【摘要】：我國沿海地區(qū)廣泛分布著深厚的海相沉積軟土層,人工地層凍結技術作為一種地層加固技術,可以有效地解決海相軟土強度低、蠕變性、觸變性等工程性質差的難題。但是,在海相軟土層中應用人工地層凍結技術,一方面其熱物理與力學參數(shù)研究較少,缺少相應的基礎數(shù)據(jù),另一方面,人工凍結海相軟土凍脹特性的研究尚處于空白狀態(tài)。為了滿足海相軟土地層應用人工地層凍結技術的需要,本文采用室內試驗、理論推導與數(shù)值模擬相結合的研究方法,對人工凍結條件下海相軟土的凍脹特性開展了一系列研究。首先,通過室內試驗對人工凍結條件下海相軟土的熱物理與力學參數(shù)進行研究。海相軟土由于受到海水的入侵,導致其內部含有一定量的易溶鹽。在對寧波地區(qū)兩種典型的海相軟土層進行室內含鹽量測定的基礎上,研究了海相軟土的起始凍結溫度、導熱系數(shù)、凍土比熱、凍土彈性模量及凍土單軸抗壓強度等熱物理與力學參數(shù),得出了不同影響因素對海相軟土熱物理與力學參數(shù)的影響規(guī)律。其次,通過室內凍脹試驗對人工凍結條件下海相軟土的凍脹特性開展研究。在自行設計并加工的一套簡易的室內凍脹試驗裝置上,開展凍脹率單因素試驗與凍脹率正交試驗。室內凍脹試驗是自下而上一維凍結條件下進行的,測出土體試樣的凍脹量,凍脹率通過計算得到,并得出了含鹽量、含水率、冷端溫度、外部荷載四個因素對海相軟土凍脹率的影響規(guī)律以及四個因素之間的主次關系。同時,通過對凍脹試驗過程中溫度監(jiān)測及凍結后土體試樣不同部位含水率的測量,得出試驗過程中溫度場的發(fā)展規(guī)律與水分重分布的規(guī)律。再者,考慮了海相軟土降溫凍結過程中二次相變的現(xiàn)象,對已有的水分場、鹽分場、溫度場以及應力場方程進行了修正,建立了人工凍結海相軟土水-鹽-熱-力四場耦合的凍脹預報模型。最后,在對已建立的凍脹預報模型進行合理簡化之后,通過有限元數(shù)值模擬軟件COMSOL二次開發(fā)中的PDE模塊,對已建立的凍脹預報模型進行了求解計算,從而實現(xiàn)了對已建立的凍脹預報模型的驗證。將數(shù)值模擬的計算結果與室內凍脹試驗的測量結果進行了對比,二者相互印證了本文對人工凍結條件下海相軟土凍脹特性規(guī)律研究的正確性。
[Abstract]:Deep marine sedimentary soft soil is widely distributed in coastal areas of China. As a kind of stratum strengthening technology, artificial stratum freezing technology can effectively solve the problems of low strength, creep, thixotropy and other engineering properties of marine soft soil. However, in the application of artificial stratum freezing technology in marine soft soil, on the one hand, the study of thermal physical and mechanical parameters is less, and the corresponding basic data is lacking; on the other hand, the research on the frost heave characteristics of artificial frozen marine soft soil is still in blank state. In order to meet the need of applying artificial formation freezing technology in marine soft soil, this paper has carried out a series of research on the frost heave characteristics of marine soft soil under artificial freezing condition by means of laboratory test, theoretical derivation and numerical simulation. Firstly, the thermal physical and mechanical parameters of marine soft soil under artificial freezing condition were studied. Due to the invasion of sea water, marine soft soil contains a certain amount of soluble salt. Based on the indoor measurement of salt content in two typical marine soft soil layers in Ningbo area, the initial freezing temperature, thermal conductivity and specific heat of frozen soil are studied. The thermal physical and mechanical parameters such as elastic modulus of frozen soil and uniaxial compressive strength of frozen soil are obtained. The influence of different factors on the thermal physical and mechanical parameters of marine soft soil is obtained. Secondly, the frost heaving characteristics of marine soft soil under artificial freezing condition are studied by indoor frost heaving test. The single factor test and orthogonal test of frost heave rate were carried out on a set of simple indoor frost heave test device designed and processed by ourselves. The indoor frost heave test was carried out under the condition of one-dimensional freezing from bottom to top. The frost heave quantity of soil sample was measured, and the frost heave rate was calculated, and the salt content, moisture content and cold end temperature were obtained. The influence of four factors of external load on the frost heaving rate of marine soft soil and the primary and secondary relationship between the four factors. At the same time, through the temperature monitoring during the frost heave test and the measurement of moisture content in different parts of the frozen soil sample, the development law of the temperature field and the law of water redistribution during the test process are obtained. Furthermore, considering the phenomenon of secondary phase transition in the process of cooling and freezing of marine soft soil, the existing equations of water field, salt field, temperature field and stress field are modified. The frost heaving prediction model of artificial frozen marine soft soil is established in this paper, which is coupled with water, salt, heat and force. Finally, after reasonable simplification of the established frost heave prediction model, the established frost heave prediction model is solved by the PDE module in the secondary development of the finite element numerical simulation software COMSOL. Thus the verification of the established frost heave prediction model is realized. The calculated results of numerical simulation are compared with the measured results of indoor frost heave test. Both of them confirm the correctness of the research on the frost heave characteristics of marine soft soil under artificial freezing condition.
【學位授予單位】：中國礦業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TU447

【參考文獻】

相關期刊論文 前10條

1 白青波;李旭;田亞護;房建宏;;凍土水熱耦合方程及數(shù)值模擬研究[J];巖土工程學報;2015年S2期

2 張英;邴慧;;含鹽凍土物理力學性質研究現(xiàn)狀與進展[J];冰川凍土;2013年06期

3 王都;孫寧;關鳳宇;;我國城市軌道交通綜合試驗線的建設及其功能[J];現(xiàn)代城市軌道交通;2013年01期

4 張婷;楊平;;人工凍結法在地鐵建設中的應用與發(fā)展[J];森林工程;2012年06期

5 李東慶;周家作;張坤;常法;;季節(jié)性凍土的水-熱-力建模與數(shù)值分析[J];中國公路學報;2012年01期

6 邴慧;馬巍;;鹽漬土凍結溫度的試驗研究[J];冰川凍土;2011年05期

7 劉煥寶;張喜發(fā);趙意民;冷毅飛;;凍土導熱系數(shù)熱流計法模擬試驗及成果分析[J];冰川凍土;2011年05期

8 劉宇亭;唐益群;周潔;閆春嶺;;地鐵隧道工程人工凍結法研究進展[J];低溫建筑技術;2011年09期

9 聶年圣;牛瑞森;;海相軟土成因及其工程特性的研究[J];工程建設與設計;2010年12期

10 甘永德;胡順軍;陳秀龍;;土壤鹽分對土壤水分擴散率的影響[J];水土保持通報;2010年06期

相關博士學位論文 前1條

1 肖朝昀;人工地層凍結凍土帷幕形成與解凍規(guī)律研究[D];同濟大學;2007年

相關碩士學位論文 前6條

1 汪承維;人工凍結鹽漬土導熱系數(shù)試驗研究及其應用[D];安徽理工大學;2014年

2 孫谷雨;南京地鐵典型土層凍土熱物理力學特性研究[D];南京林業(yè)大學;2013年

3 吳剛;巖土材料導熱系數(shù)及水源熱泵室內模擬試驗研究[D];吉林大學;2009年

4 李孝臣;季節(jié)凍土區(qū)高壓輸電桿塔斜面基礎研究[D];哈爾濱工業(yè)大學;2008年

5 于琳琳;不同人工凍結條件下土的凍脹試驗研究[D];哈爾濱工業(yè)大學;2006年

6 冷毅飛;凍土未凍水室內綜合試驗研究[D];吉林大學;2006年

，

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