降雨条件下非饱和土流—固耦合试验与数值研究

发布时间：2018-06-14 11:27

本文选题：降雨 + 非饱和土　；参考：《成都理工大学》2013年硕士论文

【摘要】：非饱和土由多相介质组成，物理力学性质非常复杂，其理论至今不够完善和成熟。降雨诱发的非饱和土斜坡渗流、变形及稳定性问题是岩土工程界一直以来研究的重要课题，特别是雨水入渗与土体骨架变形耦合问题是近年来研究的热点。从流-固耦合的角度研究非饱和土体的渗流和变形，对理论研究和工程应用具有重要意义。以西南某地区松散堆积土为研究对象，通过压力板仪和非饱和土三轴仪开展试验研究，分析了非饱和土的土-水特征和变形特征，并采用有限元软件FlexPDE进行计算，研究了降雨入渗条件下非饱和土坡的渗流-变形耦合效应。具体研究内容和主要研究成果包括以下几点：（1）采用压力板仪进行了土体的脱水试验及一维固结试验，，获得了不同初始孔隙比、不同级配、不同应力状态下土-水特征曲线(Soil-Water CharacteristicCurve, SWCC)，不同应力状态下基质吸力-应变关系曲线，以及不同吸力状态下的应力-应变关系曲线，并且分析和探讨了土-水特征曲线及变形曲线变化规律。（2）采用GDS三轴仪进行非饱和土三轴压缩试验，获得了不同应力路径下的应力-应变关系曲线，并初步分析了非饱和粉质砂土在三维应力状态下的剪切变形规律。（3）根据达西定律、质量守恒定律及SWCC模型，逐步推导出了非饱和土渗流控制方程；引入有限元软件FlexPDE，编程求解非饱和土渗流控制方程，并分析和探讨非耦合情况下SWCC参数、降雨持时、降雨强度以及非饱和渗透系数的各向异性等对非饱和土斜坡渗流场分布的影响。（4）根据渗流理论、弹性理论及SWCC模型，建立非饱和土流-固耦合控制方程，将降雨过程作为边界条件，并赋以初始值，采用FlexPDE软件编程求解流-固耦合模型，并分析和探讨降雨持时、降雨强度、非饱和渗透系数的各向异性以及与基质吸力相关的土体体积模量等对非饱和土斜坡流-固耦合的影响。
[Abstract]:Unsaturated soil is composed of multiphase medium, and its physical and mechanical properties are very complex. The theory of unsaturated soil is not perfect and mature. The seepage, deformation and stability of unsaturated soil slope induced by rainfall have been an important research topic in geotechnical engineering field, especially the coupling of Rain Water infiltration and soil skeleton deformation is a hot topic in recent years. The study of seepage and deformation of unsaturated soil from the point of view of fluid-solid coupling is of great significance for theoretical research and engineering application. In this paper, the soil-water characteristics and deformation characteristics of unsaturated soils are analyzed by means of pressure plate and unsaturated soil triaxial analysis, and the finite element software FlexPDE is used to calculate them. The coupling effect of seepage and deformation on unsaturated soil slope under rainfall infiltration is studied. The concrete research contents and main research results are as follows: (1) the dewatering test and one-dimensional consolidation test of soil are carried out with pressure plate instrument, and different initial void ratios and different gradation are obtained. Soil-Water characteristic Curve, SWCCO, matrix suction strain relationship curves under different stress states, and stress-strain relationship curves under different suction states. The characteristic curves of soil-water and deformation curves are analyzed and discussed. (2) the stress-strain curves of unsaturated soils under different stress paths are obtained by using GDS triaxial test. The shear deformation of unsaturated silty sand under three dimensional stress is analyzed preliminarily. (3) according to Darcy's law, mass conservation law and SWCC model, the governing equation of unsaturated soil seepage is deduced step by step. The finite element software FlexPDE is introduced to solve the governing equation of unsaturated soil seepage, and the parameters of SWCC are analyzed and discussed under the condition of non-coupling. The influence of rainfall intensity and anisotropy of unsaturated permeability coefficient on the seepage field distribution of unsaturated soil slope. (4) based on seepage theory, elastic theory and SWCC model, the fluid-solid coupling governing equation of unsaturated soil is established. Taking the rainfall process as the boundary condition and assigning the initial value, the fluid-solid coupling model is solved by FlexPDE software, and the rainfall intensity when rainfall is sustained is analyzed and discussed. The effects of anisotropy of unsaturated permeability coefficient and bulk modulus of soil related to matrix suction on fluid-solid coupling of unsaturated soil slope.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU41

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