It is well-known that a close link exists between soil-water retention curve(SWRC)and pore size distribution(PSD).Theoretically,mercury intrusion porosimetry(MIP)test simulates a soil drying path and the test results ...It is well-known that a close link exists between soil-water retention curve(SWRC)and pore size distribution(PSD).Theoretically,mercury intrusion porosimetry(MIP)test simulates a soil drying path and the test results can be used to deduce the SWRC(termed SWRCMIP).However,SWRCMIP does not include the effect of volume change,compared with the conventional SWRC that is directly determined by suction measurement or suction control techniques.For deformable soils,there is a significant difference between conventional SWRC and SWRCMIP.In this study,drying test was carried out on a reconstituted silty soil,and the volume change,suction,and PSD were measured on samples with different water contents.The change in the deduced SWRCMIP and its relationship with the conventional SWRC were analyzed.The results showed that the volume change of soil is the main reason accounting for the difference between conventional SWRC and SWRCMIP.Based on the test results,a transformation model was then proposed for conventional SWRC and SWRCMIP,for which the soil state with no volume change is taken as a reference.Comparison between the experimental and predicted SWRCs showed that the proposed model can well consider the influence of soil volume change on its water retention property.展开更多
Mercury intrusion porosimetry(MIP)is a simple and fast way to obtain the pore distribution of soil and can be used to estimate the soil-water characteristic curve(SWCC).In previous studies,soil was assumed to be a per...Mercury intrusion porosimetry(MIP)is a simple and fast way to obtain the pore distribution of soil and can be used to estimate the soil-water characteristic curve(SWCC).In previous studies,soil was assumed to be a perfect wettability material,and the contact angle(CA)of the soil-water interface was taken as zero in the SWCC prediction method.However,the CA has proved to be much greater than zero even for hydrophilic soils according to some soil wettability experiments,and it has a significant effect on predicting the SWCC.In this research,a method for predicting the SWCC by MIP,which takes the CA as a fitting coefficient,is proposed.The pore size distribution curves are measured by MIP,and the SWCCs of two loess soils are measured by pressure plate and filter paper tests.When the CA is taken as70°and 50°for the wetting and drying process,respectively,the SWCCs predicted by the pore size distribution curves agree well with the measured SWCCs.The predicted suction range of the proposed method is 0-105 k Pa.The consistency of the results suggests that utilizing the MIP test to predict the SWCC with a proper CA is effective for loess.展开更多
The soil-water retention curve(SWRC)can be used to evaluate the ability of unsaturated soils to attract water at various water contents and suctions. In this study, drying SWRCs for a kind of sandy soil were obtained ...The soil-water retention curve(SWRC)can be used to evaluate the ability of unsaturated soils to attract water at various water contents and suctions. In this study, drying SWRCs for a kind of sandy soil were obtained in the laboratory by using self-modified SWRC apparatus. In addition, the porosity and the pore size distribution of the samples were investigated by a mercury porosimetry test in order to analyze the effect of dry density. Results showed that the soil-water retention of the soil specimens was strongly dependent on the dry density. Under zero suction, soil specimens with a higher dry density exhibited lower initial volumetric water content. The higher the dry density of soil, the more slowly the volumetric water content decreased with the increase of suction. There was a general and consistent trend for a soil specimen to possess a larger air-entry value and residual suction, while smaller slope of SWRC when it had a higher density. This was probably attributed to the presence of smaller interconnected pores in the soil specimen with a higher dry density. The proportion of large diameter pores decreased in comparison to pores with small diameters in the soil tested. The measured total pore volume of the soil specimen, which had a larger dry density, was lower than that of the relatively loose specimens.展开更多
The material composition and microstructure have a comprehensive influence on geological engineering properties of dredger fill.The porosity of the dredger fill is an important characteristic of microscopic structure....The material composition and microstructure have a comprehensive influence on geological engineering properties of dredger fill.The porosity of the dredger fill is an important characteristic of microscopic structure.Taken dredger fill from Binhai New Area in Tianjin as research object,the distribution trend of pore is obtained by granularmetric analysis,mineral composition analysis and mercury intrusion method.By discussing the variation regulation of dredger fill in two different kinds of processing methods,certain theoretical basis is provided for evaluating the engineering geological properties of dredger fill.It can be concluded from the test results that after drainage treatment,the porosity decreased and the structure unit changed from the relatively loose state to aggregate state.In certain depth range,the consolidation effect of dredger fill with drainage treatment is better than that without drainage treatment.展开更多
Fallout volcanic deposits of SommaVesuvius(Campania,southern Italy),characterized by the presence of layers with contrasting textural and hydraulic properties,are frequently affected by shallow landslides during rainw...Fallout volcanic deposits of SommaVesuvius(Campania,southern Italy),characterized by the presence of layers with contrasting textural and hydraulic properties,are frequently affected by shallow landslides during rainwater infiltration.The soils of the stratigraphic sequence present intraparticle pores,originated by the gases escaped during magma decompression in the volcanic conduit,thus are characterized by double porosity(i.e.,intraparticle and interparticle pores),which is expected to affect their hydraulic behaviour,and to play a key role in rainwater infiltration through layered deposits.To understand the effect of double porosity on the hydraulic behaviour of the involved soils,controlled experiments have been carried out in an infiltration column.The experimental apparatus is provided with newly designed non-invasive Time Domain Reflectometry(TDR)probes,not buried in the investigated soil layers so as to minimize disturbance to the flow,allowing water content measurement during vertical flow processes.Specifically,transient flow experiments are carried out through reconstituted specimens of black scoriae and grey pumices,both loose pyroclastic granular soils from fallout deposits of Somma-Vesuvius,featuring double porosity with different pore size distributions,that were estimated by X-ray tomography and Mercury Intrusion Porosimetry.The experimental results highlight the effects of the double porosity and clearly indicate the different behaviour of the two soils during wetting and drying processes,mainly related to the different dimensions of intraparticle pores.展开更多
Air pollution control devices(APCDs) are installed at coal-fired power plants for air pollutant regulation.Selective catalytic reduction(SCR) and wet flue gas desulfurization(FGD) systems have the co-benefits of air p...Air pollution control devices(APCDs) are installed at coal-fired power plants for air pollutant regulation.Selective catalytic reduction(SCR) and wet flue gas desulfurization(FGD) systems have the co-benefits of air pollutant and mercury removal.Configuration and operational conditions of APCDs and mercury speciation affect mercury removal efficiently at coal-fired utilities.The Ontario Hydro Method(OHM) recommended by the U.S.Environmental Protection Agency(EPA) was used to determine mercury speciation simultaneously at five sampling locations through SCR-ESP-FGD at a 190 MW unit.Chlorine in coal had been suggested as a factor affecting the mercury speciation in flue gas;and low-chlorine coal was purported to produce less oxidized mercury(Hg2+) and more elemental mercury(Hg0 ) at the SCR inlet compared to higher chlorine coal.SCR could oxidize elemental mercury into oxidized mercury when SCR was in service,and oxidation efficiency reached 71.0%.Therefore,oxidized mercury removal efficiency was enhanced through a wet FGD system.In the non-ozone season,about 89.5%-96.8% of oxidized mercury was controlled,but only 54.9%-68.8% of the total mercury was captured through wet FGD.Oxidized mercury removal efficiency was 95.9%-98.0%,and there was a big difference in the total mercury removal efficiencies from 78.0% to 90.2% in the ozone season.Mercury mass balance was evaluated to validate reliability of OHM testing data,and the ratio of mercury input in the coal to mercury output at the stack was from 0.84 to 1.08.展开更多
The Ontario Hydro Method (OHM) recommended by the United States EnvironmentalProtection Agency (EPA) was used to determine mercury speciation in the combustionflue gas across wet FGD systems.Four coal-fired units with...The Ontario Hydro Method (OHM) recommended by the United States EnvironmentalProtection Agency (EPA) was used to determine mercury speciation in the combustionflue gas across wet FGD systems.Four coal-fired units with wet FGD systemswere chosen to evaluate mercury speciation and mercury removal efficiencies throughthese wet FGD systems.Chlorine content in coal had been suggested as a main factorthat affects mercury speciation in flue gas.It is shown that the higher the chlorine concentrationin coal is, the higher the percentage of oxidized mercury (Hg^(2+)) is removed in wetFGD systems, which can increase overall mercury removal efficiencies through wet FGDsystems.The selective catalyst reduction (SCR) system has a function of oxidizing elementalmercury (Hg^0) to oxidized mercury.A higher percentage of oxidized mercury in thetotal vapor mercury at the FGD inlet is observed when SCR is in service.Therefore, higheroverall mercury removal efficiencies through wet FGD are attained.Because of differentwet FGD operating conditions, there are different mercury removal efficiencies in differentunits.Elemental mercury reemission took place when a fraction of oxidized mercury absorbedin the slurry is reduced to elemental mercury, and Hg^0 is reemitted from stack,which results in decreases in mercury removal efficiencies through wet FGD systems.展开更多
The study investigated residual effects of high levels of occupational mercury exposure, 30 years after a cohort of women worked in public service dentistry. They had all used copper amalgam in a pellet form that requ...The study investigated residual effects of high levels of occupational mercury exposure, 30 years after a cohort of women worked in public service dentistry. They had all used copper amalgam in a pellet form that required heating and handling, and silver amalgam before the encapsulated form was available. Mercury handling practices changed in the mid-1970 when the workforce was urine tested and mercury poisoning became apparent. The aim was to compare control group and exposed group scores on tasks from a neurobehavioural test battery;plus survey results from a composite health, work history and environmental influences survey. The findings showed that the exposed and control groups were equivalent not only on those variables that one would want to be matched (age, alcohol consumption), but also on many of the cognitive and psychomotor test scores. The present paper focuses on psychomotor skill and tremor patterns. Tremor patterns were seen as generating new evidence of long term effects of the historic mercury insult. Data also suggest that there may be a distinctive mercury “fingerprint”, in samples of sinusoidal waveforms that may have potential as a non-invasive sub-clinical biomarker for adverse effects of mercury exposure, in screening or workplace monitoring.展开更多
基金Shanghai Key Innovative Team of Cultural Heritage Conservation and the financial support from the National Sciences Foundation of China(Grant Nos.41977214 and 41572284)the Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences(Grant No.Z013008)。
文摘It is well-known that a close link exists between soil-water retention curve(SWRC)and pore size distribution(PSD).Theoretically,mercury intrusion porosimetry(MIP)test simulates a soil drying path and the test results can be used to deduce the SWRC(termed SWRCMIP).However,SWRCMIP does not include the effect of volume change,compared with the conventional SWRC that is directly determined by suction measurement or suction control techniques.For deformable soils,there is a significant difference between conventional SWRC and SWRCMIP.In this study,drying test was carried out on a reconstituted silty soil,and the volume change,suction,and PSD were measured on samples with different water contents.The change in the deduced SWRCMIP and its relationship with the conventional SWRC were analyzed.The results showed that the volume change of soil is the main reason accounting for the difference between conventional SWRC and SWRCMIP.Based on the test results,a transformation model was then proposed for conventional SWRC and SWRCMIP,for which the soil state with no volume change is taken as a reference.Comparison between the experimental and predicted SWRCs showed that the proposed model can well consider the influence of soil volume change on its water retention property.
基金supported by the National Natural Science Foundation of China(Program No.41790442 and No.41772278)。
文摘Mercury intrusion porosimetry(MIP)is a simple and fast way to obtain the pore distribution of soil and can be used to estimate the soil-water characteristic curve(SWCC).In previous studies,soil was assumed to be a perfect wettability material,and the contact angle(CA)of the soil-water interface was taken as zero in the SWCC prediction method.However,the CA has proved to be much greater than zero even for hydrophilic soils according to some soil wettability experiments,and it has a significant effect on predicting the SWCC.In this research,a method for predicting the SWCC by MIP,which takes the CA as a fitting coefficient,is proposed.The pore size distribution curves are measured by MIP,and the SWCCs of two loess soils are measured by pressure plate and filter paper tests.When the CA is taken as70°and 50°for the wetting and drying process,respectively,the SWCCs predicted by the pore size distribution curves agree well with the measured SWCCs.The predicted suction range of the proposed method is 0-105 k Pa.The consistency of the results suggests that utilizing the MIP test to predict the SWCC with a proper CA is effective for loess.
基金Supported by the National Natural Science Foundation of China(No.51409261)
文摘The soil-water retention curve(SWRC)can be used to evaluate the ability of unsaturated soils to attract water at various water contents and suctions. In this study, drying SWRCs for a kind of sandy soil were obtained in the laboratory by using self-modified SWRC apparatus. In addition, the porosity and the pore size distribution of the samples were investigated by a mercury porosimetry test in order to analyze the effect of dry density. Results showed that the soil-water retention of the soil specimens was strongly dependent on the dry density. Under zero suction, soil specimens with a higher dry density exhibited lower initial volumetric water content. The higher the dry density of soil, the more slowly the volumetric water content decreased with the increase of suction. There was a general and consistent trend for a soil specimen to possess a larger air-entry value and residual suction, while smaller slope of SWRC when it had a higher density. This was probably attributed to the presence of smaller interconnected pores in the soil specimen with a higher dry density. The proportion of large diameter pores decreased in comparison to pores with small diameters in the soil tested. The measured total pore volume of the soil specimen, which had a larger dry density, was lower than that of the relatively loose specimens.
文摘The material composition and microstructure have a comprehensive influence on geological engineering properties of dredger fill.The porosity of the dredger fill is an important characteristic of microscopic structure.Taken dredger fill from Binhai New Area in Tianjin as research object,the distribution trend of pore is obtained by granularmetric analysis,mineral composition analysis and mercury intrusion method.By discussing the variation regulation of dredger fill in two different kinds of processing methods,certain theoretical basis is provided for evaluating the engineering geological properties of dredger fill.It can be concluded from the test results that after drainage treatment,the porosity decreased and the structure unit changed from the relatively loose state to aggregate state.In certain depth range,the consolidation effect of dredger fill with drainage treatment is better than that without drainage treatment.
文摘Fallout volcanic deposits of SommaVesuvius(Campania,southern Italy),characterized by the presence of layers with contrasting textural and hydraulic properties,are frequently affected by shallow landslides during rainwater infiltration.The soils of the stratigraphic sequence present intraparticle pores,originated by the gases escaped during magma decompression in the volcanic conduit,thus are characterized by double porosity(i.e.,intraparticle and interparticle pores),which is expected to affect their hydraulic behaviour,and to play a key role in rainwater infiltration through layered deposits.To understand the effect of double porosity on the hydraulic behaviour of the involved soils,controlled experiments have been carried out in an infiltration column.The experimental apparatus is provided with newly designed non-invasive Time Domain Reflectometry(TDR)probes,not buried in the investigated soil layers so as to minimize disturbance to the flow,allowing water content measurement during vertical flow processes.Specifically,transient flow experiments are carried out through reconstituted specimens of black scoriae and grey pumices,both loose pyroclastic granular soils from fallout deposits of Somma-Vesuvius,featuring double porosity with different pore size distributions,that were estimated by X-ray tomography and Mercury Intrusion Porosimetry.The experimental results highlight the effects of the double porosity and clearly indicate the different behaviour of the two soils during wetting and drying processes,mainly related to the different dimensions of intraparticle pores.
基金supported by the U.S.Agency for International Development (USAID) cooperation agreement(No.486-A-00-06-000140-00)
文摘Air pollution control devices(APCDs) are installed at coal-fired power plants for air pollutant regulation.Selective catalytic reduction(SCR) and wet flue gas desulfurization(FGD) systems have the co-benefits of air pollutant and mercury removal.Configuration and operational conditions of APCDs and mercury speciation affect mercury removal efficiently at coal-fired utilities.The Ontario Hydro Method(OHM) recommended by the U.S.Environmental Protection Agency(EPA) was used to determine mercury speciation simultaneously at five sampling locations through SCR-ESP-FGD at a 190 MW unit.Chlorine in coal had been suggested as a factor affecting the mercury speciation in flue gas;and low-chlorine coal was purported to produce less oxidized mercury(Hg2+) and more elemental mercury(Hg0 ) at the SCR inlet compared to higher chlorine coal.SCR could oxidize elemental mercury into oxidized mercury when SCR was in service,and oxidation efficiency reached 71.0%.Therefore,oxidized mercury removal efficiency was enhanced through a wet FGD system.In the non-ozone season,about 89.5%-96.8% of oxidized mercury was controlled,but only 54.9%-68.8% of the total mercury was captured through wet FGD.Oxidized mercury removal efficiency was 95.9%-98.0%,and there was a big difference in the total mercury removal efficiencies from 78.0% to 90.2% in the ozone season.Mercury mass balance was evaluated to validate reliability of OHM testing data,and the ratio of mercury input in the coal to mercury output at the stack was from 0.84 to 1.08.
文摘The Ontario Hydro Method (OHM) recommended by the United States EnvironmentalProtection Agency (EPA) was used to determine mercury speciation in the combustionflue gas across wet FGD systems.Four coal-fired units with wet FGD systemswere chosen to evaluate mercury speciation and mercury removal efficiencies throughthese wet FGD systems.Chlorine content in coal had been suggested as a main factorthat affects mercury speciation in flue gas.It is shown that the higher the chlorine concentrationin coal is, the higher the percentage of oxidized mercury (Hg^(2+)) is removed in wetFGD systems, which can increase overall mercury removal efficiencies through wet FGDsystems.The selective catalyst reduction (SCR) system has a function of oxidizing elementalmercury (Hg^0) to oxidized mercury.A higher percentage of oxidized mercury in thetotal vapor mercury at the FGD inlet is observed when SCR is in service.Therefore, higheroverall mercury removal efficiencies through wet FGD are attained.Because of differentwet FGD operating conditions, there are different mercury removal efficiencies in differentunits.Elemental mercury reemission took place when a fraction of oxidized mercury absorbedin the slurry is reduced to elemental mercury, and Hg^0 is reemitted from stack,which results in decreases in mercury removal efficiencies through wet FGD systems.
文摘The study investigated residual effects of high levels of occupational mercury exposure, 30 years after a cohort of women worked in public service dentistry. They had all used copper amalgam in a pellet form that required heating and handling, and silver amalgam before the encapsulated form was available. Mercury handling practices changed in the mid-1970 when the workforce was urine tested and mercury poisoning became apparent. The aim was to compare control group and exposed group scores on tasks from a neurobehavioural test battery;plus survey results from a composite health, work history and environmental influences survey. The findings showed that the exposed and control groups were equivalent not only on those variables that one would want to be matched (age, alcohol consumption), but also on many of the cognitive and psychomotor test scores. The present paper focuses on psychomotor skill and tremor patterns. Tremor patterns were seen as generating new evidence of long term effects of the historic mercury insult. Data also suggest that there may be a distinctive mercury “fingerprint”, in samples of sinusoidal waveforms that may have potential as a non-invasive sub-clinical biomarker for adverse effects of mercury exposure, in screening or workplace monitoring.
