分散性土的电阻率特性研究

发布时间：2018-11-06 15:19

【摘要】：分散性土是近年来岩土工程界备受关注的特殊土类之一,它具有抗冲蚀能力很低的特点,极易对水利工程造成危害。针对传统判别分散性土的试验方法繁琐,且判别结果之间往往出现相互矛盾等缺点,本文基于土力学、土壤电学、土壤物理学、土壤化学等理论知识,采用TH2827C数字交流电桥、针孔试验仪、碎块试验仪、无侧限抗压强度仪和扫描电子显微镜,分析了温度、含水率、孔隙率、饱和度、生石灰掺入量和养护龄期等因素对土样电阻率、分散性、强度和微观结构的影响。主要研究结论如下:(1)非分散性土、分散性土的电阻率都随温度的升高呈反比例函数关系下降;在同一温度下,非分散性土的电阻率明显高于分散性土,在低温条件下(T10℃)表现尤为明显;可根据低温下黏土的电阻率初步判别土样是否具有分散性。两种土的电阻率都随含水率、饱和度的增大呈幂函数关系减小,随孔隙率的增大呈幂函数或线性关系增大,但是变化幅度均不同。导致非分散性土、分散性土不同电阻率特性的原因主要在于分散性土的分散机制、黏粒含量、结构特征等。(2)随着生石灰掺入量和养护龄期的增加,分散性土的分散性逐渐减弱直至消失,无侧限抗压强度增强。但电阻率随生石灰掺入量的增加而增大,随养护龄期的增加而减少。当养护龄期一定时,改性土的无侧限抗压强度与电阻率呈正线性关系,建立了生石灰改性分散性土的电阻率模型。(3)扫描电镜分析表明,随着生石灰掺入量及养护时间的增加,改性土颗粒从薄片状趋于圆润,团粒体结构逐渐变大,土骨架单元体之间的接触方式从以点—点接触和面-面接触为主转变为以面—面接触为主,土骨架内的架空孔隙逐渐减少,颗粒间絮状物质增加,颗粒边界逐渐模糊,接触面积逐渐增大,故颗粒间联结作用增强。宏观上表现为土体的水稳性增强,分散性土转化为非分散性土,电阻率也发生变化。(4)基于生石灰改性机制和Mitchell土的三元导电模型,从微观结构角度解释了生石灰改性分散性土电阻率特性变化的原因。
[Abstract]:Dispersive soil is one of the special soils in geotechnical engineering field in recent years. It has the characteristics of low erosion resistance and is easy to cause harm to water conservancy projects. In this paper, based on the theoretical knowledge of soil mechanics, soil electricity, soil physics and soil chemistry, TH2827C digital alternating current bridge is used. Pinhole tester, fragment tester, unconfined compressive strength tester and scanning electron microscope were used to analyze the effects of temperature, water content, porosity, saturation, lime content and curing age on the resistivity and dispersity of soil samples. The influence of strength and microstructure. The main conclusions are as follows: (1) the resistivity of non-dispersible soils decreases inversely with the increase of temperature; At the same temperature, the resistivity of non-dispersible soil is obviously higher than that of dispersed soil, especially at low temperature (T10 鈩，

本文编号：2314667