnitude frequency distribution of the 79 000 mining earthquakes of over M L1.0 from 1984 to 1995 is summarized . Finally, taking PH and PV, the principal compressive stress components of the focal mechanism of the mining earthquakes, as the criteria, analyses the stress background of the 12 large mining earthquakes.