本文選題：混凝土 + 厚度尺寸效應(yīng)　； 參考：《浙江大學(xué)》2017年碩士論文

【摘要】：混凝土斷裂力學(xué)是在普通斷裂力學(xué)的基礎(chǔ)上發(fā)展起來(lái)的、富有實(shí)用意義的力學(xué)學(xué)科。混凝土斷裂力學(xué)參數(shù)的尺寸效應(yīng)和斷裂過(guò)程區(qū)的表征,是能否建立有效斷裂準(zhǔn)則從而實(shí)現(xiàn)工程應(yīng)用的關(guān)鍵所在,是兩個(gè)重要的理論問(wèn)題。鑒于混凝土斷裂參數(shù)厚度尺寸效應(yīng)研究的不足,作為國(guó)際材料與結(jié)構(gòu)試驗(yàn)室聯(lián)合會(huì)(RILEM)TC265-TDK委員會(huì)為制定雙K斷裂參數(shù)國(guó)際通用規(guī)范而開展的國(guó)際聯(lián)合試驗(yàn)的一部分,本文進(jìn)行了 5組29根變厚度三點(diǎn)彎曲梁的斷裂試驗(yàn),測(cè)算了各試件的雙K斷裂韌度、斷裂能GF等主要斷裂參數(shù),討論了標(biāo)準(zhǔn)計(jì)算方法的合理性,并用歸一化和趨勢(shì)線方法定量表征了各參數(shù)的厚度尺寸效應(yīng)。結(jié)果發(fā)現(xiàn),混凝土雙K斷裂韌度、斷裂能GF以及反映斷裂過(guò)程區(qū)長(zhǎng)度的臨界有效裂縫長(zhǎng)度ac、反映材料脆性的特征長(zhǎng)度lch等均未表現(xiàn)出明顯的厚度尺寸效應(yīng),以最小尺寸試件為標(biāo)準(zhǔn),每增加1倍最小厚度,各參數(shù)的變化幅度均不超過(guò)5%。本文還從斷裂韌度計(jì)算公式、Weibull尺寸效應(yīng)統(tǒng)計(jì)理論和三維考察等方面分析了上述結(jié)果。出于簡(jiǎn)單解析和一般應(yīng)用的考慮,本文結(jié)合混凝土斷裂力學(xué)、特別是雙K斷裂模型的研究成果,在較早期的窄條斷裂區(qū)模型的基礎(chǔ)上,提出了表征微裂縫區(qū)的新模型。該近似模型,基本概念清晰、計(jì)算解析簡(jiǎn)單,關(guān)于黏聚韌度KIcσ和微裂縫區(qū)長(zhǎng)度lF的理論預(yù)測(cè)也獲得了前述斷裂試驗(yàn)的驗(yàn)證,因而可以作為工程實(shí)際應(yīng)用的備選。
[Abstract]:The fracture mechanics of concrete is developed on the basis of ordinary fracture mechanics and has practical significance. The size effect of fracture mechanics parameters of concrete and the characterization of fracture process zone are the key to establish effective fracture criterion and realize engineering application, which are two important theoretical problems. In view of the inadequacies in the study of thickness and size effect of fracture parameters of concrete, as part of the international joint tests carried out by the International Federation of Materials and structure Laboratories, RILEMN TC265-TDK Committee for the formulation of the International General Specification for double K fracture parameters, In this paper, the fracture tests of 29 three-point bending beams with variable thickness have been carried out. The main fracture parameters, such as double K fracture toughness and fracture energy GF, have been calculated, and the rationality of the standard calculation method has been discussed. The thickness and size effect of each parameter is quantitatively characterized by the method of normalization and trend line. The results show that the double K fracture toughness, fracture energy GF, critical effective crack length acand the characteristic length of material brittleness lch do not show significant thickness size effect. With the minimum size specimen as the standard, the variation range of each parameter is not more than 5 for every increase of the minimum thickness. The above results are also analyzed from the statistical theory of Weibull size effect and three dimensional investigation. For the sake of simple analysis and general application, based on the research results of concrete fracture mechanics, especially the double K fracture model, and on the basis of the earlier narrow strip fracture zone model, a new model for characterizing the microfracture zone is proposed in this paper. The basic concept of the approximate model is clear and the calculation is simple. The theoretical prediction of the cohesion toughness KIc 蟽 and the length of the micro-fracture zone L _ F has also been verified by the fracture test mentioned above, so it can be used as an alternative for practical engineering application.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TU528

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本文編號(hào)：1809872