發(fā)布時(shí)間：2018-11-06 15:19

【摘要】：分散性土是近年來(lái)巖土工程界備受關(guān)注的特殊土類之一,它具有抗沖蝕能力很低的特點(diǎn),極易對(duì)水利工程造成危害。針對(duì)傳統(tǒng)判別分散性土的試驗(yàn)方法繁瑣,且判別結(jié)果之間往往出現(xiàn)相互矛盾等缺點(diǎn),本文基于土力學(xué)、土壤電學(xué)、土壤物理學(xué)、土壤化學(xué)等理論知識(shí),采用TH2827C數(shù)字交流電橋、針孔試驗(yàn)儀、碎塊試驗(yàn)儀、無(wú)側(cè)限抗壓強(qiáng)度儀和掃描電子顯微鏡,分析了溫度、含水率、孔隙率、飽和度、生石灰摻入量和養(yǎng)護(hù)齡期等因素對(duì)土樣電阻率、分散性、強(qiáng)度和微觀結(jié)構(gòu)的影響。主要研究結(jié)論如下:(1)非分散性土、分散性土的電阻率都隨溫度的升高呈反比例函數(shù)關(guān)系下降;在同一溫度下,非分散性土的電阻率明顯高于分散性土,在低溫條件下(T10℃)表現(xiàn)尤為明顯;可根據(jù)低溫下黏土的電阻率初步判別土樣是否具有分散性。兩種土的電阻率都隨含水率、飽和度的增大呈冪函數(shù)關(guān)系減小,隨孔隙率的增大呈冪函數(shù)或線性關(guān)系增大,但是變化幅度均不同。導(dǎo)致非分散性土、分散性土不同電阻率特性的原因主要在于分散性土的分散機(jī)制、黏粒含量、結(jié)構(gòu)特征等。(2)隨著生石灰摻入量和養(yǎng)護(hù)齡期的增加,分散性土的分散性逐漸減弱直至消失,無(wú)側(cè)限抗壓強(qiáng)度增強(qiáng)。但電阻率隨生石灰摻入量的增加而增大,隨養(yǎng)護(hù)齡期的增加而減少。當(dāng)養(yǎng)護(hù)齡期一定時(shí),改性土的無(wú)側(cè)限抗壓強(qiáng)度與電阻率呈正線性關(guān)系,建立了生石灰改性分散性土的電阻率模型。(3)掃描電鏡分析表明,隨著生石灰摻入量及養(yǎng)護(hù)時(shí)間的增加,改性土顆粒從薄片狀趨于圓潤(rùn),團(tuán)粒體結(jié)構(gòu)逐漸變大,土骨架單元體之間的接觸方式從以點(diǎn)—點(diǎn)接觸和面-面接觸為主轉(zhuǎn)變?yōu)橐悦妗娼佑|為主,土骨架內(nèi)的架空孔隙逐漸減少,顆粒間絮狀物質(zhì)增加,顆粒邊界逐漸模糊,接觸面積逐漸增大,故顆粒間聯(lián)結(jié)作用增強(qiáng)。宏觀上表現(xiàn)為土體的水穩(wěn)性增強(qiáng),分散性土轉(zhuǎn)化為非分散性土,電阻率也發(fā)生變化。(4)基于生石灰改性機(jī)制和Mitchell土的三元導(dǎo)電模型,從微觀結(jié)構(gòu)角度解釋了生石灰改性分散性土電阻率特性變化的原因。
[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，

本文編號(hào)：2314667