太湖第四纪沉积区土体荷载响应的效应综合特征

土的微结构对土的力学行为机制起着至关重要的作用,对太湖第四纪沉积区典型软土进行单向压缩试验,利用扫描电子显微镜(SEM)所得的照片研究软土在不同固结压力条件下的微结构大小、形状、定向性等微结构参数,分析其变化规律.研究表明,随着固结压力的增加,结构单元体不断变大,集合体的形状在垂直于压力的方向变长,结构单元体的定向性有所提高但不显著；孔隙分布分维呈下降趋势并逐步稳定.采用电镜扫描仪(SEM)对在复杂应力路径作用下剪切前后的黏土样进行微观观察,并从剪切前后孔隙排列、孔隙形态、孔隙尺度变化特征3个方面分析宏观试验原状软黏土归一化抗剪强度各向异性的微观本质.阐述了淤泥类软土的微观结构对其工程性质的重要影响.从泥炭的微观结构分析入手研究了泥炭的性质及特点(包括含水性质、强度性质、固结及次固结性质).讨论了海积软土在固结、剪切作用下微观结构的变化,阐述了海积软土力学行为的本质.通过室内一维固结蠕变试验系统研究分析了次固结系数与固结压力、时间及压缩指数的关,揭示了太湖第四纪沉积区软土的次固结特性.利用扫描电镜试验( SEM)和X射线能谱仪对软黏土中常见的微量元素进行测定,计算其相对百分比并分析了该土的矿物成分和微观结构组成.实验结果表明,该黏土主要以高岭石、埃洛石(伊利石)、水云母(蒙脱石)为主(其中硅为其主要成分,局部的矿物组成有稍许不同).

Research on Comprehensive Features for Load Response Effect of Soil of Quaternary Deposition Area in Taihu Basin

Structural properties of soil had a great impact on mechanical properties of the soil.Uniaxial compression test was completed for soft soil of quaternary deposition area in Taihu Basin.The use of scanning electron microscope(SEM) photos of soft soil in different pressure,to study the different micro-structural parameters including the size,shape,orientation of pores and structural units,to analyze the changes in the rules.Studies show that: with the increasing consolidational pressure,the structural units are biger constantly and the shape of aggregates in the perpendicular direction to the pressure is longer,the orientation of structural units is increased,but not significantly.Distribution dimensions of pores decline with the increasing consolidation pressure and trend to become stable.SEM was used to observe microstructure of soft clay before and after shearing under complex stress path,which analyzed microscopic nature on anisotropy of normalized shear strength of intact soft clay in three respects including changing characteristics of pore arrangement,changing characteristics of pore pattern and changing characteristics of pore scale.Important influence of microstructure of mud on its engineering properties has been discussed.Through analysis for the microstructure of the peat,properties and characteristics of peat were studied,which include water content,strength,consolidation and secondary consolidation properties.The changes of microstructure of marine soft soil under consolidation and shear are discussed,the soft soil mechanical behavior is analyzed.In order to study on characteristics of soft clay in quaternary deposition area in Taihu Basin systematically,relationships between coefficient of secondary consolidation and consolidation pressure,time and compression index are analyzed by 1-D consolidation creep test.The composition of mineral composition and microstructure of the clay in quaternary deposition area in Taihu Basin were determined by using scanning electron microscopy and X-ray spectrometer,and their relative percentages were calculated.It was found that the clay mainly contained Kaolinite,ella los stone(illite),water mica(montmorillonite),and silicon as the main ingredient.