Alkaline water electrolysis(AWE)is the most mature technology for hydrogen production by water electrolysis.Alkaline water electrolyzer consists of multiple electrolysis cells,and a single cell consists of a diaphragm...Alkaline water electrolysis(AWE)is the most mature technology for hydrogen production by water electrolysis.Alkaline water electrolyzer consists of multiple electrolysis cells,and a single cell consists of a diaphragm,electrodes,bipolar plates and end plates,etc.The existing industrial bipolar plate channel is concave-convex structure,which is manufactured by complicated and high-cost mold punching.This structure still results in uneven electrolyte flow and low current density in the electrolytic cell,further increasing in energy consumption and cost of AWE.Thereby,in this article,the electrochemical and flow model is firstly constructed,based on the existing industrial concave and convex flow channel structure of bipolar plate,to study the current density,electrolyte flow and bubble distribution in the electrolysis cell.The reliability of the model was verified by comparison with experimental data in literature.Among which,the electrochemical current density affects the bubble yield,on the other hand,the generated bubbles cover the electrode surface,affecting the active specific surface area and ohmic resistance,which in turn affects the electrochemical reaction.The result indicates that the flow velocity near the bottom of the concave ball approaches zero,while the flow velocity on the convex ball surface is significantly higher.Additionally,vortices are observed within the flow channel structure,leading to an uneven distribution of electrolyte.Next,modelling is used to optimize the bipolar plate structure of AWE by simulating the electrochemistry and fluid flow performances of four kinds of structures,namely,concave and convex,rhombus,wedge and expanded mesh,in the bipolar plate of alkaline water electrolyzer.The results show that the expanded mesh channel structure has the largest current density of 3330 A/m^(2)and electrolyte flow velocity of 0.507 m/s in the electrolytic cell.Under the same current density,the electrolytic cell with the expanded mesh runner structure has the smallest potential and energy consumption.This work provides a useful guide for the comprehensive understanding and optimization of channel structures,and a theoretical basis for the design of large-scale electrolyzer.展开更多
基于Web of Science平台的SCI—EXPANDED数据库，采用文献计量学方法，以世界和中国发表于1995—2013年的大豆相关研究论文为检索对象，分析了不同国家、机构、作者和期刊的论文数目及引用频次、学科分布和论文语种等情况。借助CiteSpac...基于Web of Science平台的SCI—EXPANDED数据库，采用文献计量学方法，以世界和中国发表于1995—2013年的大豆相关研究论文为检索对象，分析了不同国家、机构、作者和期刊的论文数目及引用频次、学科分布和论文语种等情况。借助CiteSpaceⅢ信息可视化软件绘制大豆研究的科学知识图谱，直观地展示和分析了大豆研究的知识基础和前沿领域。结果表明：1995—2013年SCI—EXPANDED数据库共收录17576篇大豆相关研究论文，发文的36190位作者来自122个国家的5879个机构。论文数目呈波动增长态势，美国、巴西、中国、日本和韩国大豆相关研究论文数目居前5位；美国农业部所属机构、艾奥瓦州立大学和伊利诺伊大学等机构的论文质量较高。发表大豆相关论文数目位居世界前5位的作者为美国科学家Hartman G L、Shoemaker R C、Boerma H R、Nelson R L和加拿大科学家Cober E R。载文量排名前5位的期刊分别是Crop Science、Journal of Agricultural and Food Chemistry、Journal of the American Oil Chemists Society、Agronomy Journal和Pesquisa Agropecuaria Brasileira。论文主要集中在植物学、农艺学、食品科学和技术、农业一跨学科、应用化学、生物化学和和分子生物学等学科。大豆分子生物学、植物保护、遗传育种、加工和品质、转基因技术、豆粕饲料和生物柴油研究是世界大豆研究的前沿领域。中国大豆研究的整体规模和水平均已位于世界前列，但在国际高影响力刊物上发表的论文数量还不多，国际影响力有待进一步提升。展开更多
A binary eutectic mixture composed of tetradecanol(TD)and myristic acid(MA)was maximally absorbed into the microstructures of expanded perlite(EP)and expanded vermiculite(EVMT),respectively,through a self-made vacuum ...A binary eutectic mixture composed of tetradecanol(TD)and myristic acid(MA)was maximally absorbed into the microstructures of expanded perlite(EP)and expanded vermiculite(EVMT),respectively,through a self-made vacuum adsorption roller to prepare phase change material(PCM)particle(PCP).Then EP and EVMT-based composite PCM plates were respectively fabricated through a mold pressing method.The thermal property,chemical stability,microstructure and durability were characterized by differential scanning calorimeter(DSC),Fourier transform infrared spectroscope(FT-IR),scanning electron microscope(SEM)and thermal cycling tests,respectively.The results show that both PCPs have high latent heats with 110 J/g for EP-based PCP and more than 130 J/g for EVMT-based PCP,compact microstructure without PCM leakage,stable chemical property and good durability.The research results have proved the feasibility for the vacuum adsorption roller used in the composite PCM fabrication.Results of thermal storage performance experiment indicate that the fabricated PCM plates have better thermal inertia than common building materials,and the thermal storage performance of PCM plates has nonlinearly changed with outside air velocity and temperature increase.Therefore,PCM plates show a significant potential for the practical application of building thermal storage.展开更多
Phase change material(PCM)can reduce the indoor temperature fluctuation and humidity control material can adjust relative humidity used in buildings.In this study,a kind of composite phase change material particles(CP...Phase change material(PCM)can reduce the indoor temperature fluctuation and humidity control material can adjust relative humidity used in buildings.In this study,a kind of composite phase change material particles(CPCMPs)were prepared by vacuum impregnation method with expanded perlite(EP)as supporting material and paraffin as phase change material.Thus,a PCM plate was fabricated by mould pressing method with CPCMPs and then composite phase change humidity control wallboard(CPCHCW)was prepared by spraying the diatom mud on the surface of PCM plate.The composition,thermophysical properties and microstructure were characterized using X-ray diffraction instrument(XRD),differential scanning calorimeter(DSC)and scanning electron microscope(SEM).Additionally,the hygrothermal performance of CPCHCW was characterized by temperature and humidity collaborative test.The results can be summarized as follows:(1)CPCMPs have suitable phase change parameters with melting/freezing point of 18.23°C/29.42°C and higher latent heat of 54.66 J/g/55.63 J/g;(2)the diatom mud can control the humidity of confined space with a certain volume;(3)the combination of diatom mud and PCM plate in CPCHCW can effectively adjust the indoor temperature and humidity.The above conclusions indicate the potential of CPCHCW in the application of building energy efficiency.展开更多
Through direct shear and triaxial compression tests, effects of expanded polystyrene (EPS) mass ratios in sand-EPS mixtures and stress status on materials' shear behavior were investigated. Hyperbolic curves were ...Through direct shear and triaxial compression tests, effects of expanded polystyrene (EPS) mass ratios in sand-EPS mixtures and stress status on materials' shear behavior were investigated. Hyperbolic curves were used to fit relationship between shear stress and shear displacement. The shear behavior is marginally associated with the EPS ratios and normal/confining stresses. Increases of EPS ratios and decreases of normal/confining stresses result in shear strength decreases. The shapes of Mohr-Coulomb's envelope include linear and piecewise linear types, which are basically determined by the EPS ratio. Such difference is thought related to the embedding or apparent cohesion effect under relatively high EPS ratio conditions. Shear strength parameters can be used for further modeling and design purposes.展开更多
Expanded bed adsorption (EBA) has been introduced as a primary recovery step for protein purification from a whole fermentation broth or unclarified cell homogenates. It can also be integrated with a fermentation or c...Expanded bed adsorption (EBA) has been introduced as a primary recovery step for protein purification from a whole fermentation broth or unclarified cell homogenates. It can also be integrated with a fermentation or cell disruption process. Solid matrix is the principal pillar supporting the successful application of the EBA technology. This article summarizes the solid matrices employed in and developed for the EBA process to date. Further development of solid matrices for the expanded bed technique in the recovery of various biological substances from different sources has been addressed.展开更多
Deformation characteristics of light weight soil with different EPS (expanded polystyrene) sizes were investigated by consolidation tests.The results show that the confined stress-strain relation curve is in S shape,w...Deformation characteristics of light weight soil with different EPS (expanded polystyrene) sizes were investigated by consolidation tests.The results show that the confined stress-strain relation curve is in S shape,which has a good homologous relation with e-p curve and e-lgp curve,and three types of curves reflect obvious structural characteristics of light weight soil.When cement mixed ratio and EPS volume ratio are the same for different specimens,structural strength decreases with the increase of EPS size,but compressibility indexes basically keep unchanged within the structural strength.The settlement of light weight soil can be divided into instantaneous settlement and primary consolidation settlement.It has no obvious rheology property,and 90% of total consolidation deformation can be finished in 1 min.Settlement-time relation of light weight soil can be predicted by the hyperbolic model.S-lgt curve of light weight soil is not in anti-S shape.It is proved that there is no secondary consolidation section,so consolidation coefficient cannot be obtained by time logarithm method.Structural strength and unit price decrease with the increase of EPS size,but the reducing rate of the structural strength is lower than that of the unit price,so the cost of mixed soil can be reduced by increasing the EPS size.The EPS beads with 3-5 mm in diameter are suggested to be used in the construction process,and the prescription of mixed soil can be optimized.展开更多
By using hydrothermal synthesis method, successively adding tetrabutyl titanate and expandable flake graphite in 40 mL 0.95% NH4Cl solution prepared the nano TiO2/expandable flake graphite, which was then settled in m...By using hydrothermal synthesis method, successively adding tetrabutyl titanate and expandable flake graphite in 40 mL 0.95% NH4Cl solution prepared the nano TiO2/expandable flake graphite, which was then settled in muffle furnace in the expansion of 10 s under 800 ℃ and got nanosized TiO2/expanded graphite. Synthesized that with CoFe2O4 by chemical coprecipitation method finally prepared magnetic nanosized photocatalyst TiO2/expanded graphite. Magnetic nanosized TiO2/expanded graphite was studied on the photodegradation performance of methyl orange solution and the magnetic recovery after the degradation of methyl orange solution. The experiment result showed that in 50 mL 25 mg/L methyl orange solution joined 120 mg loading 50% TiO2 of the expanded graphite, exposed to ultraviolet irradiation for 1 h, the methyl orange decolorization ratio was 90%. When the load of CoFe2O4 in nanosized TiO2/expanded graphite reached 40%, its magnetic recovery efficiency reached 94.3%.展开更多
The expanded graphite (EG) with a low density and better extinction performance can be used in military as passive jamming material in IR and MMW bands. Its complex refractive index is a significant parameter for the ...The expanded graphite (EG) with a low density and better extinction performance can be used in military as passive jamming material in IR and MMW bands. Its complex refractive index is a significant parameter for the extinction property. This paper presents a method to calculate the complex refractive index of EG. The reflection spectra of EG pellets were measured in the 0.24-2.6μm and 2.5-25μm bands, respectively. Based on the measurement results, the complex refractive index of EG in 5-10μm band was calculated by using Kramers-Kronig(K-K) relation and Bruggeman effective medium theory, and then the errors were analyzed. The results indicate that it is feasible to calculate the complex refractive index of EG based on its IR reflection spectra data.展开更多
When an expanded-base pile is installed into ground, the cavity expansion associated with penetration of the enlarged pile base is followed by cavity contraction along the smaller-diameter pile shaft. In order to acco...When an expanded-base pile is installed into ground, the cavity expansion associated with penetration of the enlarged pile base is followed by cavity contraction along the smaller-diameter pile shaft. In order to account for the influence of cavity contraction on the change of bearing capacity of expanded-base pile, a theoretical calculation methodology, predicting the setup of expanded-base pile, was established by employing the cavity contraction theory to estimate the shaft resistance of expanded-base pile, and horizontal consolidation theory to predict the dissipation of excess pore pressure. Finally, the numerical solutions for the setup of expanded-base pile were obtained. The parametric study about the influence of cavity contraction on setup of expanded-base pile was carried out, while a field test was introduced. The parametric study shows that the decrements in radial pressure and the maximum pore water pressure after considering cavity contraction are increased as the expanded ratio(base diameter/shaft diameter) and rigidity index of soil are raised. The comparison between calculated and measured values shows that the calculated results of ultimate bearing capacity for expanded-base pile considering cavity contraction agree well with the measured values; however, the computations ignoring cavity contraction are 2.5-3.0 times the measured values.展开更多
The expanded ammonium nitrate (EAN) samples with different states were prepared by using a vacuum crystallizing technology. The structure characters,such as porosity,pore structure,specific surface area,particle surfa...The expanded ammonium nitrate (EAN) samples with different states were prepared by using a vacuum crystallizing technology. The structure characters,such as porosity,pore structure,specific surface area,particle surface shape and surface defects,and detonator initiation sensitivity and explosion power,of common ammonium nitrate (AN) and EAN were tested using density measuring,N2 adsorbing,scanning electron microscope (SEM) and plate trace test methods. The tested results show that the particle surface of common AN is smoother,denser,lower porosity and specific surface area than those tested of EAN. The particle surface of EAN is irregular,which has edges,protuberance and severely distorted crystal form,and its specific surface area and porosity are larger than those of un-expanded AN. EAN has typical self-sensitization structure characters. The detonator initiation sensitivity and explosion power of ammonium nitrate-fuel oil(ANFO) made of different states of EAN are related to the self-sensitization structures of EAN,and expanded ANFO sample has higher detonator initiation sensitivity and explosion power compared with un-expanded ANFO sample. The characterization techniques can be used to reveal the self-sensitization structure of EAN.展开更多
基金financially supported by the National Natural Science Foundation of China(No.52074130)the Engineering Research Center of Resource Utilization of Carbon-containing Waste with Carbon Neutrality,Ministry of Education。
文摘Alkaline water electrolysis(AWE)is the most mature technology for hydrogen production by water electrolysis.Alkaline water electrolyzer consists of multiple electrolysis cells,and a single cell consists of a diaphragm,electrodes,bipolar plates and end plates,etc.The existing industrial bipolar plate channel is concave-convex structure,which is manufactured by complicated and high-cost mold punching.This structure still results in uneven electrolyte flow and low current density in the electrolytic cell,further increasing in energy consumption and cost of AWE.Thereby,in this article,the electrochemical and flow model is firstly constructed,based on the existing industrial concave and convex flow channel structure of bipolar plate,to study the current density,electrolyte flow and bubble distribution in the electrolysis cell.The reliability of the model was verified by comparison with experimental data in literature.Among which,the electrochemical current density affects the bubble yield,on the other hand,the generated bubbles cover the electrode surface,affecting the active specific surface area and ohmic resistance,which in turn affects the electrochemical reaction.The result indicates that the flow velocity near the bottom of the concave ball approaches zero,while the flow velocity on the convex ball surface is significantly higher.Additionally,vortices are observed within the flow channel structure,leading to an uneven distribution of electrolyte.Next,modelling is used to optimize the bipolar plate structure of AWE by simulating the electrochemistry and fluid flow performances of four kinds of structures,namely,concave and convex,rhombus,wedge and expanded mesh,in the bipolar plate of alkaline water electrolyzer.The results show that the expanded mesh channel structure has the largest current density of 3330 A/m^(2)and electrolyte flow velocity of 0.507 m/s in the electrolytic cell.Under the same current density,the electrolytic cell with the expanded mesh runner structure has the smallest potential and energy consumption.This work provides a useful guide for the comprehensive understanding and optimization of channel structures,and a theoretical basis for the design of large-scale electrolyzer.
文摘基于Web of Science平台的SCI—EXPANDED数据库，采用文献计量学方法，以世界和中国发表于1995—2013年的大豆相关研究论文为检索对象，分析了不同国家、机构、作者和期刊的论文数目及引用频次、学科分布和论文语种等情况。借助CiteSpaceⅢ信息可视化软件绘制大豆研究的科学知识图谱，直观地展示和分析了大豆研究的知识基础和前沿领域。结果表明：1995—2013年SCI—EXPANDED数据库共收录17576篇大豆相关研究论文，发文的36190位作者来自122个国家的5879个机构。论文数目呈波动增长态势，美国、巴西、中国、日本和韩国大豆相关研究论文数目居前5位；美国农业部所属机构、艾奥瓦州立大学和伊利诺伊大学等机构的论文质量较高。发表大豆相关论文数目位居世界前5位的作者为美国科学家Hartman G L、Shoemaker R C、Boerma H R、Nelson R L和加拿大科学家Cober E R。载文量排名前5位的期刊分别是Crop Science、Journal of Agricultural and Food Chemistry、Journal of the American Oil Chemists Society、Agronomy Journal和Pesquisa Agropecuaria Brasileira。论文主要集中在植物学、农艺学、食品科学和技术、农业一跨学科、应用化学、生物化学和和分子生物学等学科。大豆分子生物学、植物保护、遗传育种、加工和品质、转基因技术、豆粕饲料和生物柴油研究是世界大豆研究的前沿领域。中国大豆研究的整体规模和水平均已位于世界前列，但在国际高影响力刊物上发表的论文数量还不多，国际影响力有待进一步提升。
基金Project(51408184)supported by the National Natural Science Foundation of ChinaProject(E2017202136)supported by the Natural Science Foundation of Hebei Province,China+1 种基金Project(BSBE2017-05)supported by Opening Funds of State Key Laboratory of Building Safety and Built Environment and National Engineering Research Center of Building Technology,ChinaProject(QG2018-3)supported by Hebei Provincial Department of Transportation,China
文摘A binary eutectic mixture composed of tetradecanol(TD)and myristic acid(MA)was maximally absorbed into the microstructures of expanded perlite(EP)and expanded vermiculite(EVMT),respectively,through a self-made vacuum adsorption roller to prepare phase change material(PCM)particle(PCP).Then EP and EVMT-based composite PCM plates were respectively fabricated through a mold pressing method.The thermal property,chemical stability,microstructure and durability were characterized by differential scanning calorimeter(DSC),Fourier transform infrared spectroscope(FT-IR),scanning electron microscope(SEM)and thermal cycling tests,respectively.The results show that both PCPs have high latent heats with 110 J/g for EP-based PCP and more than 130 J/g for EVMT-based PCP,compact microstructure without PCM leakage,stable chemical property and good durability.The research results have proved the feasibility for the vacuum adsorption roller used in the composite PCM fabrication.Results of thermal storage performance experiment indicate that the fabricated PCM plates have better thermal inertia than common building materials,and the thermal storage performance of PCM plates has nonlinearly changed with outside air velocity and temperature increase.Therefore,PCM plates show a significant potential for the practical application of building thermal storage.
基金Project(51408184)supported by the National Natural Science Foundation of ChinaProject(E2017202136)supported by the Natural Science Foundation of Hebei Province,China+1 种基金Project(BSBE2017-05)supported by the Opening Funds of State Key Laboratory of Building Safety and Built Environment and National Engineering Research Center of Building Technology,ChinaProject(QG2018-3)supported by Hebei Provincial Department of Transportation,China
文摘Phase change material(PCM)can reduce the indoor temperature fluctuation and humidity control material can adjust relative humidity used in buildings.In this study,a kind of composite phase change material particles(CPCMPs)were prepared by vacuum impregnation method with expanded perlite(EP)as supporting material and paraffin as phase change material.Thus,a PCM plate was fabricated by mould pressing method with CPCMPs and then composite phase change humidity control wallboard(CPCHCW)was prepared by spraying the diatom mud on the surface of PCM plate.The composition,thermophysical properties and microstructure were characterized using X-ray diffraction instrument(XRD),differential scanning calorimeter(DSC)and scanning electron microscope(SEM).Additionally,the hygrothermal performance of CPCHCW was characterized by temperature and humidity collaborative test.The results can be summarized as follows:(1)CPCMPs have suitable phase change parameters with melting/freezing point of 18.23°C/29.42°C and higher latent heat of 54.66 J/g/55.63 J/g;(2)the diatom mud can control the humidity of confined space with a certain volume;(3)the combination of diatom mud and PCM plate in CPCHCW can effectively adjust the indoor temperature and humidity.The above conclusions indicate the potential of CPCHCW in the application of building energy efficiency.
基金Project(50708031) supported by the National Natural Science Foundation of ChinaProject supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, SEM
文摘Through direct shear and triaxial compression tests, effects of expanded polystyrene (EPS) mass ratios in sand-EPS mixtures and stress status on materials' shear behavior were investigated. Hyperbolic curves were used to fit relationship between shear stress and shear displacement. The shear behavior is marginally associated with the EPS ratios and normal/confining stresses. Increases of EPS ratios and decreases of normal/confining stresses result in shear strength decreases. The shapes of Mohr-Coulomb's envelope include linear and piecewise linear types, which are basically determined by the EPS ratio. Such difference is thought related to the embedding or apparent cohesion effect under relatively high EPS ratio conditions. Shear strength parameters can be used for further modeling and design purposes.
文摘Expanded bed adsorption (EBA) has been introduced as a primary recovery step for protein purification from a whole fermentation broth or unclarified cell homogenates. It can also be integrated with a fermentation or cell disruption process. Solid matrix is the principal pillar supporting the successful application of the EBA technology. This article summarizes the solid matrices employed in and developed for the EBA process to date. Further development of solid matrices for the expanded bed technique in the recovery of various biological substances from different sources has been addressed.
基金Project(2012JQ7013)supported by the Natural Science Foundation of Shaanxi Province,ChinaProject(QN2012025)supported by the Fundamental Research Funds for the Central Universities of ChinaProject(2011BSJJ084)supported by Research Foundation of Northwest A&F University,China
文摘Deformation characteristics of light weight soil with different EPS (expanded polystyrene) sizes were investigated by consolidation tests.The results show that the confined stress-strain relation curve is in S shape,which has a good homologous relation with e-p curve and e-lgp curve,and three types of curves reflect obvious structural characteristics of light weight soil.When cement mixed ratio and EPS volume ratio are the same for different specimens,structural strength decreases with the increase of EPS size,but compressibility indexes basically keep unchanged within the structural strength.The settlement of light weight soil can be divided into instantaneous settlement and primary consolidation settlement.It has no obvious rheology property,and 90% of total consolidation deformation can be finished in 1 min.Settlement-time relation of light weight soil can be predicted by the hyperbolic model.S-lgt curve of light weight soil is not in anti-S shape.It is proved that there is no secondary consolidation section,so consolidation coefficient cannot be obtained by time logarithm method.Structural strength and unit price decrease with the increase of EPS size,but the reducing rate of the structural strength is lower than that of the unit price,so the cost of mixed soil can be reduced by increasing the EPS size.The EPS beads with 3-5 mm in diameter are suggested to be used in the construction process,and the prescription of mixed soil can be optimized.
文摘By using hydrothermal synthesis method, successively adding tetrabutyl titanate and expandable flake graphite in 40 mL 0.95% NH4Cl solution prepared the nano TiO2/expandable flake graphite, which was then settled in muffle furnace in the expansion of 10 s under 800 ℃ and got nanosized TiO2/expanded graphite. Synthesized that with CoFe2O4 by chemical coprecipitation method finally prepared magnetic nanosized photocatalyst TiO2/expanded graphite. Magnetic nanosized TiO2/expanded graphite was studied on the photodegradation performance of methyl orange solution and the magnetic recovery after the degradation of methyl orange solution. The experiment result showed that in 50 mL 25 mg/L methyl orange solution joined 120 mg loading 50% TiO2 of the expanded graphite, exposed to ultraviolet irradiation for 1 h, the methyl orange decolorization ratio was 90%. When the load of CoFe2O4 in nanosized TiO2/expanded graphite reached 40%, its magnetic recovery efficiency reached 94.3%.
文摘The expanded graphite (EG) with a low density and better extinction performance can be used in military as passive jamming material in IR and MMW bands. Its complex refractive index is a significant parameter for the extinction property. This paper presents a method to calculate the complex refractive index of EG. The reflection spectra of EG pellets were measured in the 0.24-2.6μm and 2.5-25μm bands, respectively. Based on the measurement results, the complex refractive index of EG in 5-10μm band was calculated by using Kramers-Kronig(K-K) relation and Bruggeman effective medium theory, and then the errors were analyzed. The results indicate that it is feasible to calculate the complex refractive index of EG based on its IR reflection spectra data.
基金Project(LQ15E080002)supported by Zhejiang Provincial Natural Science Foundation of ChinaProjects(5150828251478228)supported by the National Natural Science Foundation of China
文摘When an expanded-base pile is installed into ground, the cavity expansion associated with penetration of the enlarged pile base is followed by cavity contraction along the smaller-diameter pile shaft. In order to account for the influence of cavity contraction on the change of bearing capacity of expanded-base pile, a theoretical calculation methodology, predicting the setup of expanded-base pile, was established by employing the cavity contraction theory to estimate the shaft resistance of expanded-base pile, and horizontal consolidation theory to predict the dissipation of excess pore pressure. Finally, the numerical solutions for the setup of expanded-base pile were obtained. The parametric study about the influence of cavity contraction on setup of expanded-base pile was carried out, while a field test was introduced. The parametric study shows that the decrements in radial pressure and the maximum pore water pressure after considering cavity contraction are increased as the expanded ratio(base diameter/shaft diameter) and rigidity index of soil are raised. The comparison between calculated and measured values shows that the calculated results of ultimate bearing capacity for expanded-base pile considering cavity contraction agree well with the measured values; however, the computations ignoring cavity contraction are 2.5-3.0 times the measured values.
文摘The expanded ammonium nitrate (EAN) samples with different states were prepared by using a vacuum crystallizing technology. The structure characters,such as porosity,pore structure,specific surface area,particle surface shape and surface defects,and detonator initiation sensitivity and explosion power,of common ammonium nitrate (AN) and EAN were tested using density measuring,N2 adsorbing,scanning electron microscope (SEM) and plate trace test methods. The tested results show that the particle surface of common AN is smoother,denser,lower porosity and specific surface area than those tested of EAN. The particle surface of EAN is irregular,which has edges,protuberance and severely distorted crystal form,and its specific surface area and porosity are larger than those of un-expanded AN. EAN has typical self-sensitization structure characters. The detonator initiation sensitivity and explosion power of ammonium nitrate-fuel oil(ANFO) made of different states of EAN are related to the self-sensitization structures of EAN,and expanded ANFO sample has higher detonator initiation sensitivity and explosion power compared with un-expanded ANFO sample. The characterization techniques can be used to reveal the self-sensitization structure of EAN.
