本文選題：粉質(zhì)粘土　切入點(diǎn)：凍融循環(huán)　出處：《東北電力大學(xué)》2017年碩士論文

【摘要】：在國(guó)家進(jìn)行改革開放的進(jìn)程中,東北地區(qū)的經(jīng)濟(jì)建設(shè)工作有了飛速的發(fā)展,其中公路、鐵路、水利水電等基礎(chǔ)設(shè)施的建設(shè)當(dāng)為重中之重。土作為所有工程的基礎(chǔ),其物理性質(zhì)及力學(xué)性質(zhì)在東北地區(qū)特殊氣候特征條件下的穩(wěn)定性和安全性對(duì)構(gòu)筑物至關(guān)重要。季凍土冬季凍結(jié)成冰,夏季融化,受到冷生作用的影響,季凍土體在凍結(jié)融化過(guò)程后的力學(xué)性質(zhì)會(huì)與未經(jīng)凍融的土體有著巨大的改變。所以,在對(duì)季節(jié)性凍土區(qū)域的工程進(jìn)行安全和穩(wěn)定性的評(píng)價(jià)時(shí),一定要考慮經(jīng)過(guò)凍結(jié)合融化的土體在內(nèi)部結(jié)構(gòu)方面所發(fā)生的變化�，F(xiàn)在人們對(duì)我國(guó)東北地區(qū)季凍土的物理力學(xué)性質(zhì)的理論和試驗(yàn)研究都相對(duì)薄弱,本文改良真空預(yù)壓法制備飽和土,自制低溫三軸試驗(yàn)機(jī)。隨后以吉林地區(qū)粉質(zhì)粘土為研究對(duì)象,針對(duì)淺土層工況和深土層工況對(duì)于季凍土力學(xué)效應(yīng)不同需求,分別進(jìn)行季凍土預(yù)凍融試驗(yàn)和正凍融試驗(yàn),針對(duì)土在經(jīng)歷不同初始條件后的力學(xué)效應(yīng)進(jìn)行研究,也闡述了再兩種不同荷載模式下凍融循環(huán)作用對(duì)吉林地區(qū)粉質(zhì)粘土工程性質(zhì)的影響規(guī)律,主要的工作內(nèi)容如下:1、本文詳細(xì)介紹了國(guó)內(nèi)、外對(duì)于季節(jié)性凍土經(jīng)歷凍融循環(huán)作用后的物理力學(xué)性質(zhì)影響規(guī)律的研究現(xiàn)狀,并分析了目前國(guó)內(nèi)、外對(duì)于能夠進(jìn)行凍融試驗(yàn)的設(shè)備現(xiàn)狀。2、對(duì)吉林地區(qū)的季節(jié)性凍土進(jìn)行常規(guī)物性指標(biāo)試驗(yàn),確定吉林地區(qū)土體的基本特性,進(jìn)而研究土體的凍融特性,并介紹其基本相關(guān)參數(shù),了解制約土體物理力學(xué)性質(zhì)的彈性模量理論研究。3、改進(jìn)了真空預(yù)壓法,制備出飽和土試樣,并且驗(yàn)證了土樣的合理性,節(jié)約土體飽和時(shí)間,兼顧制造費(fèi)用且土樣均勻飽和程度高,適合獲取大量試驗(yàn)土樣。4、針對(duì)淺土層工況進(jìn)行無(wú)側(cè)限壓力凍結(jié)的預(yù)凍融三軸試驗(yàn);分別對(duì)不同凍結(jié)溫度(-3、-7、-12℃)和不同凍融循環(huán)次數(shù)(0~9次)的試樣進(jìn)行不同圍壓(100、200、300、400kPa)的三軸剪切試驗(yàn),得到了各個(gè)土樣在不同初始條件下的應(yīng)力-應(yīng)變曲線,分別對(duì)各試樣的粘聚力、內(nèi)摩擦角等抗剪強(qiáng)度參數(shù)進(jìn)行對(duì)比分析,分析在預(yù)凍融試驗(yàn)?zāi)Ｊ较鲁跏紬l件與試驗(yàn)結(jié)果的內(nèi)在聯(lián)系。5、針對(duì)深土層工況進(jìn)行“邊施加圍壓邊對(duì)土樣進(jìn)行凍結(jié)融化”的正凍融三軸試驗(yàn),分別對(duì)不同凍結(jié)溫度(-3、-7、-12℃)和不同凍融循環(huán)次數(shù)(0~9次)的試樣進(jìn)行三軸剪切試驗(yàn),通過(guò)對(duì)各組實(shí)驗(yàn)結(jié)果進(jìn)行對(duì)比分析,總結(jié)不同初始條件與試驗(yàn)結(jié)果的影響規(guī)律。
[Abstract]:In the process of reform and opening to the outside world, the economic construction in Northeast China has developed rapidly. The construction of infrastructure such as highway, railway, water conservancy and hydropower should be the most important. Soil is the foundation of all projects. The stability and safety of its physical and mechanical properties under the special climatic conditions in Northeast China are very important to the structure. The seasonal frozen soil freezes in winter and melts in summer, which is affected by cold generation. The mechanical properties of the seasonal frozen soil body after freezing and thawing will change greatly with the unfrozen soil mass. Therefore, in the evaluation of the safety and stability of the engineering in the seasonal frozen soil area, We must take into account the changes in the internal structure of the frozen and thawed soils. Nowadays, the theoretical and experimental studies on the physical and mechanical properties of the seasonal frozen soils in northeast China are relatively weak. In this paper, the saturated soil is prepared by the improved vacuum preloading method, and the low temperature triaxial test machine is made. Then, the silty clay in Jilin area is taken as the research object, according to the different demands for the mechanical effect of the seasonal frozen soil under the shallow and deep soil conditions. The pre-freeze-thaw test and the positive freeze-thaw test were carried out respectively, and the mechanical effects of the soil under different initial conditions were studied. The influence of freeze-thaw cycle on the engineering properties of silty clay in Jilin area under two different load modes is also described. The main work is as follows: 1. The current research status of physical and mechanical properties of seasonal frozen soil after freeze-thawing cycle is studied, and the current domestic situation is analyzed. For the equipment that can carry out freeze-thaw test, the conventional physical property index test of seasonal frozen soil in Jilin area is carried out to determine the basic characteristics of soil mass in Jilin area, and then to study the freeze-thaw characteristic of soil mass, and to introduce its basic parameters. The theoretical study of modulus of elasticity, which restricts the physical and mechanical properties of soil, is studied. The vacuum preloading method is improved to prepare the saturated soil sample, and the rationality of the soil sample is verified, and the saturation time of the soil is saved. Considering the cost of manufacturing and the high uniform saturation degree of soil samples, it is suitable to obtain a large number of test soil samples .4, and carry out pre-freezing and thawing triaxial tests without lateral pressure freezing for shallow soil conditions. The triaxial shear tests of samples with different freezing temperatures (-3 ~ 3 ~ 7 ~ 7 ~ 12 鈩，

本文編號(hào)：1675212