This paper presents a new method for the correct selection of mining methods and pre-diction of main technological and economic indexes of the face in the gentle inclined thick seams with the application of the artifi...This paper presents a new method for the correct selection of mining methods and pre-diction of main technological and economic indexes of the face in the gentle inclined thick seams with the application of the artificial neural network theory and the expert system. The theory anal- ysis and calculating results indicate that the method is reliable, practical and precise. This method has strongly capabilities of self-study and non-linear dynamic data process. It is expected to be widely applied in the policy decision and prediction of mining technology in coal mine.展开更多
Explaining fundamentals of application of cable bolting for a thick seam depillaring,this paper summarizes the results of field studies conducted during adoption of this approach in more than fifteen panels of Madhusu...Explaining fundamentals of application of cable bolting for a thick seam depillaring,this paper summarizes the results of field studies conducted during adoption of this approach in more than fifteen panels of Madhusudanpur 7 pit and incline mine.Nearly 7.0 m thick Kajora top coal seam of this mine is developed on pillars along the floor horizon to an average height of 3.0 m,leaving a coal band of around 4.0 m along the roof.Analysis of procured core samples showed that roof strata are easily caveable with a caveability index value of around 2000 only.Easily caveable overlying strata and shallow depth of cover alleviated most of the expected strata mechanics problems of the thick seam mining.However,extraction of total thickness at shallow cover caused differential-subsidence and cracks on the surface.These manifestations were immediately tackled to avoid creation of a breathing path for spontaneous heating in the extracted area.展开更多
This paper analyzes the gas source of the horizontally sectioned fully mechanized caving face in the steeply inclined and extra-thick seam of Adaohai Coal Mine, and numerically simulates the stress distribution and pr...This paper analyzes the gas source of the horizontally sectioned fully mechanized caving face in the steeply inclined and extra-thick seam of Adaohai Coal Mine, and numerically simulates the stress distribution and pressure relief of the lower section coal after the upper section working face is mined. It theoretically analyzed the reasonable layout of the drainage boreholes, and designed the drainage borehole layout accordingly. In the upper and lower section of the working face, the actual drainage effect of the boreholes was inspected, and the air exhaust gas volume in the working face was statistically analyzed. It was confirmed that the layout of boreholes was reasonable, the gas control effect of working face was greatly improved and fully met the needs of safe mining. The control effect was greatly improved and the need for safe mining was fully met, and thus a gas drainage technology suitable for the coal seam storage conditions and mining technology of the Adaohai Coal Mine was found. That is to say: the gas emission from the working face of the section mining mainly comes from its lower coal body. Pre-draining the lower coal body of the section and depressurizing gas interception and drainage are the key to effectively solve the problem of gas emission from the working face. Drainage boreholes in the working face of the section should be arranged at high and low positions. The high-level boreholes are located about 2 m from the top of the working face, and the high-level boreholes are about 9 m away from the top of the working face. Through the pre drainage of high and low-level boreholes in advance and the interception and pressure relief drainage, the gas control in the horizontal sublevel fully mechanized caving mining face in steep and extra thick coal seam can realize a virtuous cycle.展开更多
To raise coal recovery ratio and solve the key problem of full-dimension mining, a new “3-section” technology of full-dimension mining is put forward in flat thick-seam according to the theory and mining practice. T...To raise coal recovery ratio and solve the key problem of full-dimension mining, a new “3-section” technology of full-dimension mining is put forward in flat thick-seam according to the theory and mining practice. This technology is proved to be rational and feasible in rodway layout system of stagger arrangement.展开更多
Cable truss systems have been widely applied in roadways with complicated conditions, such as the large cross-sections of deep wells, and high tectonic stress. However, they are rarely applied to roadways with extreme...Cable truss systems have been widely applied in roadways with complicated conditions, such as the large cross-sections of deep wells, and high tectonic stress. However, they are rarely applied to roadways with extremely thick coal seams because the control mechanism of the system for the deformation of the roof and the separation between coal rock segments is not completely understood. By using the relationship between the support system and the roof strata, a mechanical model was established to calculate the deformation of the roof in a thick coal seam with bedding separation under different support conditions: with an anchor truss support and without support. On this basis, the research was used to deduce a method for computing the minimum pre-tightening forces in the anchor truss, the maximum amounts of subsidence and separation with, and without, anchor truss support under the roof, and the maximum subsidence and the decreasing amounts of the separation before and after adopting the anchor truss. Additionally, mechanical relationships between the minimum pre-tightening force and the anchoring force in the anchor were analyzed. By taking a typical roadway with thick coal roof as an example, the theoretical results mentioned above were applied in the analysis and testing of a roof supporting project in a roadway field to verify the accuracy of the theory: favorable experimental results were achieved. In addition, the relationships among other parameters were analyzed, including the minimum pre-tightening forces applied by the anchor truss, the angle of inclination of the anchor cable, and the array pitch. Meanwhile, the changing characteristics of the amounts of roof separation and subsidence with key parameters of the support system(such as array pitch, pre-tightening force, and inclination angle) were also analyzed. The research results revealed the acting mechanism of the anchor truss in control of roadway stability with a thick coal seam, providing a theoretical basis of its application in coal mining.展开更多
Considering the danger of water inrush in mining very thick coal seam under water-rich roof in Majialiang Coal Mine,the universal discrete element(UDEC)software was used to simulate the overburden fracture evolution l...Considering the danger of water inrush in mining very thick coal seam under water-rich roof in Majialiang Coal Mine,the universal discrete element(UDEC)software was used to simulate the overburden fracture evolution laws when mining 4#coal seam.Besides,this study researched on the influence of face advancing length,speed and mining height on the height of the water flowing fractured zones(HWFFZ),and analyzed the correlation of face advancing length and change rules of aquifer water levels and goaf water inflow.Based on those mentioned above,this research proposed the following water-controlling technologies:draining the roof water before mining,draining goaf water,reasonable advancing speed and mining thickness.These water-controlling technologies were successfully used in the feld,thus ensured safely mining the very thick coal seam under water-rich roof.展开更多
Accidents such as support failure and excessive deformation of roadways due to drastic changes in strata behaviors are frequently reported when mining the extra-thick coal seams Nos.3e5 in Datong coal mine with top-co...Accidents such as support failure and excessive deformation of roadways due to drastic changes in strata behaviors are frequently reported when mining the extra-thick coal seams Nos.3e5 in Datong coal mine with top-coal caving method,which significantly hampers the mine's normal production.To understand the mechanism of strata failure,this paper presented a structure evolution model with respect to strata behaviors.Then the behaviors of strata overlying the extra-thick coal seams were studied with the combined method of theoretical analysis,physical simulation,and field measurement.The results show that the key strata,which are usually thick-hard strata,play an important role in overlying movement and may influence the mining-induced strata behaviors in the working face using top-coal caving method.The structural model of far-field key strata presents a 'masonry beam' type structure when'horizontal O-X' breakage type happens.The rotational motion of the block imposed radial compressive stress on the surrounding rock mass of the roadway.This can induce excessive deformation of roadway near the goaf.Besides,this paper proposed a pre-control technology for the hard roof based on fracture holes and underground roof pre-splitting.It could effectively reduce stress concentration and release the accumulated energy of the strata,when mining underground coal resources with top-coal caving method.展开更多
The paper aims to identify a reasonable method for mining ultra-thick coal seams in an end-slope in surface mine, With a case study of Heidaigou surface coal mine(HSCM), the paper conducted a comparative research on t...The paper aims to identify a reasonable method for mining ultra-thick coal seams in an end-slope in surface mine, With a case study of Heidaigou surface coal mine(HSCM), the paper conducted a comparative research on three mining methods, namely Underground Mining Method(UMM), Highwall Mining System(HMS) and Local Steep Slope Mining Method(LSSMM). A model was firstly established to simulate the impact that UMM and HMS exert on monitoring points and surface deformation. The way that stripping and excavation amount varies with different slope angle, and the corresponding end slope stability were analyzed in the mode of LSSMM. Then a TOPSIS model was established by taking into account six indicators such as recovery ratio, technical complexity and adaptability, the impact on surface mining production, production safety and economic benefits. Finally, LSSMM was determined as the best mining method for mining ultra-thick coal seams in end slope in HSCM.展开更多
It is important to study the mining technology under structures for raising the coal resources recovery ratio. Based on the geological and mining conditions, the top coal caving harmonic mining technique in thick coal...It is important to study the mining technology under structures for raising the coal resources recovery ratio. Based on the geological and mining conditions, the top coal caving harmonic mining technique in thick coal seam beneath the earth dam was put forward and studied. The 5 factors such as the panel mining direction, panel size, panel location, panel mining sequence and panel advance velocity were taken into account in this technique. The dam movement and deformation were predicted after the thick coal seam mining and the effects of mining on the dam were studied. By setting up the surveying stations on the dam, the movement and deformation of the dam were observed during mining. By taking some protective measures on the dam, the top coal caving mining technique in thick coal seam beneath the earth dam was carried out successfully. The study demonstrates that harmonic mining in thick coal seam is feasible under the dam. The safety of the earth dam after mining was ensured and the coal resources recovery ratio was improved.展开更多
The EGAT Mae Moh Mine is the largest open pit lignite mine in Thailand and it produces lignite about 16 million tons annually. In the near future, the pit limit of the mine will be reached and underground mine will th...The EGAT Mae Moh Mine is the largest open pit lignite mine in Thailand and it produces lignite about 16 million tons annually. In the near future, the pit limit of the mine will be reached and underground mine will then be developed through the open pit in the depth of 400 - 600 m from the surface. However, due to the challenges for underground mining such as poor geological conditions, extra thickness (20 - 30 m) of coal seams, and weak mechanical properties of coal seams and the surrounding rock, the success possibility of underground mining and an applicable underground mining method is being investigated at the present. The paper discusses the applicability of multi-slice bord-and-pillar method for the soft extra thick coal seams in the Mae Moh mine by means of numerical analyses using the 3D finite difference code “FLAC3D”.展开更多
The application of light hydraulic support highlights the advantages of longwall top-coal caving (LTC) in thinner thick-seams (3. 0~ 5. 0 m). Considering the problems in practice, the developing of its new series will...The application of light hydraulic support highlights the advantages of longwall top-coal caving (LTC) in thinner thick-seams (3. 0~ 5. 0 m). Considering the problems in practice, the developing of its new series will promote the mining of LTC with light hydraulic supports. Some relevant technical problems of the caving technology and the future of this series of supports are analyzed in this paper with several new opinions.展开更多
In order to clarify the danger of water breakout in the bottom plate of extra-thick coal seam mining, 2202 working face of a mine in the west is taken as the research object, and it is proposed to use the on-site moni...In order to clarify the danger of water breakout in the bottom plate of extra-thick coal seam mining, 2202 working face of a mine in the west is taken as the research object, and it is proposed to use the on-site monitoring means combining borehole peeping and microseismic monitoring, combined with the theoretical analysis to analyze the danger of water breakout in the bottom plate. The results show that: 1) the theoretically calculated maximum damage depth of the bottom plate is 27.5 m, and its layer is located above the Austrian ash aquifer, which has the danger of water breakout;2) the drill hole peeping at the bottom plate of the working face shows that the depth of the bottom plate fissure development reaches 26 m, and the integrity of the water barrier layer has been damaged, so there is the risk of water breakout;3) for the microseismic monitoring of the anomalous area, the bottom plate of the return air downstream channel occurs in the field with a one-week lag, which shows that microseismic monitoring events may reflect the water breakout of the underground. This shows that the microseismic monitoring events can reflect the changes of the underground flow field, which can provide a reference basis for the early warning of water breakout. The research results can provide reference for the prediction of sudden water hazard.展开更多
文摘This paper presents a new method for the correct selection of mining methods and pre-diction of main technological and economic indexes of the face in the gentle inclined thick seams with the application of the artificial neural network theory and the expert system. The theory anal- ysis and calculating results indicate that the method is reliable, practical and precise. This method has strongly capabilities of self-study and non-linear dynamic data process. It is expected to be widely applied in the policy decision and prediction of mining technology in coal mine.
基金sponsored by the general manager,Kajora Area of Eastern Coalfield Limited(ECL).Co-operation of general manager of the Area,project officer,Madhusudanpur 7 Pit and Incline Colliery,manager and safety officer,Madhusudanpur 7 Pit and Incline Colliery in conducting this study is thankfully acknowledged
文摘Explaining fundamentals of application of cable bolting for a thick seam depillaring,this paper summarizes the results of field studies conducted during adoption of this approach in more than fifteen panels of Madhusudanpur 7 pit and incline mine.Nearly 7.0 m thick Kajora top coal seam of this mine is developed on pillars along the floor horizon to an average height of 3.0 m,leaving a coal band of around 4.0 m along the roof.Analysis of procured core samples showed that roof strata are easily caveable with a caveability index value of around 2000 only.Easily caveable overlying strata and shallow depth of cover alleviated most of the expected strata mechanics problems of the thick seam mining.However,extraction of total thickness at shallow cover caused differential-subsidence and cracks on the surface.These manifestations were immediately tackled to avoid creation of a breathing path for spontaneous heating in the extracted area.
文摘This paper analyzes the gas source of the horizontally sectioned fully mechanized caving face in the steeply inclined and extra-thick seam of Adaohai Coal Mine, and numerically simulates the stress distribution and pressure relief of the lower section coal after the upper section working face is mined. It theoretically analyzed the reasonable layout of the drainage boreholes, and designed the drainage borehole layout accordingly. In the upper and lower section of the working face, the actual drainage effect of the boreholes was inspected, and the air exhaust gas volume in the working face was statistically analyzed. It was confirmed that the layout of boreholes was reasonable, the gas control effect of working face was greatly improved and fully met the needs of safe mining. The control effect was greatly improved and the need for safe mining was fully met, and thus a gas drainage technology suitable for the coal seam storage conditions and mining technology of the Adaohai Coal Mine was found. That is to say: the gas emission from the working face of the section mining mainly comes from its lower coal body. Pre-draining the lower coal body of the section and depressurizing gas interception and drainage are the key to effectively solve the problem of gas emission from the working face. Drainage boreholes in the working face of the section should be arranged at high and low positions. The high-level boreholes are located about 2 m from the top of the working face, and the high-level boreholes are about 9 m away from the top of the working face. Through the pre drainage of high and low-level boreholes in advance and the interception and pressure relief drainage, the gas control in the horizontal sublevel fully mechanized caving mining face in steep and extra thick coal seam can realize a virtuous cycle.
基金The National Important Technique Innovation Item ( No.[2 0 0 1] 44 1)
文摘To raise coal recovery ratio and solve the key problem of full-dimension mining, a new “3-section” technology of full-dimension mining is put forward in flat thick-seam according to the theory and mining practice. This technology is proved to be rational and feasible in rodway layout system of stagger arrangement.
基金Project(51404248)supported by the National Natural Science Foundation of the Youth Science Foundation of ChinaProject(2017XKQY012)supported by Fundamental Research Funds for the Central Universities of ChinaProject(2014M551702)supported by the China Postdoctoral Science Foundation
文摘Cable truss systems have been widely applied in roadways with complicated conditions, such as the large cross-sections of deep wells, and high tectonic stress. However, they are rarely applied to roadways with extremely thick coal seams because the control mechanism of the system for the deformation of the roof and the separation between coal rock segments is not completely understood. By using the relationship between the support system and the roof strata, a mechanical model was established to calculate the deformation of the roof in a thick coal seam with bedding separation under different support conditions: with an anchor truss support and without support. On this basis, the research was used to deduce a method for computing the minimum pre-tightening forces in the anchor truss, the maximum amounts of subsidence and separation with, and without, anchor truss support under the roof, and the maximum subsidence and the decreasing amounts of the separation before and after adopting the anchor truss. Additionally, mechanical relationships between the minimum pre-tightening force and the anchoring force in the anchor were analyzed. By taking a typical roadway with thick coal roof as an example, the theoretical results mentioned above were applied in the analysis and testing of a roof supporting project in a roadway field to verify the accuracy of the theory: favorable experimental results were achieved. In addition, the relationships among other parameters were analyzed, including the minimum pre-tightening forces applied by the anchor truss, the angle of inclination of the anchor cable, and the array pitch. Meanwhile, the changing characteristics of the amounts of roof separation and subsidence with key parameters of the support system(such as array pitch, pre-tightening force, and inclination angle) were also analyzed. The research results revealed the acting mechanism of the anchor truss in control of roadway stability with a thick coal seam, providing a theoretical basis of its application in coal mining.
基金provided by the Priority Academic Program Development of Jiangsu Higher Education Institutions of China(No.SZBF2011-6-B35)the Fundamental Research Funds for the Central Universities of China(No.2012LWB42)
文摘Considering the danger of water inrush in mining very thick coal seam under water-rich roof in Majialiang Coal Mine,the universal discrete element(UDEC)software was used to simulate the overburden fracture evolution laws when mining 4#coal seam.Besides,this study researched on the influence of face advancing length,speed and mining height on the height of the water flowing fractured zones(HWFFZ),and analyzed the correlation of face advancing length and change rules of aquifer water levels and goaf water inflow.Based on those mentioned above,this research proposed the following water-controlling technologies:draining the roof water before mining,draining goaf water,reasonable advancing speed and mining thickness.These water-controlling technologies were successfully used in the feld,thus ensured safely mining the very thick coal seam under water-rich roof.
基金supported by the Special Funding Projects of“Sanjin Scholars”Supporting Plan(Grant No.2050205)
文摘Accidents such as support failure and excessive deformation of roadways due to drastic changes in strata behaviors are frequently reported when mining the extra-thick coal seams Nos.3e5 in Datong coal mine with top-coal caving method,which significantly hampers the mine's normal production.To understand the mechanism of strata failure,this paper presented a structure evolution model with respect to strata behaviors.Then the behaviors of strata overlying the extra-thick coal seams were studied with the combined method of theoretical analysis,physical simulation,and field measurement.The results show that the key strata,which are usually thick-hard strata,play an important role in overlying movement and may influence the mining-induced strata behaviors in the working face using top-coal caving method.The structural model of far-field key strata presents a 'masonry beam' type structure when'horizontal O-X' breakage type happens.The rotational motion of the block imposed radial compressive stress on the surrounding rock mass of the roadway.This can induce excessive deformation of roadway near the goaf.Besides,this paper proposed a pre-control technology for the hard roof based on fracture holes and underground roof pre-splitting.It could effectively reduce stress concentration and release the accumulated energy of the strata,when mining underground coal resources with top-coal caving method.
基金provided by the National Natural Science Foundation of China(No.90510002)the Science and Technology Research of the Ministry of Education of China(No.306008)
文摘The paper aims to identify a reasonable method for mining ultra-thick coal seams in an end-slope in surface mine, With a case study of Heidaigou surface coal mine(HSCM), the paper conducted a comparative research on three mining methods, namely Underground Mining Method(UMM), Highwall Mining System(HMS) and Local Steep Slope Mining Method(LSSMM). A model was firstly established to simulate the impact that UMM and HMS exert on monitoring points and surface deformation. The way that stripping and excavation amount varies with different slope angle, and the corresponding end slope stability were analyzed in the mode of LSSMM. Then a TOPSIS model was established by taking into account six indicators such as recovery ratio, technical complexity and adaptability, the impact on surface mining production, production safety and economic benefits. Finally, LSSMM was determined as the best mining method for mining ultra-thick coal seams in end slope in HSCM.
基金sponsored by the National Natural Science Foundation of China(No.51374092)
文摘It is important to study the mining technology under structures for raising the coal resources recovery ratio. Based on the geological and mining conditions, the top coal caving harmonic mining technique in thick coal seam beneath the earth dam was put forward and studied. The 5 factors such as the panel mining direction, panel size, panel location, panel mining sequence and panel advance velocity were taken into account in this technique. The dam movement and deformation were predicted after the thick coal seam mining and the effects of mining on the dam were studied. By setting up the surveying stations on the dam, the movement and deformation of the dam were observed during mining. By taking some protective measures on the dam, the top coal caving mining technique in thick coal seam beneath the earth dam was carried out successfully. The study demonstrates that harmonic mining in thick coal seam is feasible under the dam. The safety of the earth dam after mining was ensured and the coal resources recovery ratio was improved.
文摘The EGAT Mae Moh Mine is the largest open pit lignite mine in Thailand and it produces lignite about 16 million tons annually. In the near future, the pit limit of the mine will be reached and underground mine will then be developed through the open pit in the depth of 400 - 600 m from the surface. However, due to the challenges for underground mining such as poor geological conditions, extra thickness (20 - 30 m) of coal seams, and weak mechanical properties of coal seams and the surrounding rock, the success possibility of underground mining and an applicable underground mining method is being investigated at the present. The paper discusses the applicability of multi-slice bord-and-pillar method for the soft extra thick coal seams in the Mae Moh mine by means of numerical analyses using the 3D finite difference code “FLAC3D”.
文摘The application of light hydraulic support highlights the advantages of longwall top-coal caving (LTC) in thinner thick-seams (3. 0~ 5. 0 m). Considering the problems in practice, the developing of its new series will promote the mining of LTC with light hydraulic supports. Some relevant technical problems of the caving technology and the future of this series of supports are analyzed in this paper with several new opinions.
文摘In order to clarify the danger of water breakout in the bottom plate of extra-thick coal seam mining, 2202 working face of a mine in the west is taken as the research object, and it is proposed to use the on-site monitoring means combining borehole peeping and microseismic monitoring, combined with the theoretical analysis to analyze the danger of water breakout in the bottom plate. The results show that: 1) the theoretically calculated maximum damage depth of the bottom plate is 27.5 m, and its layer is located above the Austrian ash aquifer, which has the danger of water breakout;2) the drill hole peeping at the bottom plate of the working face shows that the depth of the bottom plate fissure development reaches 26 m, and the integrity of the water barrier layer has been damaged, so there is the risk of water breakout;3) for the microseismic monitoring of the anomalous area, the bottom plate of the return air downstream channel occurs in the field with a one-week lag, which shows that microseismic monitoring events may reflect the water breakout of the underground. This shows that the microseismic monitoring events can reflect the changes of the underground flow field, which can provide a reference basis for the early warning of water breakout. The research results can provide reference for the prediction of sudden water hazard.
