In this paper,macro-and micro-properties of natural marine clay in two different and representative regions of China are investigated in detail.In addition to in-situ tests,soil samples are collected by use of Shelby ...In this paper,macro-and micro-properties of natural marine clay in two different and representative regions of China are investigated in detail.In addition to in-situ tests,soil samples are collected by use of Shelby tubes for laboratory examination in Shanghai and Zhuhai respectively,two coastal cities in China.In the laboratory tests,macro-properties such as consolidation characteristics and undrained shear strength are measured.Moreover,X-ray diffraction test,scanning electron microscope test,and mercury intrusion test are carried out for the investigation of their micro-properties including clay minerals and microstructure.The study shows that：（1）both clays are Holocene series formations,classified as either normal or underconsolidated soils.The initial gradient of the stress-strain curves shows their increase with increasing consolidation pressure;however,the Shanghai and the Zhuhai clays are both structural soils with the latter shown to be more structured than the former.As a result,the Zhuhai clay shows strain softening behavior at low confining pressures,but strain hardening at high pressures.In contrast,the Shanghai clay mainly manifests strain-hardening.（2）An activity ranges from 0.75 to 1.30 for the Shanghai marine clay and from 0.5 to 0.85 for the Zhuhai marine clay.The main clay mineral is illite in the Shanghai clay and kaolinite in the Zhuhai clay.The Zhuhai clay is mainly characterized by a flocculated structure,while the typical Shanghai clay shows a dispersed structure.The porous structure of the Shanghai clay is characterized mainly by large and medium-sized pores,while the Zhuhai clay porous structure is mainly featured by small and medium-sized pores.The differences in their macro-and micro-properties can be attributed to different sedimentation environments.展开更多
针对土壤中全硼测定存在难消解、干扰大、易挥发损失等问题,利用碱熔法、微波消解法以及微敞开石墨消解法对土壤全硼进行了测定分析,优化了消解条件,并对三种消解方式进行了验证对比。结果表明:碱熔剂种类以及用量会对碱熔法的准确性造...针对土壤中全硼测定存在难消解、干扰大、易挥发损失等问题,利用碱熔法、微波消解法以及微敞开石墨消解法对土壤全硼进行了测定分析,优化了消解条件,并对三种消解方式进行了验证对比。结果表明:碱熔剂种类以及用量会对碱熔法的准确性造成较大影响,选择KOH作为碱熔剂,并且KOH添加量为3.0 g时,可以获得更准确的结果;加酸种类以及赶酸温度的选择对微波消解法测定结果影响较大,选择加酸体系(5 mL HNO_(3)+1 mL HCl+3 mL HF+1.5 mL H_(3)PO_(4)),赶酸时温度选择170℃,测试效果较好;不同的加酸体系以及消解温度同样会引起微敞开石墨消解法测定结果出现较大误差,选择加酸体系(5 mL HNO_(3)+1 mL HClO_(4)+3 mL HF+1.5 mL H_(3)PO_(4)),消解温度设为170℃,测定结果更可靠。方法验证对比结果表明,碱熔法检出限为0.7 mg/kg,微波消解法检出限为0.9 mg/kg,微敞开石墨消解法检出限为1.0 mg/kg,均满足分析测定的要求。三种消解方式测定的准确度和精密度均符合要求,均可用于土壤全硼的测定,并且实际样品测定结果无显著性差异。三种消解方式优缺点和适用范围不同,实际测试时可以根据样品数量及样品中全硼大致含量等选择具体的消解方式。建立的方法可以为第三次全国土壤普查内业检测提供参考和借鉴。展开更多
微政务作为迅速发展的跨学科研究领域,已经初步形成了完整的知识体系。本文选取2010-2016年间WOS(Web of Science数据库)、CNKI(中国知网)以微政务为关键词的期刊论文,以文献计量学为基础理论和方法,以Cite SpaceⅢ为数据分析和可视化工...微政务作为迅速发展的跨学科研究领域,已经初步形成了完整的知识体系。本文选取2010-2016年间WOS(Web of Science数据库)、CNKI(中国知网)以微政务为关键词的期刊论文,以文献计量学为基础理论和方法,以Cite SpaceⅢ为数据分析和可视化工具,通过高频关键词的时区图和网络图、学科分布图、期刊分布图等,对比分析了国内外微政务研究所处的研究阶段与发展脉络、研究流派与主体、研究主题与方法,并提出了未来的研究趋势。展开更多
基金supported bythe National Natural Science Foundation of China(Grant No.50679057)the National High Technology Research and Development Program of China(863 Program,Grnat No.2006AA11Z102)+1 种基金the Shanghai Pujiang Program(Grant No.06PJ14088)the Zhuhai city Science Technology Program(Grant No.PA200310064)
文摘In this paper,macro-and micro-properties of natural marine clay in two different and representative regions of China are investigated in detail.In addition to in-situ tests,soil samples are collected by use of Shelby tubes for laboratory examination in Shanghai and Zhuhai respectively,two coastal cities in China.In the laboratory tests,macro-properties such as consolidation characteristics and undrained shear strength are measured.Moreover,X-ray diffraction test,scanning electron microscope test,and mercury intrusion test are carried out for the investigation of their micro-properties including clay minerals and microstructure.The study shows that：（1）both clays are Holocene series formations,classified as either normal or underconsolidated soils.The initial gradient of the stress-strain curves shows their increase with increasing consolidation pressure;however,the Shanghai and the Zhuhai clays are both structural soils with the latter shown to be more structured than the former.As a result,the Zhuhai clay shows strain softening behavior at low confining pressures,but strain hardening at high pressures.In contrast,the Shanghai clay mainly manifests strain-hardening.（2）An activity ranges from 0.75 to 1.30 for the Shanghai marine clay and from 0.5 to 0.85 for the Zhuhai marine clay.The main clay mineral is illite in the Shanghai clay and kaolinite in the Zhuhai clay.The Zhuhai clay is mainly characterized by a flocculated structure,while the typical Shanghai clay shows a dispersed structure.The porous structure of the Shanghai clay is characterized mainly by large and medium-sized pores,while the Zhuhai clay porous structure is mainly featured by small and medium-sized pores.The differences in their macro-and micro-properties can be attributed to different sedimentation environments.
文摘针对土壤中全硼测定存在难消解、干扰大、易挥发损失等问题,利用碱熔法、微波消解法以及微敞开石墨消解法对土壤全硼进行了测定分析,优化了消解条件,并对三种消解方式进行了验证对比。结果表明:碱熔剂种类以及用量会对碱熔法的准确性造成较大影响,选择KOH作为碱熔剂,并且KOH添加量为3.0 g时,可以获得更准确的结果;加酸种类以及赶酸温度的选择对微波消解法测定结果影响较大,选择加酸体系(5 mL HNO_(3)+1 mL HCl+3 mL HF+1.5 mL H_(3)PO_(4)),赶酸时温度选择170℃,测试效果较好;不同的加酸体系以及消解温度同样会引起微敞开石墨消解法测定结果出现较大误差,选择加酸体系(5 mL HNO_(3)+1 mL HClO_(4)+3 mL HF+1.5 mL H_(3)PO_(4)),消解温度设为170℃,测定结果更可靠。方法验证对比结果表明,碱熔法检出限为0.7 mg/kg,微波消解法检出限为0.9 mg/kg,微敞开石墨消解法检出限为1.0 mg/kg,均满足分析测定的要求。三种消解方式测定的准确度和精密度均符合要求,均可用于土壤全硼的测定,并且实际样品测定结果无显著性差异。三种消解方式优缺点和适用范围不同,实际测试时可以根据样品数量及样品中全硼大致含量等选择具体的消解方式。建立的方法可以为第三次全国土壤普查内业检测提供参考和借鉴。
文摘微政务作为迅速发展的跨学科研究领域,已经初步形成了完整的知识体系。本文选取2010-2016年间WOS(Web of Science数据库)、CNKI(中国知网)以微政务为关键词的期刊论文,以文献计量学为基础理论和方法,以Cite SpaceⅢ为数据分析和可视化工具,通过高频关键词的时区图和网络图、学科分布图、期刊分布图等,对比分析了国内外微政务研究所处的研究阶段与发展脉络、研究流派与主体、研究主题与方法,并提出了未来的研究趋势。
