本文選題：約束收縮 + 混凝土開裂�。� 參考：《哈爾濱工業(yè)大學(xué)》2014年碩士論文

【摘要】：隨著混凝土應(yīng)用范圍的逐漸擴(kuò)大，由于收縮開裂導(dǎo)致的耐久性問題也不斷凸現(xiàn)出來。近年來國內(nèi)外學(xué)者對(duì)混凝土的收縮開裂問題進(jìn)行了大量研究，但大多數(shù)處于采用非約束狀態(tài)評(píng)判和定性化研究階段，因此開展約束狀態(tài)下的混凝土收縮規(guī)律研究與裂縫監(jiān)測(cè)具有重要意義。 首先通過試驗(yàn)測(cè)試了混凝土1d～15d齡期的劈拉強(qiáng)度、立方體抗壓強(qiáng)度和彈性模量等早期基本力學(xué)性能，得出了混凝土早期基本力學(xué)性能隨齡期的發(fā)展規(guī)律曲線。 其次基于毛細(xì)管理論，利用不同齡期鉆取的平板約束條件下的混凝土試樣，通過對(duì)試件進(jìn)行化學(xué)結(jié)合水和孔結(jié)構(gòu)試驗(yàn)，結(jié)合混凝土早期粘彈性模型，對(duì)混凝土約束條件下的早期收縮值進(jìn)行了理論計(jì)算。 再次利用光纖Bragg光柵傳感器，測(cè)試了平板約束條件下混凝土在不同坍落度和風(fēng)速條件下的早期收縮和開裂參數(shù)，研究了混凝土早期收縮開裂應(yīng)力與實(shí)際劈拉應(yīng)力的差異，得出混凝土開裂時(shí)的收縮應(yīng)力僅為同齡期劈拉強(qiáng)度的75%，約束條件下的混凝土收縮開裂是內(nèi)部應(yīng)力累計(jì)造成的。同時(shí)將光纖Bragg光柵傳感器實(shí)測(cè)的收縮值與理論計(jì)算值進(jìn)行比較，發(fā)現(xiàn)采用理論計(jì)算的早期值要大于實(shí)測(cè)值，且兩者的偏差較大，但在3d后兩者的結(jié)果較為接近。 最后通過利用光纖Bragg光柵傳感器監(jiān)測(cè)內(nèi)鋼環(huán)及混凝土環(huán)的應(yīng)變，研究了圓環(huán)約束條件下混凝土環(huán)的早期收縮應(yīng)力發(fā)展規(guī)律和開裂應(yīng)力，結(jié)合混凝土的早期基本力學(xué)性能研究了約束條件下混凝土早期收縮開裂應(yīng)力與實(shí)際劈拉應(yīng)力的差異，發(fā)現(xiàn)混凝土開裂時(shí)的收縮應(yīng)力比同齡期劈拉強(qiáng)度低40%左右；對(duì)比三種約束條件下混凝土早期收縮開裂表明，約束程度越大混凝土早期開裂齡期越短，開裂時(shí)的收縮應(yīng)力也越小，但開裂時(shí)的應(yīng)力水平反卻高。
[Abstract]:With the gradual expansion of concrete application scope, the durability problem caused by shrinkage cracking is also emerging. In recent years, scholars at home and abroad have done a lot of research on shrinkage cracking of concrete, but most of them are in the stage of unconstrained state evaluation and qualitative research. Therefore, it is of great significance to study the shrinkage law and crack monitoring of concrete under constraint state. The early mechanical properties such as splitting tensile strength cube compressive strength and elastic modulus of concrete at 1d~15d age were tested and the development law curve of the early basic mechanical properties of concrete with age was obtained. Secondly, based on the capillary theory, the concrete samples with different ages are used to test the water and pore structure of the specimens, combined with the early viscoelastic model of concrete. The early shrinkage of concrete is calculated theoretically. Using fiber Bragg grating sensor, the early shrinkage and cracking parameters of concrete under different slump and wind speed are tested, and the difference between the early shrinkage cracking stress of concrete and the actual splitting tensile stress is studied. It is concluded that the shrinkage stress of concrete cracking is only 75% of the splitting tensile strength of the same age period, and the shrinkage cracking of concrete under constraint conditions is caused by the accumulative internal stress. At the same time, the measured shrinkage value of fiber Bragg grating sensor is compared with the theoretical calculation value. It is found that the early value of theoretical calculation is larger than the measured value, and the deviation between the two values is large, but after 3 days, the results of the two values are close. Finally, by using fiber Bragg grating sensor to monitor the strain of inner steel ring and concrete ring, the early shrinkage stress development and crack stress of concrete ring under circumscribed conditions are studied. Combined with the early mechanical properties of concrete, the difference between early shrinkage cracking stress and actual splitting tensile stress of concrete under confined conditions is studied. It is found that the shrinkage stress of concrete during cracking is about 40% lower than that of splitting tensile strength of the same age period. Compared with the early shrinkage cracking of concrete under three kinds of restraint conditions, the higher the degree of restraint is, the shorter the early cracking age is, the smaller the shrinkage stress is, but the higher the stress level is during cracking.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TU528

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本文編號(hào)：1912631