【作者】 肖夺；

【导师】 杨和平；

【作者基本信息】 长沙理工大学 ， 道路与铁道工程， 2006， 硕士

【摘要】 膨胀土是一种因环境干湿交替作用而发生体积明显膨胀(收缩)、强度剧烈衰减而导致工程变形破坏且含有较多膨胀性粘土矿物的非饱和土。膨胀土对工程建设的危害,尤其路堑边坡的滑坍是膨胀土地区公路建设中普遍存在且亟待解决的技术难题。除了土性因素、干湿循环作用外,降雨入渗后土体膨胀、强度衰减是边坡滑坍的主要原因。因此,研究膨胀土体的渗透特性,分析降雨与边坡稳定性的关系具有非常重要的意义。然而要研究非饱和膨胀土的渗透特性绝非易事,目前成熟的膨胀土渗透特性的试验方法还不存在。为此,本文尝试以宁明膨胀土为对象,开展其渗透特性的初步试验研究。首先,从成因类型、分布特征以及微观结构方面研究了宁明膨胀土的特性。在此基础上,以非饱和土理论为指导,进行室内渗透试验设计并对试验结果和试验中发生的现象进行合理的分析和解释。借助先进的GDS非饱和三轴系统,开展了非饱和膨胀土含水量与渗透特性的试验研究,由测得的土水特征曲线间接获得渗透系数,并选用VG模型对试验结果的真实可靠性加以验证。结果表明,宁明膨胀土的含水量与渗透系数之间呈非线性关系,可用对数函数来加以拟合,由此提出宁明非饱和膨胀土渗透系数与含水量的理论公式。试验过程中还对GDS系统的陶土板底座渗透系数进行了标定。考虑到土体结构性对其渗透特性的影响,采用常规实验方法,进行了较系统的室内饱和土渗透试验,获得土体孔隙性、扰动性、结构构成对宁明膨胀土渗透特性的影响,总结出渗透系数随孔隙比、土体深度、渗流方向等的变化规律,并进行了量化描述,得出膨胀土渗透系数与孔隙比的函数关系式。全文抓住孔隙比、含水量和土体结构性三个影响非饱和膨胀土渗透特性的主要因素来开展室内渗透试验研究,目的是探讨宁明膨胀土的渗透特性及变化规律,为广西南友路膨胀土堑坡稳定性分析提供合理的渗流参数。更多还原

【Abstract】 Expansive soil is a kind of unsaturated soils which contain lots of swelling clay minerals, and usually make structures deformate and destroyed with its strength decease sharply as swelling and shrinkage due to the change of its water content in the fluency of weather. The slide of slope is the biggest technique problem during the construction of road in the regions of expensive soils. In addition to the character of expansive soil and the effect of wet-dry cycling, the expanding of soils with the seepage of the rainfalls and the attenuation of shear strength are the main reasons of slide of expansive soils slope. So it is all-important to research the permeability of soil and analyze the stability of rainfalls with slide of expansive soils slope. Nowadays the feasible tests method of permeability is inexistence, the studying of permeability of unsaturated expansive soil is still have lots of difficulties need to be solved. Therefore this thesis primary carried out the tests on characteristic of penetrability of Ningming unsaturated expansive soils.First the thesis studied the characteristic of Ningming expansive soils from its type of origins, distributing as well as its microstructure, analyzed the results of permeability tests and the phenomena in the tests with the guidance of theory of unsaturated soils. Using advanced GDS unsaturated Triaxial testing system, the thesis studied the relationship of water-content and permeability, the coefficient of permeability result that is worked out indirectly by Soil-water characteristic curve tests indicates non-linear relationship of water-content and coefficient of permeability of Ningming unsaturated expansive soils, and the facticity of tests result has been validated by combining with the outcome of the VG imitate model. Therefore the theoretic formula of Ningming unsaturated expansive soils that is the relationship with water-content and coefficient of permeability is put forward. In this tests, the coefficient of permeability of the high air entry disk base of GDS unsaturated Triaxial testing system is also demarcated.Considering the influence of structure on permeability of Ningming expansive soils, the thesis designed and done general permeability test elaborately, studied and summarized the influence of void、disturbance and structure with the permeability of Ningming expansive soils. Variability of the coefficient of permeability has been acquired with the changing of void ratio、earth depth and seepage direction, its influence function formula is also put forward.The whole thesis focused on three main factors of void ratio, water-content and structure of earth which influence on the permeability of unsaturated expansive soils to study the permeability by test, the aim is acquire permeability and its variability of更多还原