With an increase of mining the upper limits under unconsolidated aquifers, dewatering of the bottom aquifer of the Quaternary system has become a major method to avoid water and sand inrushes.In the 8th District of th...With an increase of mining the upper limits under unconsolidated aquifers, dewatering of the bottom aquifer of the Quaternary system has become a major method to avoid water and sand inrushes.In the 8th District of the Taiping Coal Mine in south-western Shandong province, the bottom aquifer of the Quaternary system is moderate to excellent in water-yielding capacity.The base rock above the coal seam is very thin in the concealed coal field of the Carboniferous and Permian systems.Therefore, a comprehensive dewatering plan from both the ground surface and the panel was proposed to lower the groundwater level in order to ensure mining safety.According to the hydrogeologic conditions of the 8th District, we established a numerical model so that we could simulate the groundwater flow in the dewatering process.We obtained the simulation parameters from previous data using backward modeling, such as the average coefficient of permeability of 12 m/d and the elastic storage coefficient of 0.002.From the same model, we predicted the movement of groundwater and water level variables and obtained the visible effect of the dewatering project.Despite the overburden failure during mining, no water and/or sand inrush occurred because the groundwater level in the bottom aquifer was lowered to a safe water level.展开更多
As a unique low-temperature water mass in Antarctic coastal region, the Ice Shelf Water (ISW) is an important component for the formation of the Antarctic Bottom Water (AABW). In this paper, we present a criterion for...As a unique low-temperature water mass in Antarctic coastal region, the Ice Shelf Water (ISW) is an important component for the formation of the Antarctic Bottom Water (AABW). In this paper, we present a criterion for ISW identification based on freezing point at the sea surface, and we study spatial distribution of ISW in front of the Amery Ice Shelf (AIS) and its flow path in Prydz Bay by analyzing hydrographic data from Australian cruises in 2001 and 2002, as well as Chinese cruises in 2003, 2005, 2006, and 2008, all being made in the austral summer. The relatively cold and fresh ISW occurred as several discrete water blocks with cold cores in front of the AIS, within the depth range of 100?600 m, under the seasonal thermocline. ISW had obvious temporal and spatial variations and the spatial distribution pattern changed greatly after 2005. Most of ISW was concentrated west of 73°E during 2001 to 2003 and 2006, but it was widespread to east in 2005 and 2008. In all observation years, a small amount of cold ISW always occurs at the west end of the AIS front section, where the coldest ISW in the whole section also occurred in 2001, 2003 and 2006. Considering general cyclonic circulation pattern under the AIS, the ISW flowing out from west end of the AIS front might have experienced the longest cooling period under ice shelf, so it would have the lowest temperature. Analysis of data from meridian sections in Prydz Bay in 2003 implied that ISW in the west could spread north to the continental break along the east flank of the Fram Bank near 70.5°E, mix with the upwelling Circumpolar Deep Water and possibly contribute to the formation of AABW.展开更多
Serious shaft lining failures often occur when shaft linings are constructed by passing them through the deep topsoil of Quaternary strata. This approach also leads to the formation of an aquifer at the bottom.Based o...Serious shaft lining failures often occur when shaft linings are constructed by passing them through the deep topsoil of Quaternary strata. This approach also leads to the formation of an aquifer at the bottom.Based on the theory of the additional stress which is the main reason for these failures, this study focuses on the treatment effect of underground continuous impervious curtain(UCIC) in terms of different factors, namely, the location, shape, range, and width, by using numerical simulation. Results show that the UCIC can reduce the stress concentration in the shaft lining formed in the bottom aquifer. The UCIC can also reinforce the shaft lining at different angles and can be applied in actual situations. The strength factors of the inner surface of the shaft lining increase after the UCIC are used. The material strength and width of the UCIC show an obvious effect on the stability of the shaft lining. Results proved that the UCIC could effectively strengthen the stability of the shaft lining when it was built in the aquifer or built in the aquifer and above and below the layer.展开更多
The failure depth of the coal seam floor is one important consideration that must be kept in mind when mining is carried out above a confined aquifer.Determining the floor failure depth is the essential precondition f...The failure depth of the coal seam floor is one important consideration that must be kept in mind when mining is carried out above a confined aquifer.Determining the floor failure depth is the essential precondition for predicting the water-resisting ability of the floor.We have used a high-precision microseismic monitoring technique to overcome the limited amount of data available from field measurements. The failure depth of a coal seam floor,especially an inclined coal seam floor,may be more accurately estimated by monitoring the continuous,dynamic failure of the floor.The monitoring results indicate the failure depth of the coal seam floor near the workface conveyance roadway（the lower crossheading） is deeper and that the failure range is wider here compared to the coal seam floor near the return airway（the upper crossheading）.The results of micro-seismic monitoring show that the dangerous area for water-inrush from the coal seam floor may be identified.This provides an important field measurement that helps ensure safe and highly efficient mining of the inclined coal seam above the confined aquifer at the Taoyuan Coal Mine.展开更多
With the increase in mining depth many mining areas in China have entered a period necessitating mining above aquifers. Production safety in coal mines in northern China is under serious threat from Ordovician karst w...With the increase in mining depth many mining areas in China have entered a period necessitating mining above aquifers. Production safety in coal mines in northern China is under serious threat from Ordovician karst water on coal seam floors, in order to analyze the destruction of water-resisting strata in floors of coal seams being mined and to achieve safe mining above deep aquifers, we established a numerical model of water-resisting strata, considering the structural characteristics and mechanical properties of a floor layered with hard and soft rock. We simulated the distribution characteristics of deformation, failure and seepage using the analytical module of fluid-structure interaction of FLAt：. We also obtained the corresponding stress distribution, deformation and flow vectors. Our results indi- cate that： （1） the advance of the working face causes water-resisting strata in goaf floors to form a deep double-clamped beam, subject to homogeneous loading at the bottom; （2） the two sides of the rock beam are subject 1~0 shear failure; （3） both sides of the rock seam at the bottom of the water-resisting strata are subject to tension and the greater the working face advance, the more serious the failure; C4） the original balance of the stress and seepage fields are broken and redistributed due to mining activities, especially the interaction of the abutment pressure in both sides of the goal; the lateral pressure on the goal floor and the water pressure on the floor of the aquifer promote floor heave and shear failure on both sides of the floor, forming a water-inrush passage. Our study results can provide references for the mechanism of water-inrush on mine floors.展开更多
It is well-known that barriers have a significant impact on the production performance of horizontal wells developed in a bottom water drive reservoir. In most cases, reservoir barriers are semi-permeable. Based on pr...It is well-known that barriers have a significant impact on the production performance of horizontal wells developed in a bottom water drive reservoir. In most cases, reservoir barriers are semi-permeable. Based on previous research on impermeable reservoir barrier, a mathematical flow model was derived for a horizontal well of a bottom water drive reservoir with a semi-permeable barrier. Besides, analytical equations were also presented to calculate critical parameters, such as production rate,pressure and potential difference. The effects of barrier, well and reservoir parameters on our model results were further investigated.The results show that the larger the barrier size is or the higher the barrier location is, the higher the critical production rate and potential difference of a horizontal well are. When the barrier permeability equals the formation permeability or the barrier width equals zero, the critical production rates converge to the values same to that of the case with no barrier. When the barrier permeability equals zero, the problem is regarded as a case of impermeable barrier. This model can be applied to predicting horizontal wells' critical production parameters in reservoirs with semi-permeable barriers.展开更多
Directing at the non-linear dynamic characteristics of water inrush from coal seam floor and by the analysis of the shortages of current forecast methods for water inrush from coal seam floor, a new forecast method wa...Directing at the non-linear dynamic characteristics of water inrush from coal seam floor and by the analysis of the shortages of current forecast methods for water inrush from coal seam floor, a new forecast method was raised based on wavelet neural network （WNN） that was a model combining wavelet function with artificial neural network. Firstly basic principle of WNN was described, then a forecast model for water inrush from coal seam floor based on WNN was established and analyzed, finally an example of forecasting the quantity of water inrush from coal floor was illustrated to verify the feasibility and superiority of this method. Conclusions show that the forecast result based on WNN is more precise and that using WNN model to forecast the quantity of water inrush from coal seam floor is feasible and practical.展开更多
基金Projects 40372123, 40772192 supported by the National Natural Science Foundation of ChinaNCET-04-0486 by the Program for New Century Excellent Talents in University of China2007CB209400 by the National Basic Research Program of China
文摘With an increase of mining the upper limits under unconsolidated aquifers, dewatering of the bottom aquifer of the Quaternary system has become a major method to avoid water and sand inrushes.In the 8th District of the Taiping Coal Mine in south-western Shandong province, the bottom aquifer of the Quaternary system is moderate to excellent in water-yielding capacity.The base rock above the coal seam is very thin in the concealed coal field of the Carboniferous and Permian systems.Therefore, a comprehensive dewatering plan from both the ground surface and the panel was proposed to lower the groundwater level in order to ensure mining safety.According to the hydrogeologic conditions of the 8th District, we established a numerical model so that we could simulate the groundwater flow in the dewatering process.We obtained the simulation parameters from previous data using backward modeling, such as the average coefficient of permeability of 12 m/d and the elastic storage coefficient of 0.002.From the same model, we predicted the movement of groundwater and water level variables and obtained the visible effect of the dewatering project.Despite the overburden failure during mining, no water and/or sand inrush occurred because the groundwater level in the bottom aquifer was lowered to a safe water level.
基金Supported by the National Natural Science Foundation of China(No.40676011)the Key Technology Research and Development Program of China(No.2006BAB18B02)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20100132110016)
文摘As a unique low-temperature water mass in Antarctic coastal region, the Ice Shelf Water (ISW) is an important component for the formation of the Antarctic Bottom Water (AABW). In this paper, we present a criterion for ISW identification based on freezing point at the sea surface, and we study spatial distribution of ISW in front of the Amery Ice Shelf (AIS) and its flow path in Prydz Bay by analyzing hydrographic data from Australian cruises in 2001 and 2002, as well as Chinese cruises in 2003, 2005, 2006, and 2008, all being made in the austral summer. The relatively cold and fresh ISW occurred as several discrete water blocks with cold cores in front of the AIS, within the depth range of 100?600 m, under the seasonal thermocline. ISW had obvious temporal and spatial variations and the spatial distribution pattern changed greatly after 2005. Most of ISW was concentrated west of 73°E during 2001 to 2003 and 2006, but it was widespread to east in 2005 and 2008. In all observation years, a small amount of cold ISW always occurs at the west end of the AIS front section, where the coldest ISW in the whole section also occurred in 2001, 2003 and 2006. Considering general cyclonic circulation pattern under the AIS, the ISW flowing out from west end of the AIS front might have experienced the longest cooling period under ice shelf, so it would have the lowest temperature. Analysis of data from meridian sections in Prydz Bay in 2003 implied that ISW in the west could spread north to the continental break along the east flank of the Fram Bank near 70.5°E, mix with the upwelling Circumpolar Deep Water and possibly contribute to the formation of AABW.
基金the National Natural Science Foundation of China (No. 51304209)the Basic Research Program of Jiangsu Province (Natural Science Foundation) (No. BK20130179)
文摘Serious shaft lining failures often occur when shaft linings are constructed by passing them through the deep topsoil of Quaternary strata. This approach also leads to the formation of an aquifer at the bottom.Based on the theory of the additional stress which is the main reason for these failures, this study focuses on the treatment effect of underground continuous impervious curtain(UCIC) in terms of different factors, namely, the location, shape, range, and width, by using numerical simulation. Results show that the UCIC can reduce the stress concentration in the shaft lining formed in the bottom aquifer. The UCIC can also reinforce the shaft lining at different angles and can be applied in actual situations. The strength factors of the inner surface of the shaft lining increase after the UCIC are used. The material strength and width of the UCIC show an obvious effect on the stability of the shaft lining. Results proved that the UCIC could effectively strengthen the stability of the shaft lining when it was built in the aquifer or built in the aquifer and above and below the layer.
基金supported by the National Basic Research Program ofChina(No.2010CB202210)the National Natural Science Foundation of China(No.50874103)+1 种基金the Natural Science Foundation of Jiangsu Province(No.KB2008135)as well as by the Qinglan Project of Jiangsu Province
文摘The failure depth of the coal seam floor is one important consideration that must be kept in mind when mining is carried out above a confined aquifer.Determining the floor failure depth is the essential precondition for predicting the water-resisting ability of the floor.We have used a high-precision microseismic monitoring technique to overcome the limited amount of data available from field measurements. The failure depth of a coal seam floor,especially an inclined coal seam floor,may be more accurately estimated by monitoring the continuous,dynamic failure of the floor.The monitoring results indicate the failure depth of the coal seam floor near the workface conveyance roadway（the lower crossheading） is deeper and that the failure range is wider here compared to the coal seam floor near the return airway（the upper crossheading）.The results of micro-seismic monitoring show that the dangerous area for water-inrush from the coal seam floor may be identified.This provides an important field measurement that helps ensure safe and highly efficient mining of the inclined coal seam above the confined aquifer at the Taoyuan Coal Mine.
基金supported by the National Basic Research Program of China (No. 2007CB209400)the National Natural Science Foundation of China (Nos. 50634050,50834004,50874103 and 50904065) the Young Scientists Fund of the School Science Foundation of CUMT (No. 2008A046)
文摘With the increase in mining depth many mining areas in China have entered a period necessitating mining above aquifers. Production safety in coal mines in northern China is under serious threat from Ordovician karst water on coal seam floors, in order to analyze the destruction of water-resisting strata in floors of coal seams being mined and to achieve safe mining above deep aquifers, we established a numerical model of water-resisting strata, considering the structural characteristics and mechanical properties of a floor layered with hard and soft rock. We simulated the distribution characteristics of deformation, failure and seepage using the analytical module of fluid-structure interaction of FLAt：. We also obtained the corresponding stress distribution, deformation and flow vectors. Our results indi- cate that： （1） the advance of the working face causes water-resisting strata in goaf floors to form a deep double-clamped beam, subject to homogeneous loading at the bottom; （2） the two sides of the rock beam are subject 1~0 shear failure; （3） both sides of the rock seam at the bottom of the water-resisting strata are subject to tension and the greater the working face advance, the more serious the failure; C4） the original balance of the stress and seepage fields are broken and redistributed due to mining activities, especially the interaction of the abutment pressure in both sides of the goal; the lateral pressure on the goal floor and the water pressure on the floor of the aquifer promote floor heave and shear failure on both sides of the floor, forming a water-inrush passage. Our study results can provide references for the mechanism of water-inrush on mine floors.
基金Project(51404201)supported by the National Natural Science Foundation of ChinaProject(2011ZX05024-003)supported by the National Science and Technology Major Project of China+1 种基金Project(14ZB0045)supported by the Scientific Project of Sichuan Provincial Education Department,ChinaProject(2015JY0076)supported by Basic Application Research of Science and Technology Department of Sichuan Province,China
文摘It is well-known that barriers have a significant impact on the production performance of horizontal wells developed in a bottom water drive reservoir. In most cases, reservoir barriers are semi-permeable. Based on previous research on impermeable reservoir barrier, a mathematical flow model was derived for a horizontal well of a bottom water drive reservoir with a semi-permeable barrier. Besides, analytical equations were also presented to calculate critical parameters, such as production rate,pressure and potential difference. The effects of barrier, well and reservoir parameters on our model results were further investigated.The results show that the larger the barrier size is or the higher the barrier location is, the higher the critical production rate and potential difference of a horizontal well are. When the barrier permeability equals the formation permeability or the barrier width equals zero, the critical production rates converge to the values same to that of the case with no barrier. When the barrier permeability equals zero, the problem is regarded as a case of impermeable barrier. This model can be applied to predicting horizontal wells' critical production parameters in reservoirs with semi-permeable barriers.
文摘Directing at the non-linear dynamic characteristics of water inrush from coal seam floor and by the analysis of the shortages of current forecast methods for water inrush from coal seam floor, a new forecast method was raised based on wavelet neural network （WNN） that was a model combining wavelet function with artificial neural network. Firstly basic principle of WNN was described, then a forecast model for water inrush from coal seam floor based on WNN was established and analyzed, finally an example of forecasting the quantity of water inrush from coal floor was illustrated to verify the feasibility and superiority of this method. Conclusions show that the forecast result based on WNN is more precise and that using WNN model to forecast the quantity of water inrush from coal seam floor is feasible and practical.
