本文選題：凍結粉質黏土　切入點：三軸試驗　出處：《哈爾濱理工大學》2017年碩士論文　論文類型：學位論文

【摘要】：作為世界第三凍土分布大國,我國境內凍土分布廣泛。“一帶一路”戰(zhàn)略和京津冀、“東北-蒙東經(jīng)濟區(qū)”戰(zhàn)略的提出,幾乎將我國凍土分布區(qū)域全部納入其中。在經(jīng)濟飛速發(fā)展的前提下,國家必將對道路等交通基礎設施建設投入大量人力物力;同時,公路運輸呈現(xiàn)的多輪軸、重載化趨勢也將增加道路的災害風險。凍土作為一種復雜地質體,無疑會對道路安全運營產(chǎn)生嚴重威脅。本文以我國寒區(qū)凍土路基抗剪強度特性為應用背景,選取粉質黏土為研究對象,基于低溫靜三軸試驗和理論分析等方法,研究粉質黏土的負溫抗剪強度特性,并構建考慮溫度、試樣初始含水率的抗剪強度模型。主要研究工作如下:1.分析了凍土三軸試驗中出現(xiàn)的溫度控制困難、加載桿易凍結及圍壓補給受阻等問題的原因,給出了液體降溫、干燥劑吸水、羽絨罩保溫以及更換圍壓管路系統(tǒng)等措施,確保了試驗的順利開展。參考實際工況選取試樣固結圍壓,改進了以往試驗中凍結方式存在的不足,使試驗條件與工程實際更加符合,從而確保結果的可靠性,并縮短了試驗周期。2.不同溫度及初始含水率條件下凍結粉質黏土負溫三軸試驗結果表明:在50kPa圍壓下,偏應力-軸向應變關系呈應變軟化型,且隨溫度降低軟化程度減弱。除個別試驗點,溫度及含水率對試樣軸向破壞應變的影響存在臨界值,在臨界值以下,破壞應變隨溫度降低及含水率的升高而增大;在臨界值以上,結果相反。同一含水率試樣,其初始切線模量隨溫度降低而增大,但增長趨勢逐漸變緩。溫度降低時破壞強度近似線性增長,但破壞強度隨含水率變化存在臨界值。3.通過對試驗數(shù)據(jù)的回歸,建立了抗剪強度與溫度之間的線性回歸模型;通過將模型系數(shù)與含水率之間建立關系,得到了綜合考慮溫度及含水率的抗剪強度模型。誤差分析顯示,利用模型計算結果描述不同溫度及初始含水率狀態(tài)下凍結粉質黏土的抗剪強度較可靠。本文研究成果將對實際工程及相關研究提供一定的借鑒。
[Abstract]:As the third largest country in the world, permafrost is widely distributed in China. The strategy of "Belt and Road", "Beijing-Tianjin-Hebei" and "Northeast Mongolia Economic Zone" is put forward. In the premise of rapid economic development, the state will certainly invest a great deal of manpower and material resources in the construction of transportation infrastructure such as roads. At the same time, the road transportation presents multi-wheeled axles. The trend of heavy loading will also increase the disaster risk of roads. As a complex geological body, frozen soil will undoubtedly pose a serious threat to road safety operation. In this paper, the shear strength characteristics of permafrost roadbed in cold regions of China are taken as the application background. Based on low-temperature static triaxial test and theoretical analysis, the negative temperature shear strength of silty clay is studied, and the temperature is considered. Shear strength model of initial moisture content of sample. The main research work is as follows: 1. The causes of the problems such as difficult temperature control, easy freezing of loading rod and block of confining pressure recharge are analyzed in triaxial test of frozen soil, and the cooling of liquid is given. The measures of desiccant water absorption, down cover insulation and replacement of confining pressure piping system ensure the smooth development of the test. According to the actual working conditions, the sample consolidation confining pressure is selected, and the shortcomings of the freezing method in the previous tests are improved. The test conditions are more consistent with the engineering practice, so as to ensure the reliability of the results, and shorten the test period. 2. The negative temperature triaxial test results of frozen silty clay at different temperatures and initial moisture content show that: under the confining pressure of 50 KPA, The relationship between strain and axial strain is of strain softening type, and the softening degree decreases with the decrease of temperature. Except for a few test points, there is a critical value for the influence of temperature and moisture content on the axial failure strain of the specimen, which is below the critical value. The failure strain increases with the decrease of temperature and the increase of moisture content, but above the critical value, the results are opposite. The initial tangent modulus of the same moisture content sample increases with the decrease of temperature. However, the increasing trend is gradually decreasing. When the temperature decreases, the failure strength increases approximately linearly, but the critical value of the failure strength varies with the moisture content. A linear regression model between shear strength and temperature is established by regression of the test data. By establishing the relationship between the model coefficient and moisture content, the shear strength model considering temperature and moisture content is obtained. The error analysis shows that, It is more reliable to describe the shear strength of frozen silty clay under different temperature and initial moisture content by using the results of model calculation. The research results in this paper will provide some reference for practical engineering and related research.
【學位授予單位】：哈爾濱理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TD713

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