Pb2+ and Cd2+ in leachate were adsorbed on clay-solidified grouting curtain for waste landfills with equilibrium experiment. The cation exchange capacity was determined with ammonium acetate. And the concentration of ...Pb2+ and Cd2+ in leachate were adsorbed on clay-solidified grouting curtain for waste landfills with equilibrium experiment. The cation exchange capacity was determined with ammonium acetate. And the concentration of heavy metal cations in leachate was determined with atomic absorption spectrophotometer. Their equilibrium isotherms were measured, and the experimental isotherm data were analyzed by using Freundlich and Langmuir models. The results show that the adsorption capacities of the heavy metal cations are closely related to the compositions of clay-solidified grouting curtain, and the maximum adsorption appears at the ratio of cement to clay of 2∶4 in the experimental conditions. At their maximum adsorption and pH 5.0, the adsorption capacities of Pb 2+ and Cd 2+ are 16.19mg/g and 1.21mg/g. The competitive adsorption coefficients indicate that the adsorption of clay-solidified grouting curtain for Pb2+ is stronger than that for Cd 2+ . The adsorption process conforms to Freundlich’s model with related coefficient higher than 0.996.展开更多
A new air distribution pattern,air curtain jet ventilation was presented.The ventilation or airflow patterns and the air velocity produced by air curtain jet were investigated in detail.To identify the airflow charact...A new air distribution pattern,air curtain jet ventilation was presented.The ventilation or airflow patterns and the air velocity produced by air curtain jet were investigated in detail.To identify the airflow characteristics of this novel air curtain jet ventilation system,a full-scale room was used to measure the jet velocity with a slot-ventilated supply device,with regards to the airflow fields along the vertical wall as well as on the horizontal floor zones.The airflow fields under three supply air velocities,1.0,1.5 and 2.0 m/s,were carried out in the full-scale room.The experimental results show the velocity profiles of air distribution,the airflow fields along the attached vertical wall and the air lake zones on the floor,respectively.The current experimental research is helpful for heating,ventilation and air conditioning(HVAC) engineers to design better air distribution in rooms.展开更多
The effects of components and their ratio of grouts on anti-seepage capability of clay-solidified grouting curtain and its permeability of heavy metal cations were investigated by permeating experiments, using reactiv...The effects of components and their ratio of grouts on anti-seepage capability of clay-solidified grouting curtain and its permeability of heavy metal cations were investigated by permeating experiments, using reactive solute transport model to study the permeation of heavy metals (Cd2+, Pb2+ and Hg2+). The study of permeating for different mixture ratios of cement and clay indicates that hydraulic conductivity of clay-solidified grouting curtain with different ratios of solid to liquid or with the same ratio of solid to liquid but with different ratios of cement to clay is changed. The laboratory simulation test results also show that precipitates produced in heavy metal cation migration process in curtain block up water flowing passage which makes the hydraulic conductivity of the solution-permeated curtain decrease with the leakage time. The permeation velocities for different heavy metal cations vary with ionic concentration, exchange capacity and ion radius etc. The test results indicate that the permeation rapidity order of heavy metals cations in clay-solidified grouting curtain is Hg2+>Pb2+ in the same experimental circumstance. In addition, permeability for different mixture ratios and antisepsis capabilities of clay-solidified grouting curtain were studied in tests.展开更多
Batch experiments were conducted to study the adsorption of phenol on clay-solidified grouting curtain (CSGC) and the effects of contact time,pH and adsorbent concentration on the adsorption were investigated.Under th...Batch experiments were conducted to study the adsorption of phenol on clay-solidified grouting curtain (CSGC) and the effects of contact time,pH and adsorbent concentration on the adsorption were investigated.Under the experimental conditions used,2 d was adequate to determine the equilibrium of phenol adsorption onto CSGC.The amount of phenol adsorbed by CSGC from an initial concentration of 100mg/L was found to be 8.4mg/g.The adsorption process includes particle diffusion and liquid film diffusion,and the latter is the predominating step of the adsorption process.The adsorption ability of CSGC decreased with pH but it increased non-linearly with the CSGC concentration.The optimized concentration for CSGC was found to be 20g/L for the adsorption of 100mg/L phenol.展开更多
The seepage under a dam foundation is mainly controlled by the performance of the curtain.Its anti-seepage behavior may be weakened by the long term physic-chemical actions from groundwater.According to seepage hydrau...The seepage under a dam foundation is mainly controlled by the performance of the curtain.Its anti-seepage behavior may be weakened by the long term physic-chemical actions from groundwater.According to seepage hydraulics and geochemistry theory,a coupling model for assessing the behavior of the curtain under a dam foundation is set up,which consists of seepage module,solute transport module,geochemistry module and curtain erosion module,solved by FEM.A case study was carried out.The result shows that the curtain efficiency is weakened all the time.Aqueous calcium from the curtain is always in dissolution during the stress period for simulation,which leads to the increasing amount in groundwater reaching 846.35-865.312 g/m3.Within the domain,reaction extent differs in different parts of the curtain.The dissolution of Ca(OH)2 accounts to 877.884 g/m3 near the bottom and is much higher than that of the other parts.The erosion is much more serious near the bottom of the curtain than the other parts,which is the same to the upstream and downstream.Calcium dissolution is mainly controlled by hydraulic condition and dispersion,and it varies in a non-linear way within the domain.展开更多
Clay-solidified grouting curtains are commonly used for remediation by containment or pollution prevention, in addition to their use as a barrier to water flow in municipal solid waste(MSW) landfills. A hydrological m...Clay-solidified grouting curtains are commonly used for remediation by containment or pollution prevention, in addition to their use as a barrier to water flow in municipal solid waste(MSW) landfills. A hydrological model.of water flow and a hydrodynamic model of contaminant are presented to simulate the migration of leachate through clay-solidified grouting curtain in MSW landfills, with particular attention paid to the role of diffusive and adsorptive fluxes in contaminant transport. The models were applied to simulate the sensitivity of the curtain's behavior to changes in parameters, such as thickness, depth, permeability coefficient, diffusion coefficient,resistance coefficient and concentration, and also to demonstrate the contaminant distribution on the evolution of travel time and offset distance of clay-solidified grouting curtain in landfills. It is found that a part of leachate components stays or is retarded in clay-solidified grouting curtain by precipitate or exchange, the retention rate is closely related to composition of clay-solidified grouting curtain, more than 800%, and the maximum occurs at the cementclay ratio of 2: 4 under experimental conditions. Contamination distribution is variable on travel time and offset distance, the highest concentration takes place where the contamination intensity is nearest to the pollution resource or takes place at early middle period of transport, and the pollutant attenuates gradually. The results indicate that claysolidified grouting curtain with a proper thickness, a low permeability coefficient and a high resistance coefficient might serve as a sufficiently effective vertical barrier against leachate seepage and contamination migration in MSWlandfills.展开更多
The present problem of mining of narrow and gentle dip vein was analyzed. A new technique of rapidly following curtain filling was put forward. The results show that the new technique is feasible, has the characterist...The present problem of mining of narrow and gentle dip vein was analyzed. A new technique of rapidly following curtain filling was put forward. The results show that the new technique is feasible, has the characteristic to make the whole curtain wall filter, makes relative density of the filling tailings slurry reach saturation of 78.0% 80.0% in 25 min, and keeps the roof of mined out space stable in 60 min. The new technique of the rapidly following curtain filling has solved the difficult problem of the filling body filtering slowly and promptly controlling underground pressure, which cannot be solved in traditional ways.展开更多
A partition solution implemented by a cold air curtain for two asymmetric discrete heat sources in a twodimensional rectangular enclosure was numerically studied. Main attentions were focused on the effects of Reynold...A partition solution implemented by a cold air curtain for two asymmetric discrete heat sources in a twodimensional rectangular enclosure was numerically studied. Main attentions were focused on the effects of Reynolds number, Grashof number, separation distance between heat sources, and buoyancy ratio. It is found that the airflow and heat transfer are not only determined by governing parameters, but also affected by boundary conditions. It is also found that nearly symmetry of flow structure corresponds to nearly thermal partition, and the symmetry can be enhanced when Reynolds number, separation distance and buoyancy ratio increase. In addition, it is observed that there is a minimum Reynolds number for obtaining nearly thermal partition, which increases when Grashof number increases.展开更多
基金Project (200065) supported by University Key Teacher Foundation of the Ministry of Education of China
文摘Pb2+ and Cd2+ in leachate were adsorbed on clay-solidified grouting curtain for waste landfills with equilibrium experiment. The cation exchange capacity was determined with ammonium acetate. And the concentration of heavy metal cations in leachate was determined with atomic absorption spectrophotometer. Their equilibrium isotherms were measured, and the experimental isotherm data were analyzed by using Freundlich and Langmuir models. The results show that the adsorption capacities of the heavy metal cations are closely related to the compositions of clay-solidified grouting curtain, and the maximum adsorption appears at the ratio of cement to clay of 2∶4 in the experimental conditions. At their maximum adsorption and pH 5.0, the adsorption capacities of Pb 2+ and Cd 2+ are 16.19mg/g and 1.21mg/g. The competitive adsorption coefficients indicate that the adsorption of clay-solidified grouting curtain for Pb2+ is stronger than that for Cd 2+ . The adsorption process conforms to Freundlich’s model with related coefficient higher than 0.996.
基金Projects(50778145, 50278025) supported by the National Natural Science Foundation of ChinaProject(2009ZDKG-47) supported by "13115" Science and Technology Innovation Program of Shaanxi Province, China
文摘A new air distribution pattern,air curtain jet ventilation was presented.The ventilation or airflow patterns and the air velocity produced by air curtain jet were investigated in detail.To identify the airflow characteristics of this novel air curtain jet ventilation system,a full-scale room was used to measure the jet velocity with a slot-ventilated supply device,with regards to the airflow fields along the vertical wall as well as on the horizontal floor zones.The airflow fields under three supply air velocities,1.0,1.5 and 2.0 m/s,were carried out in the full-scale room.The experimental results show the velocity profiles of air distribution,the airflow fields along the attached vertical wall and the air lake zones on the floor,respectively.The current experimental research is helpful for heating,ventilation and air conditioning(HVAC) engineers to design better air distribution in rooms.
文摘The effects of components and their ratio of grouts on anti-seepage capability of clay-solidified grouting curtain and its permeability of heavy metal cations were investigated by permeating experiments, using reactive solute transport model to study the permeation of heavy metals (Cd2+, Pb2+ and Hg2+). The study of permeating for different mixture ratios of cement and clay indicates that hydraulic conductivity of clay-solidified grouting curtain with different ratios of solid to liquid or with the same ratio of solid to liquid but with different ratios of cement to clay is changed. The laboratory simulation test results also show that precipitates produced in heavy metal cation migration process in curtain block up water flowing passage which makes the hydraulic conductivity of the solution-permeated curtain decrease with the leakage time. The permeation velocities for different heavy metal cations vary with ionic concentration, exchange capacity and ion radius etc. The test results indicate that the permeation rapidity order of heavy metals cations in clay-solidified grouting curtain is Hg2+>Pb2+ in the same experimental circumstance. In addition, permeability for different mixture ratios and antisepsis capabilities of clay-solidified grouting curtain were studied in tests.
基金Project(40802064) supported by the National Natural Science Foundation of ChinaProject(Z110805) supported by the Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences Project(200925) supported by the Progress and Innovation Fund for the Transportation Science and Technology of Hunan Province,China
文摘Batch experiments were conducted to study the adsorption of phenol on clay-solidified grouting curtain (CSGC) and the effects of contact time,pH and adsorbent concentration on the adsorption were investigated.Under the experimental conditions used,2 d was adequate to determine the equilibrium of phenol adsorption onto CSGC.The amount of phenol adsorbed by CSGC from an initial concentration of 100mg/L was found to be 8.4mg/g.The adsorption process includes particle diffusion and liquid film diffusion,and the latter is the predominating step of the adsorption process.The adsorption ability of CSGC decreased with pH but it increased non-linearly with the CSGC concentration.The optimized concentration for CSGC was found to be 20g/L for the adsorption of 100mg/L phenol.
基金Project(50139030) supported by the National Natural Science Foundation of ChinaProject(501072) supported by the Scientific Research Foundation for the Returned Overseas Scholars of the Ministry of Education of China
文摘The seepage under a dam foundation is mainly controlled by the performance of the curtain.Its anti-seepage behavior may be weakened by the long term physic-chemical actions from groundwater.According to seepage hydraulics and geochemistry theory,a coupling model for assessing the behavior of the curtain under a dam foundation is set up,which consists of seepage module,solute transport module,geochemistry module and curtain erosion module,solved by FEM.A case study was carried out.The result shows that the curtain efficiency is weakened all the time.Aqueous calcium from the curtain is always in dissolution during the stress period for simulation,which leads to the increasing amount in groundwater reaching 846.35-865.312 g/m3.Within the domain,reaction extent differs in different parts of the curtain.The dissolution of Ca(OH)2 accounts to 877.884 g/m3 near the bottom and is much higher than that of the other parts.The erosion is much more serious near the bottom of the curtain than the other parts,which is the same to the upstream and downstream.Calcium dissolution is mainly controlled by hydraulic condition and dispersion,and it varies in a non-linear way within the domain.
文摘Clay-solidified grouting curtains are commonly used for remediation by containment or pollution prevention, in addition to their use as a barrier to water flow in municipal solid waste(MSW) landfills. A hydrological model.of water flow and a hydrodynamic model of contaminant are presented to simulate the migration of leachate through clay-solidified grouting curtain in MSW landfills, with particular attention paid to the role of diffusive and adsorptive fluxes in contaminant transport. The models were applied to simulate the sensitivity of the curtain's behavior to changes in parameters, such as thickness, depth, permeability coefficient, diffusion coefficient,resistance coefficient and concentration, and also to demonstrate the contaminant distribution on the evolution of travel time and offset distance of clay-solidified grouting curtain in landfills. It is found that a part of leachate components stays or is retarded in clay-solidified grouting curtain by precipitate or exchange, the retention rate is closely related to composition of clay-solidified grouting curtain, more than 800%, and the maximum occurs at the cementclay ratio of 2: 4 under experimental conditions. Contamination distribution is variable on travel time and offset distance, the highest concentration takes place where the contamination intensity is nearest to the pollution resource or takes place at early middle period of transport, and the pollutant attenuates gradually. The results indicate that claysolidified grouting curtain with a proper thickness, a low permeability coefficient and a high resistance coefficient might serve as a sufficiently effective vertical barrier against leachate seepage and contamination migration in MSWlandfills.
文摘The present problem of mining of narrow and gentle dip vein was analyzed. A new technique of rapidly following curtain filling was put forward. The results show that the new technique is feasible, has the characteristic to make the whole curtain wall filter, makes relative density of the filling tailings slurry reach saturation of 78.0% 80.0% in 25 min, and keeps the roof of mined out space stable in 60 min. The new technique of the rapidly following curtain filling has solved the difficult problem of the filling body filtering slowly and promptly controlling underground pressure, which cannot be solved in traditional ways.
基金Project (50408019) supported by the National Natural Science Foundation of China
文摘A partition solution implemented by a cold air curtain for two asymmetric discrete heat sources in a twodimensional rectangular enclosure was numerically studied. Main attentions were focused on the effects of Reynolds number, Grashof number, separation distance between heat sources, and buoyancy ratio. It is found that the airflow and heat transfer are not only determined by governing parameters, but also affected by boundary conditions. It is also found that nearly symmetry of flow structure corresponds to nearly thermal partition, and the symmetry can be enhanced when Reynolds number, separation distance and buoyancy ratio increase. In addition, it is observed that there is a minimum Reynolds number for obtaining nearly thermal partition, which increases when Grashof number increases.
