滇池泥炭土微观结构特征及工程力学模型研究
发布时间：2018-10-25 11:01
【摘要】：滇池泥炭土作为软粘土,其有机质含量较大、孔隙比(e)和含水量(ω)较大,力学性质较差。泥炭土上修建的建筑物容易产生不均匀沉降,因此对泥炭土物理力学性质统计分析,微观结构特征的分析以及本构模型的研究有很重要的理论价值和实用价值。本文通过收集昆明地铁1、2线中滇池泥炭土的勘察数据,并对其进行统计分析。结合滇池泥炭土的电镜扫描和组分分析实验,对泥炭土微观结构进行定性和定量的分析。通过单轴固结试验和常规三轴试验对泥炭土力学性质进行分析,并结合以上分析提出符合滇池泥炭土的改进邓肯-张模型。本文主要的研究成果如下：(1)收集昆明地铁1、2号线滇池泥炭土原状土样的物理力学指标数据,对数据进行统计和分析,列出滇池北部滇池泥炭土个物理力指标的变化范围,对该区域工程建设有一定的指导作用。其次对其个物理力学各指标间的相互关系进行研究,结果表明天然含水率与孔隙比、重度与孔隙比的相关较好,通过经验公式可以获得滇池泥炭土的孔隙比；有机质含量与物理力学中各参数指标关系度较小；通过统计的直剪试验和固结快剪试验的参数指标,发现其指标之间的数据较离散,相关性较小。(2)通过能谱分析和微观电子扫描电镜试验,表明滇池泥炭土的粘土矿物主要为伊利石、绿泥石,含有部分高岭石；多组的SEM图片的分析及前人研究将泥炭土的结构特性主要分为三类：蜂窝状结构,骨架装结构,絮凝状结构；通过ImageJ软件对SEM图像处理,得出泥炭土的微观结构的定量参数。(3)通过单轴固结试验和常规三轴试验,表明滇池泥炭土具有一定的结构性,其原状土跟重塑土的压缩性有一定的区别,并对其进行了微观行为的解释。滇池泥炭土的应力应变关系曲线可以分为三个阶段：第一阶段土体结构较完整,其土体的变形中弹性变形为主要的；第二阶段结构破坏,其土体的塑性变形量比弹性变形量多；第三阶段结构完全破坏,此时段土的性质跟重塑土相似。(4)介绍邓肯-张模型的基本理论及所需参数的求解公式,同时引入了损伤比概念。使邓肯-张模型具有三个不同的初始弹性模量,即土体完整阶段的初始弹性模量,结构破损阶段的初始弹性模量,结构完全破损阶段的初始弹性模量。同时对模型进行对比,表明修改后的模型较好的体现泥炭土的性质。
[Abstract]:As soft clay in Dianchi Lake, the organic matter content, porosity ratio (e) and water content (蠅) of the peat soil in Dianchi Lake are large, and the mechanical properties are poor. The buildings built on the peat soil are prone to uneven settlement, so the statistical analysis of the physical and mechanical properties of the peat, the analysis of the microstructure characteristics and the study of the constitutive model are of great theoretical and practical value. In this paper, the survey data of the peat soil in Dianchi Lake in Kunming Metro Line 1 / 2 are collected and analyzed statistically. The microstructure of peat soil in Dianchi Lake was analyzed qualitatively and quantitatively by SEM and component analysis experiments. The mechanical properties of peat were analyzed by uniaxial consolidation test and conventional triaxial test, and an improved Duncan-Zhang model was put forward in accordance with the above analysis. The main research results of this paper are as follows: (1) collecting the physical and mechanical index data of the peat soil samples of Dianchi Lake in Kunming Metro Line 1 and 2, making statistics and analysis of the data, and listing the variation range of the physical force index of the peat soil in the northern Dianchi Lake. It has certain guiding function to the project construction in this area. Secondly, the relationship between physical and mechanical indexes is studied. The results show that the correlation between natural water content and porosity ratio, heavy degree and porosity ratio is better, and the porosity ratio of peat soil in Dianchi Lake can be obtained by empirical formula. The relationship between the content of organic matter and the parameters of physical mechanics is relatively small, and through the statistical direct shear test and consolidation fast shear test, it is found that the data between the two indexes are more discrete. (2) the clay minerals of the peat soil in Dianchi Lake are mainly Illite, chlorite and some kaolinite by energy dispersive analysis and SEM test. The structural characteristics of peat are divided into three types: honeycomb structure, skeleton structure, flocculation structure, SEM image processing by ImageJ software. The quantitative parameters of the microstructure of peat soil are obtained. (3) through uniaxial consolidation test and conventional triaxial test, it is shown that the peat soil in Dianchi Lake has a certain structure, and the compressibility of the undisturbed soil is different from that of the remolded soil. The microcosmic behavior is explained. The stress-strain relationship curve of peat soil in Dianchi Lake can be divided into three stages: in the first stage, the soil structure is relatively complete, the elastic deformation is the main part of the soil deformation, the second stage is the structure failure, the plastic deformation of the soil is more than that of the elastic deformation. In the third stage, the properties of the soil are similar to those of the remolded soil. (4) the basic theory of Duncan-Zhang model and the formula of the required parameters are introduced, and the concept of damage ratio is introduced. The Duncan-Chang model has three different initial elastic moduli, that is, the initial elastic modulus in the complete stage of soil, the initial elastic modulus in the stage of structural damage, and the initial elastic modulus in the stage of complete damage of the structure. At the same time, the comparison of the model shows that the modified model well reflects the properties of peat.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU447;TU411
本文编号：2293518
[Abstract]:As soft clay in Dianchi Lake, the organic matter content, porosity ratio (e) and water content (蠅) of the peat soil in Dianchi Lake are large, and the mechanical properties are poor. The buildings built on the peat soil are prone to uneven settlement, so the statistical analysis of the physical and mechanical properties of the peat, the analysis of the microstructure characteristics and the study of the constitutive model are of great theoretical and practical value. In this paper, the survey data of the peat soil in Dianchi Lake in Kunming Metro Line 1 / 2 are collected and analyzed statistically. The microstructure of peat soil in Dianchi Lake was analyzed qualitatively and quantitatively by SEM and component analysis experiments. The mechanical properties of peat were analyzed by uniaxial consolidation test and conventional triaxial test, and an improved Duncan-Zhang model was put forward in accordance with the above analysis. The main research results of this paper are as follows: (1) collecting the physical and mechanical index data of the peat soil samples of Dianchi Lake in Kunming Metro Line 1 and 2, making statistics and analysis of the data, and listing the variation range of the physical force index of the peat soil in the northern Dianchi Lake. It has certain guiding function to the project construction in this area. Secondly, the relationship between physical and mechanical indexes is studied. The results show that the correlation between natural water content and porosity ratio, heavy degree and porosity ratio is better, and the porosity ratio of peat soil in Dianchi Lake can be obtained by empirical formula. The relationship between the content of organic matter and the parameters of physical mechanics is relatively small, and through the statistical direct shear test and consolidation fast shear test, it is found that the data between the two indexes are more discrete. (2) the clay minerals of the peat soil in Dianchi Lake are mainly Illite, chlorite and some kaolinite by energy dispersive analysis and SEM test. The structural characteristics of peat are divided into three types: honeycomb structure, skeleton structure, flocculation structure, SEM image processing by ImageJ software. The quantitative parameters of the microstructure of peat soil are obtained. (3) through uniaxial consolidation test and conventional triaxial test, it is shown that the peat soil in Dianchi Lake has a certain structure, and the compressibility of the undisturbed soil is different from that of the remolded soil. The microcosmic behavior is explained. The stress-strain relationship curve of peat soil in Dianchi Lake can be divided into three stages: in the first stage, the soil structure is relatively complete, the elastic deformation is the main part of the soil deformation, the second stage is the structure failure, the plastic deformation of the soil is more than that of the elastic deformation. In the third stage, the properties of the soil are similar to those of the remolded soil. (4) the basic theory of Duncan-Zhang model and the formula of the required parameters are introduced, and the concept of damage ratio is introduced. The Duncan-Chang model has three different initial elastic moduli, that is, the initial elastic modulus in the complete stage of soil, the initial elastic modulus in the stage of structural damage, and the initial elastic modulus in the stage of complete damage of the structure. At the same time, the comparison of the model shows that the modified model well reflects the properties of peat.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU447;TU411
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