About 75% water-inrush accidents in China are caused by geological structure such as faults, therefore, it is necessary to investigate the water-inrush mechanism of faults to provide references for the mining activity...About 75% water-inrush accidents in China are caused by geological structure such as faults, therefore, it is necessary to investigate the water-inrush mechanism of faults to provide references for the mining activity above confined water. In this paper, based on the fluid-solid coupling theory, we built the stress-seepage coupling model for rock, then we combined with an example of water-inrush caused by fault, studied the water-inrush mechanism by using the numerical software COMSOL Mutiphysics, analyzed the change rule of shear stress, vertical stress, plastic area and water pressure for stope with a fault, and estimated the water-inrush risk at the different distances between working faces and the fault. The numerical simula- tion results indicate that： （1） the water-inrush risk will grow as the decrease of the distance between working face and the fault; （2） the failure mode of the rock in floor with fault is shear failure; （3） the rock between water-containing fault and working face failure is the reason for water-inrush.展开更多
The drum shearer and high pressure water jet combined cutting system is an effective technology to cut hard coal-rock, but one problem of the technology is the choice of pick and nozzle location parameters. In order t...The drum shearer and high pressure water jet combined cutting system is an effective technology to cut hard coal-rock, but one problem of the technology is the choice of pick and nozzle location parameters. In order to solve the problem, the process and mechanism of combined cutting arc studied and mining seepage catastrophe theory is used to construct the mathematic and physical model of combined cutting hard coal-rock. Based on the model and detailed analysis of combined cutting mechanism, the single pick and nozzle combined cutting test-bed is built to test the main pick and nozzle location parameters of drum shearer and water jet combined cutting system. Test results show that the best vertical distance between the pick-tip and nozzle center point is the sum of cutting thickness and proper target distance in the Y axial direction; the best horizontal distance is the length between pick-tip point and coal-rock surface bursting crack point in the X axial direction. The best incident angle of water jet should be the same as the bursting crack line＇s angle in theory, but considering other important factors comprehensively, it is more reasonable when the incident angle of water jet is 90°.展开更多
The reliability and maintainability of electrical system of drum shearer at Parvade. 1 Coal Mine in central Iran was analyzed. The maintenance and failure data were collected during 19 months of shearer operation. Acc...The reliability and maintainability of electrical system of drum shearer at Parvade. 1 Coal Mine in central Iran was analyzed. The maintenance and failure data were collected during 19 months of shearer operation. According to trend and serial correlation tests, the data were independent and identically distributed （iid） and therefore the statistical techniques were used for modeling. The data analysis show that the time between failures （TBF） and time to repair （TTR） data obey the lognormal and Weibull 3 parameters distribution respectively. Reliability-based preventive maintenance time intervals for electrical system of the drum shearer were calculated with regard to reliability plot. The reliability-based maintenance intervals for 90%, 80%, 70% and 50% reliability level are respectively 9.91, 17.96, 27.56 and 56.1 h. Also the calculations show that time to repair （TTR） of this system varies in range 0.17-4 h with 1.002 h as mean time to repair （MTTR）. There is a 80% chance that the electrical system of shearer of Parvade. 1 mine repair will be accomplished within 1.45 h.展开更多
Phreatic water resources are widely found in thick unconsolidated surface layers in western China, where water levels respond sensitively and quickly to large-scale underground mining in conjunction with shallow coal ...Phreatic water resources are widely found in thick unconsolidated surface layers in western China, where water levels respond sensitively and quickly to large-scale underground mining in conjunction with shallow coal seams. Longwall face #32201 of the Bulianta Coal Mine, in the Shendong coalfield was selected as an industrial trail base, where field observations on ground-water levels were conducted when the working face was below a water-rich area. The space-time variation in the behavior of un-consolidated water levels in response to underground mining and its relation with of advance were observed through the field trials. The basic conditions for water preservation in mines are presented and the mechanisms of water preservation in mining analyzed, given the geological condition of two key strata and a severely weathered layer buried in the overburden. The field trails show that water preservation in mining shallow coal seams can be successful under suitable conditions, providing new technology for envi-ronmental protection in the desert coalfields of northwestern China.展开更多
The deposit scale in the coal mine shaft usually causes serious accidents, such as making rope broken, cage seized or dropped. To solve this kind of problems, the re-search of the cutting scale mechanism was made, and...The deposit scale in the coal mine shaft usually causes serious accidents, such as making rope broken, cage seized or dropped. To solve this kind of problems, the re-search of the cutting scale mechanism was made, and a new type of removal scale equipment was made with using imported hard alloy material. The cutting experiment and actual cutting show that it can adapt to abominable condition in the shaft, such as narrow space, wet and excessive shaft crevice water and so on, and can work safely and reliably, and has high cutting scale efficiency. It can also cut out the deposit scale in the circular section of shaft.展开更多
Analyzed the rule of the Water Flowing Fractured (WFF) zone's development during the fully mechanized top coal caving.Six influence factors of WFF's height were selected,viz.mining thickness,base rock thicknes...Analyzed the rule of the Water Flowing Fractured (WFF) zone's development during the fully mechanized top coal caving.Six influence factors of WFF's height were selected,viz.mining thickness,base rock thickness,dip angle,uniaxial compressing strength of roof,mudstone proportion in overlying rock,and structure of overlying rock. The height-forecasting model of WFF was established based on the Artificial Neural Net-work techniques,and was applied in the first fully mechanized top coal caving face under sea in China.展开更多
The purpose of this paper is to clarify how the Kabu-ido system can be employed to successfully regulate groundwater pumping. This was accomplished by analyzing surviving historical documents, including budgetary note...The purpose of this paper is to clarify how the Kabu-ido system can be employed to successfully regulate groundwater pumping. This was accomplished by analyzing surviving historical documents, including budgetary notes and a diary. The Kabu-ido system was a customary institution for groundwater management in a ring levee area of the Noubi Plain in Japan that consisted of three programs： restriction of groundwater pumping through a permit system, groundwater pricing and economic compensation. The system was created in the 1810s and survived for 100 years. This paper covers the Kabu-ido system from the 1810s to the 1860s, the first half of the 100-year history. Excessive groundwater pumping is not a new environmental problem. Although many case studies have investigated remedial actions, few have investigated how local residents addressed the problem before the 20th century because of a lack of documents. The Kabu-ido system is an exception in which of the procedure was documented in writing. The historical data indicate that it was a pioneering institution for groundwater management.展开更多
基金Supported by the National Basic Research Program of China （2010CB226800） the National Natural Science Foundation of China （50904065） the Program for New Century Excellent Talents in University （NCET-09-0728）
文摘About 75% water-inrush accidents in China are caused by geological structure such as faults, therefore, it is necessary to investigate the water-inrush mechanism of faults to provide references for the mining activity above confined water. In this paper, based on the fluid-solid coupling theory, we built the stress-seepage coupling model for rock, then we combined with an example of water-inrush caused by fault, studied the water-inrush mechanism by using the numerical software COMSOL Mutiphysics, analyzed the change rule of shear stress, vertical stress, plastic area and water pressure for stope with a fault, and estimated the water-inrush risk at the different distances between working faces and the fault. The numerical simula- tion results indicate that： （1） the water-inrush risk will grow as the decrease of the distance between working face and the fault; （2） the failure mode of the rock in floor with fault is shear failure; （3） the rock between water-containing fault and working face failure is the reason for water-inrush.
基金Project(2012AA062104) supported by the National High Technology Research and Development Program of ChinaProject(201104583) supported by the Postdoctoral Special Funded Projects,China
文摘The drum shearer and high pressure water jet combined cutting system is an effective technology to cut hard coal-rock, but one problem of the technology is the choice of pick and nozzle location parameters. In order to solve the problem, the process and mechanism of combined cutting arc studied and mining seepage catastrophe theory is used to construct the mathematic and physical model of combined cutting hard coal-rock. Based on the model and detailed analysis of combined cutting mechanism, the single pick and nozzle combined cutting test-bed is built to test the main pick and nozzle location parameters of drum shearer and water jet combined cutting system. Test results show that the best vertical distance between the pick-tip and nozzle center point is the sum of cutting thickness and proper target distance in the Y axial direction; the best horizontal distance is the length between pick-tip point and coal-rock surface bursting crack point in the X axial direction. The best incident angle of water jet should be the same as the bursting crack line＇s angle in theory, but considering other important factors comprehensively, it is more reasonable when the incident angle of water jet is 90°.
文摘The reliability and maintainability of electrical system of drum shearer at Parvade. 1 Coal Mine in central Iran was analyzed. The maintenance and failure data were collected during 19 months of shearer operation. According to trend and serial correlation tests, the data were independent and identically distributed （iid） and therefore the statistical techniques were used for modeling. The data analysis show that the time between failures （TBF） and time to repair （TTR） data obey the lognormal and Weibull 3 parameters distribution respectively. Reliability-based preventive maintenance time intervals for electrical system of the drum shearer were calculated with regard to reliability plot. The reliability-based maintenance intervals for 90%, 80%, 70% and 50% reliability level are respectively 9.91, 17.96, 27.56 and 56.1 h. Also the calculations show that time to repair （TTR） of this system varies in range 0.17-4 h with 1.002 h as mean time to repair （MTTR）. There is a 80% chance that the electrical system of shearer of Parvade. 1 mine repair will be accomplished within 1.45 h.
基金supports for this work provided by the Research Fund of the State Key Laboratory of Coal Resources and Mine Safety (NoSKLCRSM08X2)the Jiangsu "333" High Qualified Talents, the National Natural Science Foundation of China (No50904063)the Scientific Research Foundation of China University of Mining & Technology (Nos.2008A003 and 2009A001)
文摘Phreatic water resources are widely found in thick unconsolidated surface layers in western China, where water levels respond sensitively and quickly to large-scale underground mining in conjunction with shallow coal seams. Longwall face #32201 of the Bulianta Coal Mine, in the Shendong coalfield was selected as an industrial trail base, where field observations on ground-water levels were conducted when the working face was below a water-rich area. The space-time variation in the behavior of un-consolidated water levels in response to underground mining and its relation with of advance were observed through the field trials. The basic conditions for water preservation in mines are presented and the mechanisms of water preservation in mining analyzed, given the geological condition of two key strata and a severely weathered layer buried in the overburden. The field trails show that water preservation in mining shallow coal seams can be successful under suitable conditions, providing new technology for envi-ronmental protection in the desert coalfields of northwestern China.
文摘The deposit scale in the coal mine shaft usually causes serious accidents, such as making rope broken, cage seized or dropped. To solve this kind of problems, the re-search of the cutting scale mechanism was made, and a new type of removal scale equipment was made with using imported hard alloy material. The cutting experiment and actual cutting show that it can adapt to abominable condition in the shaft, such as narrow space, wet and excessive shaft crevice water and so on, and can work safely and reliably, and has high cutting scale efficiency. It can also cut out the deposit scale in the circular section of shaft.
基金National Science Support Plan of China(2006BAB16B04)
文摘Analyzed the rule of the Water Flowing Fractured (WFF) zone's development during the fully mechanized top coal caving.Six influence factors of WFF's height were selected,viz.mining thickness,base rock thickness,dip angle,uniaxial compressing strength of roof,mudstone proportion in overlying rock,and structure of overlying rock. The height-forecasting model of WFF was established based on the Artificial Neural Net-work techniques,and was applied in the first fully mechanized top coal caving face under sea in China.
文摘The purpose of this paper is to clarify how the Kabu-ido system can be employed to successfully regulate groundwater pumping. This was accomplished by analyzing surviving historical documents, including budgetary notes and a diary. The Kabu-ido system was a customary institution for groundwater management in a ring levee area of the Noubi Plain in Japan that consisted of three programs： restriction of groundwater pumping through a permit system, groundwater pricing and economic compensation. The system was created in the 1810s and survived for 100 years. This paper covers the Kabu-ido system from the 1810s to the 1860s, the first half of the 100-year history. Excessive groundwater pumping is not a new environmental problem. Although many case studies have investigated remedial actions, few have investigated how local residents addressed the problem before the 20th century because of a lack of documents. The Kabu-ido system is an exception in which of the procedure was documented in writing. The historical data indicate that it was a pioneering institution for groundwater management.
