单变量黄土结构势参数及其与增湿变形系数、振陷系数关系研究

发布时间：2018-03-28 21:22

本文选题：黄土　切入点：单变量结构势参数　出处：《西北农林科技大学》2014年博士论文

【摘要】：土的结构性是土物理状态的显示，是土生成条件、环境的自然历史产物。土的力学性质受其结构性的影响。黄土是一种典型的结构性土，具有独特的结构特性，容易发生“崩溃”性突变。这一现象不仅表现为黄土结构的“水敏性”，同时在动荷载作用下还表现出易损性。黄土在我国有着广泛的分布，工程病害及相关岩土工程问题在这一区域较为突出。因此，研究黄土的结构特性，考察黄土结构性与黄土湿陷、振陷等工程性质的关系，揭示其变化机理，对于指导黄土地区的工程实践具有重要的意义。本文在总结前人黄土结构性研究成果的基础之上，建立了单变量黄土结构势参数。通过侧限压缩试验、动扭剪试验研究了不同条件下黄土结构性及其结构势参数的变化规律，分别建立了黄土增湿变形系数、振陷系数与结构势参数的关系，拓展了结构性定量化参数的应用空间。本文成果如下： 1）总结了结构性研究成果，分析了黄土结构势参数的建立机制，建立了单变量黄土结构势参数。通过化简，静荷载条件下黄土结构变形势参数可用割线模量描述，进一步地可以获得以应力为变量的单变量黄土结构变形势参数；循环荷载条件下黄土结构动强度势参数可用动剪切模量描述，相应地获得了以动剪应变为变量的单变量黄土结构动强度势参数。 2）通过应变比拟，建立了黄土结构动变形势参数。进一步化简，获得以动剪应力为变量的单变量黄土结构动变形势参数。对黄土结构动强度势参数和结构动变形参数二者之间的关系进行了分析。 3）通过对杨凌、洛川两地黄土侧限压缩试验研究了静荷载条件下原状黄土结构变形势参数的变化规律，揭示了含水率和压力对黄土结构性的影响规律。分析了相同压力条件下含水率对黄土割线模量的影响规律，以此为基础建立了黄土结构变形参数与含水率之间的关系。 4）通过化简黄土增湿变形系数，获得以割线模量为参数的表达式。进一步与黄土结构变形势参数相联系，建立了黄土增湿变形系数与黄土结构变形势参数之间的关系，揭示了黄土结构势参数对黄土增湿变形系数的影响规律。分析了含水率、压力对二者关系的影响。 5）通过对杨凌黄土动扭剪试验研究循环荷载作用下原状黄土的结构动变形势参数和结构动强度势参数的变化规律。揭示围压、含水率、动剪应力、动剪应变对黄土结构性的影响规律。分析了相同动剪应变条件下，含水率对黄土动剪切模量的影响规律，建立了黄土结构动强度势参数与含水率之间的关系。 6）通过动扭剪试验研究了振次、含水率、围压、动剪应力等因素对黄土振陷特性的影响规律。建立了振陷系数与动剪应力之间的关系式，并使之与黄土结构动变形势参数相联系，，建立黄土振陷系数与黄土结构动变形势参数之间的关系式。揭示了黄土结构动变形势参数对黄土振陷系数的影响规律，分析了含水率、围压对二者关系的影响。
[Abstract]:The structural soil is a soil physical state that is soil formation conditions, natural history of product environment. Mechanical properties of soil under the influence of structural loess is a kind of typical structural soil, unique structure, prone to "collapse" mutation. This phenomenon not only showed the loess structure "water sensitivity", at the same time under dynamic loading also showed the vulnerability of loess in our country has a broad distribution of engineering disasters and related geotechnical engineering problem is more prominent in this area. Therefore, the structure characteristics of loess, loess structure investigation and collapsibility of loess, the relationship between vibration depression the engineering properties, the mechanism has important significance for the engineering practice in the loess area. Based on the former research achievements of structural loess, established a single variable structure of loess through the side pressure limiting potential parameters. Shrinkage test, variation of dynamic torsional potential parameters of loess and its structure under different conditions of shear test were established, the moistening deformation of loess seismic subsidence coefficient, relationship between the coefficient and the structure parameters of potential, expand the application space of structural quantitative parameters. The results are as follows:
1) summarizes the structural research results, establish the mechanism analysis of the structure of the potential parameters, a single variable loess structure potential parameters. Through simplification, describe the situation variable parameters available secant modulus of loess structure under static loading, the stress of the situation can be obtained by varying parameters of single variable loess structure variable cycle; the load condition of loess under dynamic structural potential parameter available dynamic shear modulus, obtained by dynamic shear strain dynamic strength potential parameters into a single variable loess structure variable.
2) through the strain analogy, we established the dynamic change situation parameters of loess structure. Further simplification, we obtained the single variable loess structural dynamic change situation parameters with dynamic shear stress as variables. We analyzed the relationship between the dynamic strength potential parameters of loess structure and the dynamic deformation parameters of the two.
3) in Yangling, Luochuan loess unconfined variation of loess structure change situation parameters under static loading compression test, reveals the water content and pressure on the influence law of loess structural. Analyze the influence of secant modulus of loess under the same pressure condition of water content, is established on the basis of the structure of the relationship between the deformation parameters and water content.
4) by simplifying the moistening deformation coefficient, secant modulus for expression to parameters. Further and loess structure situation parameter associated, established the moistening deformation of loess relations between parameters and variable coefficient of loess structure, reveals the influence law of loess structure potential parameters of moistening deformation coefficient on yellow soil. Analysis of the water content, the effect of pressure on the relationship between the two.
5) through the Yangling loess dynamic torsional shear test of loess structure under cyclic loading dynamic variation situation of strength potential parameters of dynamic parameters and structure change. To reveal the moisture content, confining pressure, shear stress, shear strain on the influence law of loess structure. The dynamic shear strain is analyzed in the same conditions. Effect of water content on the regulation of the loess dynamic shear modulus, establish the relationship between the strength of the potential parameters and water content of loess structure.
6) through the study of dynamic torsional vibration shear test, moisture content, confining pressure, the dynamic influence of shear stress and other factors on the vibration characteristics of depression was established. Dynamic subsidence coefficient and shear stress relation between stress, and loess structure change situation parameters linked to establish the vibration relation between dynamic parameters in variable situation coefficient and loess structure. The influences of dynamic change of loess structure parameters on the vibration situation in the analysis of the moisture content, the effect of confining pressure on the relationship between the two.

【学位授予单位】：西北农林科技大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU444

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