Nowadays, the researches of using Differential Interferometric Synthetic Aperture Radar (D-InSAR) tech- nique to monitor the land subsidence are mainly on how to qualitatively analyze the subsidence areas and values, ...Nowadays, the researches of using Differential Interferometric Synthetic Aperture Radar (D-InSAR) tech- nique to monitor the land subsidence are mainly on how to qualitatively analyze the subsidence areas and values, but the analysis of subsidence process and mechanism are insufficient. In order to resolve these problems, 6 scenes of ERS1/2 images captured during 1995 and 2000 in a certain place of Jiangsu province were selected to obtain the subsidence and velocities in three time segments by ''two-pass'' D- InSAR method. Then the relationships among distributions of pumping wells, exploitation quantity of groundwater, and confined water levels were studied and the subsidence mechanism was systematically analyzed. The results show that using D-InSAR technique to monitor the deformation of large area can obtain high accuracies, the disadvantages of classical observation methods can be remedied and there is a linear relationship among the velocities of land subsidence, the water level and the exploitation quantity.展开更多
A technique for modelling of three-dimensional(3D)quasi-statically propagating cracks in elastic bodies by the displacement discontinuity method(DDM)was described.When the crack is closed,the Mohr-coulomb rule on the ...A technique for modelling of three-dimensional(3D)quasi-statically propagating cracks in elastic bodies by the displacement discontinuity method(DDM)was described.When the crack is closed,the Mohr-coulomb rule on the two contacted surfaces of the crack must be satisfied.A simple iterative method was adopted in order to consider three different states of cracks.Under the assumption that the advance of the point on the crack front would occur only in the normal plane which is through this edge point,the maximum energy release rate criterion is modified to be used as the criterion for the crack growth.With discretization,the process of crack propagation can be seen as the advance of the vertices of the crack front.The program MCP3D was developed based on these theories to simulate the 3D quasi-static crack propagation.A numerical example of a penny-shaped crack subject to tension and compression in an infinite elastic media was analyzed with MCP3D,and the results in comparison with others' show that the present method for 3D crack propagation is effective.展开更多
There is a potential to certain extend for groundwater development in the piedmont plain in south edge of Tarim Basin. If the surface water use keeps the scale as present, the maximum safe yield of groundwater is abou...There is a potential to certain extend for groundwater development in the piedmont plain in south edge of Tarim Basin. If the surface water use keeps the scale as present, the maximum safe yield of groundwater is about 2.05 × 109m3/a that is 55.8% of the recharge. Thus the evapotranspiration discharge will reduce 60.4%, while spring water reducing 35.6%. If the surface water use rate is up to 80% and coefficient of canal water use increase to 0.55 in the future, the maximum safe yield of groundwater will reduce to 1.85 × 109m3/a with the recharge reducing to 3.1 × 109m3. However, the sustainable groundwater development is depended on the protection of the quality aspect linked with the quantity aspect. In particular, protection of the glaoier and water conservation forestry in the Kunlun Mountains and coordinating development of surface water and groundwater should be taken seriously. Besides, the legislation, administrative management and the technology construction, and ability construction are also critical important and necessary.展开更多
In order to study the effect of Iongwall mining on surface stream water, monitoring stations of water flow rate was established. A lot of water flowing data were collected before, during and after Iongwall mining. Bas...In order to study the effect of Iongwall mining on surface stream water, monitoring stations of water flow rate was established. A lot of water flowing data were collected before, during and after Iongwall mining. Based on monitoring data, the effects of Iongwall mining on surface stream water were analyzed. The results demonstrate that Iongwall mining has effects on the surface stream water; and the stream water would be lost and decrease due to Iongwall mining but never go into underground through fractured zone. Also, the mechanism of water loss due to Iongwall mining was presented. The stream water can go into the surface cracks in the intersection of stream and surface cracks, longwall mining subsidence can change the surface stream slope and the downstream water flowing status. The results also show the effects of Iongwall mining on stream water are temporary and about one or two years later, surface stream water can be recovered.展开更多
To make a better understanding of the mechanical characteristics of the surrounding rocks in the tailentry and headentry with different coal seam thickness at fully mechanized top-coal caving face (FMTC face), the s...To make a better understanding of the mechanical characteristics of the surrounding rocks in the tailentry and headentry with different coal seam thickness at fully mechanized top-coal caving face (FMTC face), the stress transition and displacement around the periphery of the gateways with different coal thicknesses were investigated in details by means of in situ measurement and 3-D numerical simulation. The research shows that the stresses decrease in the two spallings of the headentry and floor at goal with the increase in mining thickness. The roof pressure in the gates does not change obviously with the coal thickness, but the thicker the coal seam is, the farther the maximum stress will apply to the coal rib at the working face. The vertical stress is higher than the horizontal stress at two spallings of the gate, while its horizontal stress is higher than the vertical stress at the roof. The relative displacement between the roof and floor and the two spallings in the gateways increases gradually with the increase in coal seam thickness in a definite range in front of the face. Near the mining face, the stress decreases in the surrounding rock of the gates, while the deformation appears the most intensive. It is proposed that the support concept to the tailentry and headentry should be changed from loading control to deformation control.展开更多
This article presents the results of dividing the hydrogeological structure zones in aquifer of Cai Phan Rang river basin, Ninh Thuan province, Viet Nam, and the relationship between parameters of hydrogeological stru...This article presents the results of dividing the hydrogeological structure zones in aquifer of Cai Phan Rang river basin, Ninh Thuan province, Viet Nam, and the relationship between parameters of hydrogeological structure zones with water storage capacity of hydrogeological structure. Research results divided hydrogeological structure of Cai Phan Rang River Basin into four zones, including three zones with depression bedrock and one zone with slope bedrock, and the results assessed: (1) specific discharge of exploitation well is proportional to zone area of hydrogeological structure; (2) specific discharge of exploitation well is inversely proportional to slope of bedrock surface, slope of water level in zone and area of drainage surface of hydrogeological structure zone; (3) water level fluctuation in zone is proportional to slope of bedrock surface, slope of water level in zone and inversely proportional to distribution area of zone; (4) total mineralization of water is proportional to bedrock surface slope and water level slope in zone, and inversely proportional to drainage surface area of zone and volume of structural depression. Research results are practical significance in solutions proposal to increase exploitation capacity for various water use purposes.展开更多
The site drilling packer permeability test and TEM to the 2100 workface in Gucheng coalmine determined the two-zone height under sublevel strip mining.The conclusion considers that the lying strata deterioration law o...The site drilling packer permeability test and TEM to the 2100 workface in Gucheng coalmine determined the two-zone height under sublevel strip mining.The conclusion considers that the lying strata deterioration law of the strip mining is similar to that of the sublevel mining.Thus, against that the actually measured data lacked, it is feasible to refer to the reservation of the waterproof coal pillar in the neighbor coalmine under sublevel situation.However, it is necessary to further launch the research on lying strata deterioration law under sublevel striping mining for the purpose of providing the right foundation for the layout of the workface not mined so far and the reservation of the waterproof coal pillar in the mining area.展开更多
The Aral Sea was one of the largest lakes in the world before it started to shrink in the 1960s due to water withdrawal for agricultural irrigation. Precipitation decreased from 9.4 kmin 1960 to 3.2 km3 in 2009, and a...The Aral Sea was one of the largest lakes in the world before it started to shrink in the 1960s due to water withdrawal for agricultural irrigation. Precipitation decreased from 9.4 kmin 1960 to 3.2 km3 in 2009, and annual river inflow into the Aral Sea decreased from 31.5 km3 in 1998 to 5.2 km3 in 2009. Comparison on the hydrological data of the Aral Sea between 1960 and 2009 showed the evaporation, water surface area, and water volume decreased by 90%, 80%, and 88%, respectively. This study employs the observed values of water volume, precipitation, runoff, evaporation, and salinity to estimate water volume and salinity from 1960 to 2009, and the efficiency coefficients for predicted water volume and salinity are o.975 and 0.974, respectively. Regression equations calculated from the observed data are used to predict precipitation, runoff, evaporation, and salinity from 20lO to 2021, and the results are then applied in the estimation of water volume and salinity Our estimates suggest that salinity will increase to around 200 g/L and water volume will decrease to around 83 km3 in 2021.展开更多
The nonlinear Hoek-Brown failure criterion was introduced to limit analysis by applying the tangent method. Based on the failure mechanism of double-logarithmic spiral curves on the face of deep rock tunnels, the anal...The nonlinear Hoek-Brown failure criterion was introduced to limit analysis by applying the tangent method. Based on the failure mechanism of double-logarithmic spiral curves on the face of deep rock tunnels, the analytical solutions of collapse pressure were derived through utilizing the virtual power principle in the case of pore water, and the optimal solutions of collapse pressure were obtained by using the optimization programs of mathematical model with regard of a maximum problem. In comparison with existing research with the same parameters, the consistency of change rule shows the validity of the proposed method. Moreover, parametric study indicates that nonlinear Hoek-Brown failure criterion and pore water pressure have great influence on collapse pressure and failure shape of tunnel faces in deep rock masses, particularly when the surrounding rock is too weak or under the condition of great disturbance and abundant ground water, and in this case, supporting measures should be intensified so as to prevent the occurrence of collapse.展开更多
The effects of surface cracks caused by underground coal mining on microhabitat in the rhizosphere of Artem&ia ordosias were studied based on field investigation and sample analysis. The results show that the amounts...The effects of surface cracks caused by underground coal mining on microhabitat in the rhizosphere of Artem&ia ordosias were studied based on field investigation and sample analysis. The results show that the amounts of microorganisms, enzyme activity and water content in soil vary with the biomass ofA. ordosias, and that the account exhibits in an order of large A. ordosias〉medium A. ordosias〉small A. ordosias. Surface cracks apparently decrease microbial quantities and enzymatic ac- tivities, and change the composition and structure of microbial community in the rhizosphere of A. ordosias. Surface cracks reduce water content and electrical conductivity, enhance the R/S (ratio of root and soil) of water content, electrical conductivity and pH value, and raise the content of Na and Pb in rhizosphere soil ofA. ordosicas, It can be concluded that the disturbance of underground coal mining on the microhabitat in the rhizosphere ofA. ordosica is obvious in the early days.展开更多
Traditional smoking of fish in Nigeria is often carried out in open and unsanitary environment. In addition, the current process does not result in uniformly smoked fish and uses wood (an increasingly scarce material...Traditional smoking of fish in Nigeria is often carried out in open and unsanitary environment. In addition, the current process does not result in uniformly smoked fish and uses wood (an increasingly scarce material) as heat source. The fish smoking kiln designed and fabricated in this study addresses these problems. The kiln (700 × 800 × 1,500 mm) is made of stainless steel on the inside and mild steel on the outside with glass fiber insulation separating the inside and outside covers. The sample to be smoked is totally enclosed by the kiln with a latchable door provided at one of the sides for placing of samples to be smoked. In addition, the kiln was designed to use waste biomass resource as fuels (sawdust and/or maizecob). Bonga fish (Ethmalosafimbriata) and African catfish (Clarias gariepinus) were used as test samples for the kiln. The temperature of the chamber increased to about 120 ℃ to 160 ℃ when fueled with sawdust and about 150 ℃ to 200 ℃ for maizecob. The total heat transfer resistance through the kiln walls was determined to be 1.0 ℃/W. About 6-8 h was required to smoke-dry 16 kg of fish samples from initial moisture content of 75% to about 25% or 20% moisture level.展开更多
Retaining gob-side entryways and the stability of gas drainage boreholes are two essential techniques in the co-extraction of coal and gas without entry pillars (CECGWEP). However, retained entryways located in deep...Retaining gob-side entryways and the stability of gas drainage boreholes are two essential techniques in the co-extraction of coal and gas without entry pillars (CECGWEP). However, retained entryways located in deep coal mines are hard to maintain, especially for constructing boreholes in confined spaces, owing to major deformations. Consequently, it is difficult to drill boreholes and maintain their stability, which therefore cannot guarantee the effectiveness of gas drainage. This paper presents three measures for conducting CECGWEP in deep mines on the basis of effective space in retained entryways for gas drainage, They are combinations of retaining roadways and face-lagging inclined boreholes, retaining roadways and face-advancing inclined boreholes, and retaining roadways and high return airway inclined boreholes. Several essential techniques are suggested to improve the maintenance of retained entryways and the stabilization of boreholes. For the particular cases considered in this study, two field trials have verified the latter two measures from the results obtained from the faces 1111(1) and 11112(1) in the Zhuji Mine. The results indicate that these models can effectively solve the problems in deep mines. The maximum gas drainage flow for a single hole can reach 8.1 m^3/min and the effective drainage distance can be extended up to 150 m or more.展开更多
The access to safe drinking-water is a global priority for sustainable development, as it has been recognized within the MDGs (Millennium Development Goals). Although the MDG’s target of halving the proportion of p...The access to safe drinking-water is a global priority for sustainable development, as it has been recognized within the MDGs (Millennium Development Goals). Although the MDG’s target of halving the proportion of people without sustainable access to safe drinking-water was met in 2010, the measurement method of the monitoring and evaluation indicator used ignored certain elements including the quality of water that should be underlined. Starting with a review of drinking-water and improved water source concepts, this study examines the limitations of measuring access to safe drinking-water in the context of the MDGs, and learns from the lessons to ensure a better performance in achieving the SDGs (Sustainable Development Goals).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
For the question of applying high-pressure water injection to increase gas extraction efficiency by increasing the permeability of water to drive gas action, an independently designed gas desorption experimental measu...For the question of applying high-pressure water injection to increase gas extraction efficiency by increasing the permeability of water to drive gas action, an independently designed gas desorption experimental measuring device was used under the condition of external solution invasion. The law of water effect on gas desorption was obtained after water invasion through experiment for the first time. The results show that water's later invasion not only can make the quantity of gas dcsorp- tion greatly reduced, but also can make gas desorption end early. Therefore, when evaluating the applications of high-pressure water injection to increase gas extraction efficiency, we should take water damaging effects on gas desorption into account.展开更多
Crop coefficients (Kc) of sugar beet were determined for accurate calculation of water requirements (CWR) and better irrigation water management. Three irrigation treatments were used during two seasons to measure...Crop coefficients (Kc) of sugar beet were determined for accurate calculation of water requirements (CWR) and better irrigation water management. Three irrigation treatments were used during two seasons to measure actual crop water use (ETc) under no soil stress treatment using gravimetric sampling. In the second season (SS), the method was modified to target 8 temporal points during crop growth for smooth calculation of ETc under sufficient moisture supply to avoid the distortion that was created by the continuous gravimetric sampling after, before and during each irrigation cycle on the experimental plots. Water was stopped when each targeted sampling point was reached using large plots where intensive sampling continues until the crop reaches severe water stress or permanent wilting point (PWP). The actual crop water use was extracted from the soil moisture depletion curve which allowed the identification of two clear segments. The first segment indicated crop water use during no water stress while the change of the slope indicated the beginning of the water stress. The reference crop evapotranspiration (ET0) was determined on daily basis using appropriate weather data that coincides with the ETc measurement and consequently the crop Kc were calculated. The results showed that the method used during the SS is easy and provides a better understanding of actual crop water use and better estimation of crop Kc. The calculated 10-day Kc values for sugar beet under heavy cracking clay soil conditions were: 0.46, 0.49, 0.53 and 0.60; for the initial stage: 0.69, 0.78, 0.88 and 0.97; for the development stage: 1.05, 1.11, 1.13, 1.11 and 1.04; for mid-season stage and for late season stage: 0.92, 0.74 and 0.60. Yield and other sugar related parameters were also presented for the two seasons.展开更多
基金provided by the National Natural Science Foundation of China (No.41071273)the Fundamental Research Funds for the Central Universities (No. 2010QNA21)the Project Sponsored by the Scientific Research Foundation of Key Laboratory for Land Environmentand Disaster Monitoring of SBSM (No. LEDM2011B07)
文摘Nowadays, the researches of using Differential Interferometric Synthetic Aperture Radar (D-InSAR) tech- nique to monitor the land subsidence are mainly on how to qualitatively analyze the subsidence areas and values, but the analysis of subsidence process and mechanism are insufficient. In order to resolve these problems, 6 scenes of ERS1/2 images captured during 1995 and 2000 in a certain place of Jiangsu province were selected to obtain the subsidence and velocities in three time segments by ''two-pass'' D- InSAR method. Then the relationships among distributions of pumping wells, exploitation quantity of groundwater, and confined water levels were studied and the subsidence mechanism was systematically analyzed. The results show that using D-InSAR technique to monitor the deformation of large area can obtain high accuracies, the disadvantages of classical observation methods can be remedied and there is a linear relationship among the velocities of land subsidence, the water level and the exploitation quantity.
文摘A technique for modelling of three-dimensional(3D)quasi-statically propagating cracks in elastic bodies by the displacement discontinuity method(DDM)was described.When the crack is closed,the Mohr-coulomb rule on the two contacted surfaces of the crack must be satisfied.A simple iterative method was adopted in order to consider three different states of cracks.Under the assumption that the advance of the point on the crack front would occur only in the normal plane which is through this edge point,the maximum energy release rate criterion is modified to be used as the criterion for the crack growth.With discretization,the process of crack propagation can be seen as the advance of the vertices of the crack front.The program MCP3D was developed based on these theories to simulate the 3D quasi-static crack propagation.A numerical example of a penny-shaped crack subject to tension and compression in an infinite elastic media was analyzed with MCP3D,and the results in comparison with others' show that the present method for 3D crack propagation is effective.
基金the auspices of the National Natural Science Foundation of China(No. 49731010).
文摘There is a potential to certain extend for groundwater development in the piedmont plain in south edge of Tarim Basin. If the surface water use keeps the scale as present, the maximum safe yield of groundwater is about 2.05 × 109m3/a that is 55.8% of the recharge. Thus the evapotranspiration discharge will reduce 60.4%, while spring water reducing 35.6%. If the surface water use rate is up to 80% and coefficient of canal water use increase to 0.55 in the future, the maximum safe yield of groundwater will reduce to 1.85 × 109m3/a with the recharge reducing to 3.1 × 109m3. However, the sustainable groundwater development is depended on the protection of the quality aspect linked with the quantity aspect. In particular, protection of the glaoier and water conservation forestry in the Kunlun Mountains and coordinating development of surface water and groundwater should be taken seriously. Besides, the legislation, administrative management and the technology construction, and ability construction are also critical important and necessary.
基金Supported by Pennsylvania Service Corporation at Waynesburg, Pennsylvania, USA the 0utstanding Youth Science Foundation of Henan Province (0612002100), China.
文摘In order to study the effect of Iongwall mining on surface stream water, monitoring stations of water flow rate was established. A lot of water flowing data were collected before, during and after Iongwall mining. Based on monitoring data, the effects of Iongwall mining on surface stream water were analyzed. The results demonstrate that Iongwall mining has effects on the surface stream water; and the stream water would be lost and decrease due to Iongwall mining but never go into underground through fractured zone. Also, the mechanism of water loss due to Iongwall mining was presented. The stream water can go into the surface cracks in the intersection of stream and surface cracks, longwall mining subsidence can change the surface stream slope and the downstream water flowing status. The results also show the effects of Iongwall mining on stream water are temporary and about one or two years later, surface stream water can be recovered.
基金National Natural Science Foundation(50674003)National Science and Technology Supporting Program Key Item(Eleventh Five Year Program)(2006BAK03B06)National Basic Research Program(973 Program)(2005cb221503)
文摘To make a better understanding of the mechanical characteristics of the surrounding rocks in the tailentry and headentry with different coal seam thickness at fully mechanized top-coal caving face (FMTC face), the stress transition and displacement around the periphery of the gateways with different coal thicknesses were investigated in details by means of in situ measurement and 3-D numerical simulation. The research shows that the stresses decrease in the two spallings of the headentry and floor at goal with the increase in mining thickness. The roof pressure in the gates does not change obviously with the coal thickness, but the thicker the coal seam is, the farther the maximum stress will apply to the coal rib at the working face. The vertical stress is higher than the horizontal stress at two spallings of the gate, while its horizontal stress is higher than the vertical stress at the roof. The relative displacement between the roof and floor and the two spallings in the gateways increases gradually with the increase in coal seam thickness in a definite range in front of the face. Near the mining face, the stress decreases in the surrounding rock of the gates, while the deformation appears the most intensive. It is proposed that the support concept to the tailentry and headentry should be changed from loading control to deformation control.
文摘This article presents the results of dividing the hydrogeological structure zones in aquifer of Cai Phan Rang river basin, Ninh Thuan province, Viet Nam, and the relationship between parameters of hydrogeological structure zones with water storage capacity of hydrogeological structure. Research results divided hydrogeological structure of Cai Phan Rang River Basin into four zones, including three zones with depression bedrock and one zone with slope bedrock, and the results assessed: (1) specific discharge of exploitation well is proportional to zone area of hydrogeological structure; (2) specific discharge of exploitation well is inversely proportional to slope of bedrock surface, slope of water level in zone and area of drainage surface of hydrogeological structure zone; (3) water level fluctuation in zone is proportional to slope of bedrock surface, slope of water level in zone and inversely proportional to distribution area of zone; (4) total mineralization of water is proportional to bedrock surface slope and water level slope in zone, and inversely proportional to drainage surface area of zone and volume of structural depression. Research results are practical significance in solutions proposal to increase exploitation capacity for various water use purposes.
基金Supported by Fujian Administration of Education for Science Research (JB08232)the State Key Development Program for Basic Research of China(2006CB202200)
文摘The site drilling packer permeability test and TEM to the 2100 workface in Gucheng coalmine determined the two-zone height under sublevel strip mining.The conclusion considers that the lying strata deterioration law of the strip mining is similar to that of the sublevel mining.Thus, against that the actually measured data lacked, it is feasible to refer to the reservation of the waterproof coal pillar in the neighbor coalmine under sublevel situation.However, it is necessary to further launch the research on lying strata deterioration law under sublevel striping mining for the purpose of providing the right foundation for the layout of the workface not mined so far and the reservation of the waterproof coal pillar in the mining area.
文摘The Aral Sea was one of the largest lakes in the world before it started to shrink in the 1960s due to water withdrawal for agricultural irrigation. Precipitation decreased from 9.4 kmin 1960 to 3.2 km3 in 2009, and annual river inflow into the Aral Sea decreased from 31.5 km3 in 1998 to 5.2 km3 in 2009. Comparison on the hydrological data of the Aral Sea between 1960 and 2009 showed the evaporation, water surface area, and water volume decreased by 90%, 80%, and 88%, respectively. This study employs the observed values of water volume, precipitation, runoff, evaporation, and salinity to estimate water volume and salinity from 1960 to 2009, and the efficiency coefficients for predicted water volume and salinity are o.975 and 0.974, respectively. Regression equations calculated from the observed data are used to predict precipitation, runoff, evaporation, and salinity from 20lO to 2021, and the results are then applied in the estimation of water volume and salinity Our estimates suggest that salinity will increase to around 200 g/L and water volume will decrease to around 83 km3 in 2021.
基金Project(2013CB036004)supported by National Basic Research Program of ChinaProjects(51178468,51378510)supported by National Natural Science Foundation of ChinaProject(CX2013B077)supported by Hunan Provincial Innovation Foundation for Postgraduate,China
文摘The nonlinear Hoek-Brown failure criterion was introduced to limit analysis by applying the tangent method. Based on the failure mechanism of double-logarithmic spiral curves on the face of deep rock tunnels, the analytical solutions of collapse pressure were derived through utilizing the virtual power principle in the case of pore water, and the optimal solutions of collapse pressure were obtained by using the optimization programs of mathematical model with regard of a maximum problem. In comparison with existing research with the same parameters, the consistency of change rule shows the validity of the proposed method. Moreover, parametric study indicates that nonlinear Hoek-Brown failure criterion and pore water pressure have great influence on collapse pressure and failure shape of tunnel faces in deep rock masses, particularly when the surrounding rock is too weak or under the condition of great disturbance and abundant ground water, and in this case, supporting measures should be intensified so as to prevent the occurrence of collapse.
文摘The effects of surface cracks caused by underground coal mining on microhabitat in the rhizosphere of Artem&ia ordosias were studied based on field investigation and sample analysis. The results show that the amounts of microorganisms, enzyme activity and water content in soil vary with the biomass ofA. ordosias, and that the account exhibits in an order of large A. ordosias〉medium A. ordosias〉small A. ordosias. Surface cracks apparently decrease microbial quantities and enzymatic ac- tivities, and change the composition and structure of microbial community in the rhizosphere of A. ordosias. Surface cracks reduce water content and electrical conductivity, enhance the R/S (ratio of root and soil) of water content, electrical conductivity and pH value, and raise the content of Na and Pb in rhizosphere soil ofA. ordosicas, It can be concluded that the disturbance of underground coal mining on the microhabitat in the rhizosphere ofA. ordosica is obvious in the early days.
文摘Traditional smoking of fish in Nigeria is often carried out in open and unsanitary environment. In addition, the current process does not result in uniformly smoked fish and uses wood (an increasingly scarce material) as heat source. The fish smoking kiln designed and fabricated in this study addresses these problems. The kiln (700 × 800 × 1,500 mm) is made of stainless steel on the inside and mild steel on the outside with glass fiber insulation separating the inside and outside covers. The sample to be smoked is totally enclosed by the kiln with a latchable door provided at one of the sides for placing of samples to be smoked. In addition, the kiln was designed to use waste biomass resource as fuels (sawdust and/or maizecob). Bonga fish (Ethmalosafimbriata) and African catfish (Clarias gariepinus) were used as test samples for the kiln. The temperature of the chamber increased to about 120 ℃ to 160 ℃ when fueled with sawdust and about 150 ℃ to 200 ℃ for maizecob. The total heat transfer resistance through the kiln walls was determined to be 1.0 ℃/W. About 6-8 h was required to smoke-dry 16 kg of fish samples from initial moisture content of 75% to about 25% or 20% moisture level.
基金Acknowledgments The research was supported by Program for Changjiang Scholars and Innovative Research Team in University (IRT_I4R55), and the National Natural Science Foundation of China under Grant No. NSFC-51274193.
文摘Retaining gob-side entryways and the stability of gas drainage boreholes are two essential techniques in the co-extraction of coal and gas without entry pillars (CECGWEP). However, retained entryways located in deep coal mines are hard to maintain, especially for constructing boreholes in confined spaces, owing to major deformations. Consequently, it is difficult to drill boreholes and maintain their stability, which therefore cannot guarantee the effectiveness of gas drainage. This paper presents three measures for conducting CECGWEP in deep mines on the basis of effective space in retained entryways for gas drainage, They are combinations of retaining roadways and face-lagging inclined boreholes, retaining roadways and face-advancing inclined boreholes, and retaining roadways and high return airway inclined boreholes. Several essential techniques are suggested to improve the maintenance of retained entryways and the stabilization of boreholes. For the particular cases considered in this study, two field trials have verified the latter two measures from the results obtained from the faces 1111(1) and 11112(1) in the Zhuji Mine. The results indicate that these models can effectively solve the problems in deep mines. The maximum gas drainage flow for a single hole can reach 8.1 m^3/min and the effective drainage distance can be extended up to 150 m or more.
文摘The access to safe drinking-water is a global priority for sustainable development, as it has been recognized within the MDGs (Millennium Development Goals). Although the MDG’s target of halving the proportion of people without sustainable access to safe drinking-water was met in 2010, the measurement method of the monitoring and evaluation indicator used ignored certain elements including the quality of water that should be underlined. Starting with a review of drinking-water and improved water source concepts, this study examines the limitations of measuring access to safe drinking-water in the context of the MDGs, and learns from the lessons to ensure a better performance in achieving the SDGs (Sustainable Development Goals).
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.
文摘For the question of applying high-pressure water injection to increase gas extraction efficiency by increasing the permeability of water to drive gas action, an independently designed gas desorption experimental measuring device was used under the condition of external solution invasion. The law of water effect on gas desorption was obtained after water invasion through experiment for the first time. The results show that water's later invasion not only can make the quantity of gas dcsorp- tion greatly reduced, but also can make gas desorption end early. Therefore, when evaluating the applications of high-pressure water injection to increase gas extraction efficiency, we should take water damaging effects on gas desorption into account.
文摘Crop coefficients (Kc) of sugar beet were determined for accurate calculation of water requirements (CWR) and better irrigation water management. Three irrigation treatments were used during two seasons to measure actual crop water use (ETc) under no soil stress treatment using gravimetric sampling. In the second season (SS), the method was modified to target 8 temporal points during crop growth for smooth calculation of ETc under sufficient moisture supply to avoid the distortion that was created by the continuous gravimetric sampling after, before and during each irrigation cycle on the experimental plots. Water was stopped when each targeted sampling point was reached using large plots where intensive sampling continues until the crop reaches severe water stress or permanent wilting point (PWP). The actual crop water use was extracted from the soil moisture depletion curve which allowed the identification of two clear segments. The first segment indicated crop water use during no water stress while the change of the slope indicated the beginning of the water stress. The reference crop evapotranspiration (ET0) was determined on daily basis using appropriate weather data that coincides with the ETc measurement and consequently the crop Kc were calculated. The results showed that the method used during the SS is easy and provides a better understanding of actual crop water use and better estimation of crop Kc. The calculated 10-day Kc values for sugar beet under heavy cracking clay soil conditions were: 0.46, 0.49, 0.53 and 0.60; for the initial stage: 0.69, 0.78, 0.88 and 0.97; for the development stage: 1.05, 1.11, 1.13, 1.11 and 1.04; for mid-season stage and for late season stage: 0.92, 0.74 and 0.60. Yield and other sugar related parameters were also presented for the two seasons.