Abstract
Loess is a kind of typical structural soil, which is widely distributed in China. And a large number of engineering activities are carried out in loess area. On the other hand, due to the special nature of loess, the geological environment conditions such as hydrology and climate in loess area and the influence of human engineering activities, the disaster in loess area is extremely developed. So it is particularly important that how to correct understand the structural mechanics properties of loess, and how to find a constitutive model which can accurately describe the mechanical behavior of structural loess. Through this, we can accurately describe and predict the mechanical behavior of structural loess. In this paper, we use natural structural loess as the research object, through basic test to get the basic physical and mechanical parameters of structural loess, On the basis of the concept of superloading Cam-Clay model, in view of structural loess, We improved the evolution of structural state change parameters and a modified constitutive model is proposed. Fortran programming was adopted to verify the model by comparing with the one-dimensional consolidation test and the three-axis consolidated drainage shear test data. The work carried out mainly includes the following aspects:
(1)The basic properties of L5 loess were determined by geotechnical experiments. The static side pressure experiment, one-dimensional consolidation experiment and three axial consolidation test were carried out for L5 original and remolding samples respectively. Comparative study on the structure of loess.
(2)According to the structural loess, on the basis of the superloading Cam-Clay model, we analyzed the overconsolidation and structure of loess from the e-ln p curve. We improved the evolution of structural state change parameters by using the concept of void ratio. So we can make the model can better describe the natural loess in different before and after the yield stress strain relationship, make the concept of the parameters is more clear, a constitutive equation of structural loess is proposed.
(3)The parameters of L5 model were determined by experiment and simple test.
(4)Through basic test to get parameters of model, and comparing the data of one-dimensional consolidation experiment with the data of triaxial consolidated-drained shear experiment by Fortran program, we are sure that our model can effectively depict stress-strain relationship of structural loess.
Key words: loess, structural, constitutive model, numerical simulation
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目录
第一章引言 (1)
1.1 选题背景及意义 (1)
1.2 国内外研究现状 (1)
1.2.1 黄土物理力学性质研究现状 (1)
1.2.2 黄土结构性研究现状 (2)
1.2.3 黄土本构模型研究现状 (3)
1.3 本文的主要工作内容 (4)
1.3.1 研究内容 (4)
1.3.2 技术路线 (5)
第二章结构性黄土试验研究 (6)
2.1 取样地点和方法 (6)
2.2 基本物理性质试验 (7)
2.3 试样制备 (10)
2.3.1 原状试样制样方法 (10)
2.3.2 重塑试样制样方法 (10)
2.4 静止侧压力系数实验 (14)
2.4.1 试验方法及步骤 (14)
2.4.2 试验数据处理 (14)
2.5 固结实验 (15)
2.5.1 试验方法及步骤 (15)
2.5.2 试验数据处理 (16)
2.6 等向压缩固结试验 (22)
2.6.1 试验方法及步骤 (23)
2.6.2 试验数据处理 (25)
2.7 常规三轴试验 (27)
2.7.1 试验方法及步骤 (27)
2.7.2 试验数据处理 (28)
第三章黄土结构性本构模型 (30)
3.1 基本模型 (30)
3.2 模型屈服方程 (31)
3.3 状态变量演化式构造 (35)
3.3.1 超固结状态变量演化式构造 (35)
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3.3.2 结构性状态变量演化式构造 (36)
3.4 流动法则和加载准则 (37)
3.5 弹塑性刚度矩阵推导 (38)
第四章黄土结构性本构模型程序的实现 (42)
4.1 程序的编制 (42)
4.2 模型参数确定及分析 (43)
4.2.1 模型参数的确定 (43)
4.2.2 模型参数分析 (45)
4.3 模型计算结果检验 (47)
4.3.1 参数合适性检验 (47)
4.3.2 一维固结实验对比 (49)
4.3.3 三轴实验数据对比 (50)
结论与展望 (53)
参考文献 (55)
攻读学位期间取得的研究成果 (60)
致谢 (61)
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