發(fā)布時間：2018-02-09 14:02

  本文關(guān)鍵詞： 隧道襯砌 鈣鎂質(zhì)膨脹劑 變形 力學性能 抗裂 有限元分析　出處：《南京航空航天大學》2014年碩士論文　論文類型：學位論文

【摘要】：隧道襯砌作為隧道抵御各類病害的重要屏障,可以防護隧道內(nèi)車輛尾氣對隧道結(jié)構(gòu)的損傷,同時抵御地下水對隧道的侵蝕,并具有一定支護和穩(wěn)定圍巖的作用,對隧道的安全和耐久性能具有重要影響。論文研究了摻鈣鎂質(zhì)膨脹劑襯砌混凝土的力學和變形性能,采用ANSYS有限元分析軟件對混凝土襯砌結(jié)構(gòu)在荷載作用下的應(yīng)力分布進行了仿真分析和數(shù)值模擬,主要研究內(nèi)容和結(jié)論如下:(1)論文對摻鈣鎂質(zhì)膨脹材料襯砌混凝土的力學和抗裂性能進行了試驗研究,結(jié)果表明:膨脹劑在0-5%范圍內(nèi),抗壓強度隨摻量增加而增加,摻量在3.94%-4.73%,混凝土的強度達到最大;在5%-8%范圍內(nèi),抗壓強度隨摻量增加而下降,摻量超過7.1%-7.6%,摻鈣鎂質(zhì)膨脹劑混凝土強度低于未摻的基準混凝土;襯砌混凝土彈性模量隨鈣鎂質(zhì)膨脹劑摻量增加而增加,養(yǎng)護7天,增加的最多,約為7.8%,但增長幅度隨摻量增加逐漸下降,混凝土的抗壓強度與彈性模量呈線性關(guān)系。摻鈣鎂質(zhì)膨脹劑隧道襯砌混凝土的開裂時間晚于未摻的基準混凝土,延遲時間最多達45.1%,混凝土開裂面積減少50%以上,開裂條數(shù)約減少了43%,其抗裂性能高于基準混凝土。(2)論文對不同濕度和約束條件下襯砌混凝土的變形性能進行了分析研究,研究結(jié)果表明:混凝土在不同養(yǎng)護齡期的膨脹量與其所受到的約束程度成反比,摻鈣鎂質(zhì)膨脹劑的鋼筋混凝土變形、限制變形為自由變形在干燥條件下變形量的19.6%和38.6%,對膨脹混凝土施加約束能有效抑制收縮;養(yǎng)護濕度越高,試件變形程度越大,在水中養(yǎng)護的膨脹量較標準養(yǎng)護條件下的約增加了17.2%-20.3%;在大氣中養(yǎng)護的混凝土均呈現(xiàn)收縮變形,但摻膨脹材料的混凝土收縮變形降低,最大減少約25.5%;通過溫度-應(yīng)力試驗研究表明摻鈣鎂質(zhì)膨脹劑混凝土的最大壓力和開裂應(yīng)力較基準襯砌混凝土有明顯提高,應(yīng)力儲備提高至63%,開裂溫度降低約5℃。(3)有限元分析模擬研究表明:在隧道襯砌邊角部位和頂部跨中部位主應(yīng)力較大,最大的軸力發(fā)生在墻的底部,最大的變形出現(xiàn)在底部和頂部的跨中部。摻入鈣鎂質(zhì)膨脹劑后開裂區(qū)域和程度均有所減小。
[Abstract]:As an important barrier against various diseases, tunnel lining can protect the tunnel structure from vehicle exhaust gas, resist the erosion of underground water to the tunnel, and can support and stabilize the surrounding rock to a certain extent. It has an important effect on the safety and durability of tunnel. This paper studies the mechanical and deformation properties of concrete lining with calcium magnesia expansive agent. ANSYS finite element analysis software is used to simulate and simulate the stress distribution of concrete lining structure under load. The main research contents and conclusions are as follows: (1) in this paper, the mechanical and crack resistance properties of the concrete lined with calcium magnesia expansive material are studied. The results show that the compressive strength of the expansive agent increases with the increase of the content of the expansion agent in the range of 0-5%. In the range of 5% -8%, the compressive strength decreases with the increase of the content, and the content exceeds 7.1 -7.6%, and the strength of the concrete doped with calcium magnesia expansive agent is lower than that of the unadulterated standard concrete. The elastic modulus of the lining concrete increases with the increase of the amount of calcium magnesium expansive agent, and the maximum increase is about 7.8% after 7 days of curing, but the increasing range decreases gradually with the increase of the content of calcium magnesium expansive agent. The compressive strength of concrete is linearly related to the modulus of elasticity. The cracking time of tunnel lining concrete with calcium magnesia expansive agent is later than that of unadulterated standard concrete, the delay time is up to 45.1, and the crack area of concrete is reduced by more than 50%. The number of cracking strips is reduced by about 43, and its crack resistance is higher than that of reference concrete.) in this paper, the deformation properties of lining concrete under different humidity and constraint conditions are analyzed and studied. The results show that the expansion of concrete at different curing ages is inversely proportional to the degree of restraint, and the deformation of reinforced concrete with calcium and magnesia expansive agent is inversely proportional. Limiting deformation to 19.6% and 38.6 percent of free deformation under dry conditions, the restraint on expansive concrete can effectively restrain shrinkage, and the higher the curing humidity, the greater the deformation degree of the specimen. The amount of expansion in water curing is increased by 17.2-20.3than that under standard curing condition, the concrete cured in the atmosphere shows shrinkage deformation, but the shrinkage deformation of concrete with expansive material decreases. The results of temperature-stress test show that the maximum pressure and cracking stress of the concrete doped with calcium magnesia expansive agent are obviously higher than that of the standard lining concrete. The finite element simulation study shows that the main stress in the corner of the tunnel lining and the middle part of the top span are larger, and the maximum axial force occurs at the bottom of the wall, the stress reserve is increased to 63 and the cracking temperature is reduced by about 5 鈩，

本文編號：1498097