膨胀土裂隙演化三维分布特征及渗流特性研究

Engineering disasters induced by swell-shrink and crack characteristics of expansive soil have repeatability and long-term, crisscross fissures produced by repeatedly swell-shrink in the soil, provide a good channel for rainfall infiltration and evaporation. The characteristics of seepage problem are obviously different between expansive soil and general unsaturated soil. The research use the slope stability and protection project of expansive soil as the background, use the expansion soil of typical area as the research object, use macro-micro test combined with theory analysis as the means, use" Test - Analysis - Modeling - Verification" as research ideas, explore quantitative evaluation method of the crack evolution, study surface crack evolution law of expansive soil through the digital photography、3D laser scanner and digital-image processing method, study three-dimensional spatial distribution characteristics of expansive soil crack through CT scan test, study microstructure change on expansive soil after drying through MIP and SEM, explain the producing condition and damage evolution law and evolution mechanism of expansive soil fracture from the micro perspective and combining macroscopic test, establish macro - micro constitutive relationship of the crack evolution. The expansive soil is a typical fracture - pore dual medium after cracking, its characteristics of the seepage has obvious difference from the general double porous media, so infiltration model test will be done to soil samples with different crack extension state using water and hydrophobic liquid, analysis the of the differences of the results, understand seepage characteristics of fissure expansive soil in-depth, reference the basic framework of dual porous medium theory, establish seepage constitutive model of non-saturated expansion soil considering the effect of the crack, and find out its parameter determines method. The results of research will provide theoretical basis and technical support for the assessment of slope disaster and the slope protection theory and design on expansive soil slope ,have far-reaching significance to comprehensively grasp the engineering properties of expansive soil and to promote the development of theories of unsaturated soils.

项目以膨胀土边坡稳定与防护工程为背景，以典型地区膨胀土为研究对象，采用宏微观试验与理论分析结合的手段，运用“试验一分析一建模一验证”的研究思路，提出裂隙演化定量评价方法，基于数码摄影、三维激光扫描仪结合数字图像处理方法研究膨胀土表面裂隙演化规律，通过CT扫描试验研究膨胀土裂隙的三维空间分布特征，采用压汞试验和电镜扫描测试相结合的方法研究膨胀土脱湿过程中微结构变化，从微观角度入手结合宏观试验结果阐述膨胀土裂隙的产生条件与损伤破坏演化规律及其演化机理，建立裂隙演化宏-微观的本构关系。对于不同裂隙扩展状态土样分别采用水与疏水性液体进行入渗模型试验，分析结果的差异性，深入认识裂隙膨胀土的渗流特性，借鉴双重孔隙介质理论基本框架，建立考虑裂隙作用的非饱和膨胀土渗流本构模型，项目研究成果将为膨胀土边坡灾害评估及坡面防护理论与设计提供理论依据和技术支持，有深远的现实意义。

项目以膨胀土边坡稳定与防护工程为背景，以典型地区膨胀土为研究对象，采用宏微观试验与理论分析结合的手段，运用“试验一分析一建模一验证”的研究思路，提出裂隙演化定量 评价方法，基于数码摄影、三维激光扫描仪结合数字图像处理方法研究膨胀土表面裂隙演化规 律，通过CT扫描试验研究膨胀土裂隙的三维空间分布特征，采用压汞试验和电镜扫描测试相结合的方法研究膨胀土脱湿过程中微结构变化，从微观角度入手结合宏观试验结果阐述膨胀土裂隙的产生条件与损伤破坏演化规律及其演化机理，以膨胀土内部微观孔隙为对象，采用孔隙分维模型和计算方法，探明膨胀土内部孔径的划分标准，采用三种分形维数的计算方法对各种计算方法进行比较，说明其优劣，进行裂隙膨胀土微观结构分形维数计算分析。建立裂隙演化宏-微观的本构关系。对于不 同裂隙扩展状态土样分别采用水与疏水性液体进行入渗模型试验，分析结果的差异性，深入认识裂隙膨胀土的渗流特性，借鉴双重孔隙介质理论基本框架，建立考虑裂隙作用的非饱和膨胀土渗流本构模型，项目研究成果将为膨胀土边坡灾害评估及坡面防护理论与设计提供理论依据和技术支持，有深远的现实意义。