【作者】 刘功勋；

【导师】 张向东；

【作者基本信息】 辽宁工程技术大学 ， 岩土工程， 2007， 硕士

【摘要】 通过一系列室内常规土工试验,包括密度、含水率、比重、颗粒分析以及固结和剪切等试验,得到风积土各种基本物理、力学指标,为后面的试验及理论分析创造条件。研究原状风积土颗粒的排列和联结特征以及重塑土和饱和土的宏观力学性质,结合电子显微镜观察,将辽西地区风积土与其他地区土体进行对比分析,揭示了风积土独有的结构性:由计算得到的压缩系数说明原状土的压缩性最小,饱和土压缩性最大。这主要因为原状土未受到扰动,土颗粒的排列和联结并未受到破坏,而重塑土和饱和土的原始结构已经受到破坏,所以其压缩性比原状土要大,这是风积土具有明显结构性的宏观反映。e-lgt曲线的线型有较大区别:随着压力的增大,主、次固结的划分由不明显变为明显,之后又变为不明显,这与饱和软粘土明显不同。以综合结构势作为结构性参数,将阜新地区风积土与兰州和潍坊地区土体进行了对比分析,发现有显著差异。此外,通过电子显微镜观察得到的图片与其他地区土体细观结构图片进行对比,反映出其结构致密、强度较高的特性。利用改进的冻融试验装置对辽西地区典型风积土样进行了冻融试验。试验结果表明:随着温度梯度的增大,最大冻胀量和融沉值有不同程度的减小;无论在封闭系统还是在开敞系统中,外力的存在都对冻胀起到抑制作用,融沉值也会随着荷载的增大而减小;外界水分的补给会使最终冻胀量和融沉值都显著增加。试样冻融后,孔隙特征发生了明显的变化,孔隙特征的变化必然导致土骨架特征发生相应的变化,使传力骨架的结构体系发生位移,造成结构性的变化。试样冻融后,抗剪强度的粘聚力部分有所降低,抗剪强度的摩擦力部分有所增大,即内摩擦角有所增大。这与孔隙变化所引起土颗粒间接触点增大和排列不规则性增大的结果是一致的。以冰率作为结构性参数,通过研究其在冻融过程中随水分场和应力场的变化来揭示风积土冻融过程结构性演变规律。更多还原

【Abstract】 All kinds of basic physical and mechanical indexes are gained by doing a series of indoor conventional soil mechanics tests ,including density,water ratio,specific density,particle-size analysis ,consolidation and shearing tests.This creates condition for the following experimentation and theory analysis.By studing the arrangement and connection character of the undisturbed soil particle and the macroscopical mechanical property of the disturbed soil and the saturated soil,using the electronic microscope to observe the soil samples,comparing the aeolian soil in the west of Liaoning area to other areas,the unique structure characteristic of the aeolian soil is opened out. The compression coefficient indicates that the displacement of the undisturbed soil sample is the smallest ,the disturbed soil is next and the saturated soil sample is the biggest under the same pressure .This is mainly because the undisturbed soil is not disturbed so that the arrangement and connection are not damaged,yet the original structures of the disturbed soil and the saturated soil are damaged and it is the macroscopic reflect of having obvious structure character. The shape of the e-lgt curve are different obviously:with the increase of the pressure ,the division of the primary consolidation and the secondary consolidation becomes obviouser firstly and then becomes not obviouser.It is different greatly with the saturated soft clay . Using synthesized structure potential as structure parameter to compare the aeolian soil in Fuxin with the soil in Lanchow and Weifang,the result shows that they have marked difference.Moreover,the difference between the pictures which are gained by observing under electronic microscope and the microstructure pictures in other areas reflects the characteristics of dense structure and high strength.The typical aeolian soil samples in the western area of Liaoning province are frozen and thawed by using the improved freezing-thawing device. The test results indicate that the maximal swelling magnitude and thaw collapse value decreased with the increase of the temperature gradient;Not only in the closed system but also in the open system,the external force suppressed the swelling,the thaw collapse value also decreased with the increase of the load;The external water supply will increase markedly the ultimate swelling magnitude and thaw collapse value.After freezing and thawing,the pore feature of the soil changed obviously.This change inevitably leads to the variation of the frame feature correspondingly and makes the structural system of delivering power frame creates internal displacement so that the structure was changed. After freezing-thawing,the cohesive strength part of the shear strength decreased and the friction force part increased,that is internal friction angle increased. This is consistent with the result of the increase of contact point between the soil particles and the irregularity of arranging which is caused by the pore change.The ice efficiency is used as structure parameter and the structure evolvement regularity of aeolian soil is illustrates by studing the change with the water field and the stress field during the perild of freezing and thawing.更多还原