邢衡高速路基软土的微结构本构模型

发布时间：2018-01-04 16:11

本文关键词：邢衡高速路基软土的微结构本构模型　出处：《河北工业大学》2015年硕士论文　论文类型：学位论文

更多相关文章：软土 微结构 PFC 弹塑性 本构模型

【摘要】：近年来国内经济建设越来越发达,各种各样的建筑层出不穷,且大部分建筑物位于滨海相或湖泊相分布较广的软土地区,由软土带来的地质灾害等现象越来越受到关注。而软土具有微观结构性,所以使用目前已经发展成熟的模型来估算软土的变形量时,那些模型得出的估算结果与实测数值相比并不一致,因此在针对软土特性的分析中,考虑微观特征的软土本构模型成为当下备受关注的课题。本文中依托邢衡高速软土,对软土的微结构本构模型进行了分析。本文展开的工作包括以下内容和结论:1、通过对邢衡高速路基软土原状土进行室内土工试验和电镜扫描试验,得出基本物理力学性质和SEM图像。进而得出邢衡高速路基软土原状土的孔隙孔径分布、孔隙微结构定量参数、颗粒微结构定量参数,并且针对不同应力状态下的试样垂直面和水平面的SEM图片即微观电镜扫描照片作出了定量分析及比对,揭示了土体变形过程中土体颗粒和孔隙的变化规律,从而在微观上阐述土体发生宏观变形的规律。2、运用颗粒流程序PFC对标准固结试验和常规三轴试验进行了仿真模拟,得出了应力应变曲线,通过将数值模拟结果与实测试验结果对比发现PFC内置接触本构模型都能够在一定程度上反映出实际土样的本构关系。3、基于目前工程中常用的本构模型建立了软土的微结构本构模型。假设软土颗粒接触面上的屈服准则服从以摩尔库伦准则为基础的弹塑性准则。弹性部分通过赫兹麦德林准则求出,塑性部分通过引入一个锥状屈服面反映其特性。通过“优化假设方法”实现微观颗粒接触面上的位移到宏观应变的转化,然后通过能量守恒的方法实现微观接触面上的力到宏观应力的转化。然后运用标准固结试验和常规三轴试验数据对本构模型进行了验证,所得的模型可以在微观层面描述出土体的宏观的本构关系,模型计算得出的结果与试验实测数据相比对表明一致性。
[Abstract]:In recent years, the domestic economy developed more and more, all kinds of buildings in soft soil area and emerge in an endless stream, most of the buildings in coastal or lake facies is widely distributed, and brought by soft soil geological disasters such as the phenomenon of more attention. The soft soil with micro structure, so the use of the current mature model to estimate the deformation the amount of soft soil, the estimation results derived from the model and the measured value is compared is not consistent, so the analysis for soft soil characteristics, constitutive model has become the topic of concern in soft soil microstructure characteristics are considered. This paper based on the high speed soft soil micro structure of Xing Heng, soft soil constitutive model the analysis. The main work includes the following contents and conclusions: 1, through indoor soil test and SEM test of high-speed Xing Heng Subgrade in soft soil undisturbed soil, obtained the basic physical and Mechanical The nature and SEM image. Then we can get the pore size distribution of high speed Xing Heng soft roadbed soil, pore micro structure quantitative parameters, particle microstructure quantitative parameters, and according to the different stress state of specimen of vertical surface and horizontal surface SEM picture: micro scanning electron microscope photos made quantitative analysis and comparison, reveals the change the deformation of soil particles and pores of soil, so the soil macro deformation regularity of.2 in the micro level, using particle flow code PFC on the standard consolidation test and the conventional three axis test simulation, the stress-strain curve, the numerical simulation results and the actual test results found in PFC contact constitutive model can reflect the actual.3 constitutive relation of soil to a certain extent, based on the commonly used constitutive model of micro structure of soft soil constitutive model in Engineering Type. Assuming yield criterion of soft soil particles on the surface of the contact to obey Moore in Kulun criterion based elastic-plastic elastic criterion. Part of the Medellin criteria for Hertz, plastic parts introduce a cone yield surface reflects its characteristics. Through the optimization of "transformation assumption method" to achieve the displacement of microscopic particles on contact surface. To the macroscopic strain, and then into the macro stress by the method of energy conservation to achieve micro contact surface force. Then using the verification of the constitutive model for standard consolidation test and conventional three axis test data, the model can describe the soil macro constitutive relation at the micro level, the calculation results of the model the results show that compared with the experimental data for consistency.

【学位授予单位】：河北工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U416.1

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