本文選題：混凝土耐久性 + 多因素耦合作用��； 參考：《中國建筑材料科學研究總院》2014年博士論文

【摘要】：實際服役混凝土結(jié)構(gòu)通常處于復雜的環(huán)境因素作用下，其劣化過程是物理、化學和力學等因素耦合作用的過程，這些因素耦合作用造成的混凝土損傷遠大于各因素單獨作用的疊加。為指導實際工程中混凝土的配合比設計，混凝土耐久性及壽命預測體系的研究趨勢和熱點已由單一因素向多因素耦合作用發(fā)展。然而，以凍融為主因素的多因素耦合作用下的混凝土耐久性研究還顯得不足，存在以下問題：多因素耦合作用下的混凝土耐久性評價還采用以往用于單因素作用下的評價指標，即評價方法相對落后于實際的耐久性研究；現(xiàn)有混凝土損傷模型和壽命預測體系多是基于單因素作用下的；對已經(jīng)取得的成果還缺乏歸納總結(jié)。 為解決上述問題，本文首先開發(fā)了混凝土凍融耐久性數(shù)據(jù)庫系統(tǒng)，對以往學者的試驗數(shù)據(jù)與參考模型進行歸納總結(jié)，以此作為建模的前提基礎之一；然后，用應變表征了多因素耦合作用下混凝土的耐久性能，以此作為建模的另外一個前提基礎；最終，建立了兩個多因素耦合作用下的混凝土損傷模型并結(jié)合壽命預測方法對實際工程進行了壽命評估和預測，為有抗凍要求的服役混凝土耐久性設計和壽命預測研究提供了新思路。本文主要試驗工作及結(jié)果如下： 1）開發(fā)了混凝土凍融耐久性數(shù)據(jù)庫系統(tǒng)。借助于RILEM TC246-TDC技術(shù)委員會平臺，收集到來自15個國家和地區(qū)的34位著名學者關(guān)于多因素耦合作用下混凝土耐久性研究成果以及凍融損傷與壽命預測模型；經(jīng)過嚴格的篩選得到入庫試驗數(shù)據(jù)和模型，并與計算機技術(shù)相結(jié)合，打造了數(shù)據(jù)管理的集成化平臺，具有跨平臺性和可擴展性等優(yōu)點以及查詢和搜索功能。 2）用應變表征了多因素耦合作用下混凝土的耐久性能。無損監(jiān)測的應變具有實時性、連續(xù)性，凍融（簡稱FTC）單因素作用下，混凝土殘余應變的產(chǎn)生證明了混凝土基體的損傷是一個不斷累積的不可逆的劣化過程，它與基體內(nèi)部裂紋的不斷萌生與擴展直接相關(guān)；凍融和鹽溶液侵蝕（簡稱FTC-Cl）雙因素作用下，同一配合比混凝土在3.5wt.%的NaCl溶液中凍融產(chǎn)生的殘余應變比水凍大，，說明鹽溶液加速了混凝土的凍融損傷；凍融、鹽溶液侵蝕和彎曲應力（簡稱FTC-Cl-BS）三因素耦合作用下，施加恒定的彎曲應力比越大，混凝土試件拉應力區(qū)的應變與殘余應變均越大，說明應力的施加加速了混凝土的損傷劣化。 3）建立了混凝土的殘余應變凍融損傷演化方程。在FTC單因素、FTC-Cl雙因素和FTC-Cl-BS三因素耦合作用下，混凝土的殘余應變變化規(guī)律均符合單段或雙段變化模式，單段變化模式一般適用于抗凍性較強的混凝土，雙段變化模式一般適用于抗凍性較差的混凝土；結(jié)合混凝土凍融耐久性數(shù)據(jù)庫系統(tǒng)中其他學者的殘余應變數(shù)據(jù)，對演化方程進行驗證，結(jié)果顯示計算值和實測值之間具有較高的吻合度。 4）建立了基于殘余應變的FTC-Cl雙因素耦合作用下混凝土凍融損傷數(shù)值模型（M-FTC+Cl）。該損傷數(shù)值模型適用于FTC單因素和FTC-Cl雙因素作用，對混凝土損傷程度變量曲線的擬合相關(guān)系數(shù)在0.95以上；該模型還可以預測特定條件下混凝土的最終快速凍融循環(huán)次數(shù)，再結(jié)合壽命預測方法可以預測特定環(huán)境下服役混凝土的安全使用壽命。 5）將凍融損傷、鹽溶液侵蝕等環(huán)境因素進行了力學統(tǒng)一等效轉(zhuǎn)化，建立了基于應變的FTC-Cl-BS三因素耦合作用下混凝土損傷力學模型（M-FTC+Cl+BS）。該損傷力學模型適用于FTC-BS雙因素和FTC-Cl-BS三因素作用，模型建立了應變與快速凍融循環(huán)次數(shù)之間的關(guān)系；利用該模型計算的混凝土最終快速凍融循環(huán)次數(shù)與實際測量值非常接近；該模型結(jié)合壽命預測方法可以預測特定環(huán)境下服役混凝土的安全使用壽命。 6）將凍融損傷模型與實際工程的壽命預測相關(guān)聯(lián)，對實際工程進行了壽命預測。通過計算，長白山飛行區(qū)跑道、停機坪混凝土的使用壽命預測值分別為43年和52年，符合最低設計年限為30年的要求；青島海灣大橋承臺、箱梁混凝土的使用壽命預測值分別為144年、110～123年，也符合設計使用壽命100年的使用要求。
[Abstract]:In order to guide the concrete mix proportion design , the research trend and hot spot of concrete durability and life prediction system have been developed from single factor to multi - factor coupling .
Existing concrete damage models and life prediction systems are based on single factor ;
There is also a lack of inductive summary of the results that have been achieved .

In order to solve the above problems , this paper first develops the concrete freeze - thaw durability database system , summarizes the experimental data and reference model of past scholars , which is one of the preconditions for modeling .
Then , the durability of concrete under multi - factor coupling is characterized by strain , which is another precondition of modeling .
In the end , the concrete damage model under two multi - factor coupling is established and the life prediction method is used to evaluate and predict the life of the practical engineering with the life prediction method . The new idea is provided for the durability design and life prediction of the service concrete with the anti - freezing requirements . The main experimental work and the results are as follows :

1 ) The concrete freeze - thaw durability database system is developed . With the aid of the technical committee of RILE TC246 - TDC , 34 famous scholars from 15 countries and regions are collected , and the research results of durability of concrete under multi - factor coupling and the model of freeze - thaw damage and life prediction are collected .
The data and model of warehousing test are obtained through rigorous screening , and combined with computer technology , the integrated platform for data management is built , which has the advantages of cross - platform and scalability , as well as query and search functions .

2 ) The durability of concrete under multi - factor coupling is characterized by strain . The strain of non - destructive monitoring has the single factor of real - time , continuity and freeze - thaw ( FTC ) .
The residual strain produced by freeze - thawing in 3.5 wt . % NaCl solution was higher than that of the concrete under the action of freeze - thaw and salt solution erosion ( FTC - Cl ) , which indicated that the salt solution accelerated the freeze - thaw damage of concrete ;
Under three factors coupling action of freeze - thaw , salt solution erosion and bending stress ( FTC - Cl - BS ) , the greater the constant bending stress ratio , the greater the strain and residual strain of the tensile stress region of the concrete specimen , and the stress application accelerated the damage of concrete .

3 ) The residual strain freeze - thaw damage evolution equation of concrete is established . Under the coupling action of FTC single factor , FTC - Cl double factor and FTC - Cl - BS , the residual strain law of concrete is in accord with single - section or double - section change mode , and the single - section change mode is generally applicable to concrete with stronger frost resistance , and the double - section change mode is generally applicable to concrete with poor frost resistance ;
Based on the residual strain data of other scholars in the concrete freeze - thaw durability database system , the evolution equation is verified , and the result shows that the calculated value and the measured value have a high degree of coincidence .

4 ) The numerical model ( M - FTC + Cl ) of concrete freeze - thaw damage under the coupling of FTC - Cl with residual strain is established . The damage numerical model is suitable for FTC single factor and FTC - Cl double factors , and the fitting correlation coefficient of the variable curve of damage degree of concrete is more than 0.95 ;
The model can also predict the final quick freeze - thaw cycles of concrete under certain conditions , and the service life of the service concrete in a specific environment can be predicted by combining the life prediction method .

5 ) The mechanical model ( M - FTC + Cl + BS ) of concrete damage under three - factor coupling of strain - oriented FTC - Cl - BS was established . The damage mechanics model was applied to FTC - BS dual - factor and FTC - Cl - BS . The model established the relationship between strain and fast freeze - thaw cycles .
The final fast freeze - thaw cycle of concrete is very close to the actual measured value .
The model combined life prediction method can predict the safe service life of service concrete under certain circumstances .

6 ) The freeze - thaw damage model is associated with the life prediction of the actual project , and the life prediction of the actual project is carried out . Through the calculation , the predicted value of the service life of the runway and apron concrete in Changbai Mountain is 43 years and 52 years respectively , and the minimum design life is 30 years .
The predicted value of the service life of the bearing platform and box girder concrete of Qingdao Bay Bridge is 144 years , 110 - 123 years respectively , and also accords with the use requirements of the design service life of 100 years .

【學位授予單位】：中國建筑材料科學研究總院
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TU528

【參考文獻】

相關(guān)期刊論文 前10條

1 劉崇熙,汪在芹;壩工混凝土耐久壽命的衰變規(guī)律[J];長江科學院院報;2000年02期

2 王永福;大體積混凝土垂直施工縫處裂縫開展的控制[J];電力建設;2002年03期

3 劉建忠;孫偉;繆昌文;劉加平;;彎曲荷載與鹽溶液復合作用下混凝土凍融損傷[J];東南大學學報(自然科學版);2006年S2期

4 慕儒,嚴安,孫偉;荷載作用下高強混凝土的抗凍性[J];東南大學學報;1998年04期

5 汪振雙;宋志晨;;混凝土損傷拋物線模型的建立與壽命預測[J];低溫建筑技術(shù);2009年11期

6 唐杰鋒,吳勝興;大體積混凝土施工期溫度場的仿真計算與監(jiān)測[J];工程質(zhì)量;2002年07期

7 黃孝蘅,許彩虹,王麗文;硬化混凝土中氣泡性質(zhì)對抗凍性影響的試驗研究[J];中國港灣建設;2003年03期

8 蓋國暉;李超;熊建波;王立鋼;王迎飛;;青島海灣大橋海工高性能混凝土配制技術(shù)研究[J];公路;2009年09期

9 ;A MODEL FOR CONCRETE DURABILITY DEGRADATION IN FREEZE-THAWING CYCLES[J];Acta Mechanica Solida Sinica;2003年04期

10 慕儒,繆昌文,劉加平,孫偉;氯化鈉、硫酸鈉溶液對混凝土抗凍性的影響及其機理[J];硅酸鹽學報;2001年06期

相關(guān)博士學位論文 前1條

1 寧作君;凍融作用下混凝土的損傷與斷裂研究[D];哈爾濱工業(yè)大學;2009年

本文編號：1775661