【摘要】：黏土地基受擾動(dòng)后土體強(qiáng)度會(huì)發(fā)生衰減,嚴(yán)重時(shí)將導(dǎo)致建(構(gòu))筑物的破壞。由于擾動(dòng)形式的多樣性及土體所處環(huán)境的差異,使得黏土地基(包括固化黏土地基)受擾動(dòng)后強(qiáng)度變化機(jī)理較為復(fù)雜。本文主要通過室內(nèi)試驗(yàn)及理論分析對黏土受不同形式擾動(dòng)后強(qiáng)度變化規(guī)律進(jìn)行研究。通過施加等應(yīng)變循環(huán)扭剪、單剪荷載對原狀黏土進(jìn)行擾動(dòng),得到土體受擾動(dòng)后抗剪強(qiáng)度參數(shù)指標(biāo)。得知黏土受循環(huán)荷載擾動(dòng)后抗剪強(qiáng)度將有所折減,折減程度與荷載幅值、作用次數(shù)正相關(guān);通過MATLAB編程對其微觀圖像定量分析,得知黏土受擾動(dòng)后孔隙的數(shù)量、面積比、圓度增加,等效直徑減小;利用灰色關(guān)聯(lián)度分析動(dòng)后黏土微-宏觀參數(shù),發(fā)現(xiàn)等效直徑對宏觀強(qiáng)度的影響最大,圓度次之,面積比其次,孔隙數(shù)量最小;最后,擬合得到受擾動(dòng)后黏土靜強(qiáng)度變化與微觀參數(shù)之間的函數(shù)關(guān)系。通過室內(nèi)動(dòng)三軸試驗(yàn)開展水泥固化黏土動(dòng)后強(qiáng)度研究。得知固化黏土受動(dòng)應(yīng)力σd擾動(dòng)后無側(cè)限強(qiáng)度qu會(huì)增大,且qu隨σd的增大而增加;研究鹽溶液對水泥土水化反應(yīng)的影響,結(jié)果顯示鹽溶液試樣的qu比正常試樣高,但達(dá)到峰值所用時(shí)間少,鹽溶液養(yǎng)護(hù)下試樣的qu隨齡期的增加而降低;利用電鏡觀察并通過LeicaQwin5000系統(tǒng)定量分析,試樣受擾動(dòng)后,孔隙的數(shù)量、面積比、等效直徑會(huì)減小,而圓度、形態(tài)比會(huì)增大,清水試樣受擾動(dòng)后微觀參數(shù)的絕對變化率比與鹽溶液制樣大。通過上述研究,總結(jié)擾動(dòng)后黏土強(qiáng)度變化規(guī)律;提取影響動(dòng)后黏土靜強(qiáng)度的主要微觀參數(shù),并建立微-宏觀參數(shù)的聯(lián)系,為后續(xù)研究和實(shí)際工程提供技術(shù)支持與理論參考。
[Abstract]:When the clay foundation is disturbed, the strength of the soil will decrease, which will lead to the destruction of the building. Because of the diversity of disturbance forms and the difference of soil environment, the mechanism of strength change of clay foundation (including solidified clay foundation) after disturbance is more complex. In this paper, the strength variation of clay subjected to different forms of disturbance is studied through laboratory tests and theoretical analysis. By applying constant strain cyclic torsion shear and single shear load, the shear strength parameters of undisturbed clay are obtained. It is known that the shear strength of clay will be reduced when disturbed by cyclic load, and the reduction degree is positively related to the amplitude of load and the number of times of action. The quantitative analysis of microcosmic images by MATLAB shows that the number of pores, area ratio, roundness increase and the equivalent diameter decrease after the clay is disturbed. By using grey correlation degree to analyze the micro-macro parameters of the clay, it is found that the equivalent diameter has the greatest influence on the macroscopic strength, the roundness is the second, the area ratio is the second, and the number of pores is the smallest. Finally, the functional relationship between the static strength of the disturbed clay and the microscopic parameters is obtained by fitting. The post-dynamic strength of cement solidified clay was studied by dynamic triaxial test in laboratory. The results show that the unconfined strength qu will increase after dynamic stress 蟽 d disturbance, and the qu will increase with 蟽 d increasing. The effect of salt solution on the hydration reaction of cement soil is studied. The results show that the qu of the salt solution sample is higher than that of the normal sample, but the time to reach the peak value is less, and the qu of the sample decreases with the increase of age under the salt solution curing. Observed by electron microscope and quantitatively analyzed by LeicaQwin5000 system, the number of pores, area ratio and equivalent diameter will decrease, while roundness and morphology ratio will increase when samples are disturbed. The absolute change rate of the microscopic parameters after disturbance is larger than that of salt solution. Through the above research, the change rule of clay strength after disturbance is summarized, the main micro parameters which affect the static strength of clay after disturbance are extracted, and the relationship between micro and macro parameters is established, which provides technical support and theoretical reference for further research and practical engineering.
【學(xué)位授予單位】：中國民航大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU442

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