隧道混凝土衬砌裂缝控制及有限元分析

发布时间：2018-02-09 14:02

  本文关键词： 隧道衬砌 钙镁质膨胀剂 变形 力学性能 抗裂 有限元分析　出处：《南京航空航天大学》2014年硕士论文　论文类型：学位论文

【摘要】：隧道衬砌作为隧道抵御各类病害的重要屏障,可以防护隧道内车辆尾气对隧道结构的损伤,同时抵御地下水对隧道的侵蚀,并具有一定支护和稳定围岩的作用,对隧道的安全和耐久性能具有重要影响。论文研究了掺钙镁质膨胀剂衬砌混凝土的力学和变形性能,采用ANSYS有限元分析软件对混凝土衬砌结构在荷载作用下的应力分布进行了仿真分析和数值模拟,主要研究内容和结论如下:(1)论文对掺钙镁质膨胀材料衬砌混凝土的力学和抗裂性能进行了试验研究,结果表明:膨胀剂在0-5%范围内,抗压强度随掺量增加而增加,掺量在3.94%-4.73%,混凝土的强度达到最大;在5%-8%范围内,抗压强度随掺量增加而下降,掺量超过7.1%-7.6%,掺钙镁质膨胀剂混凝土强度低于未掺的基准混凝土;衬砌混凝土弹性模量随钙镁质膨胀剂掺量增加而增加,养护7天,增加的最多,约为7.8%,但增长幅度随掺量增加逐渐下降,混凝土的抗压强度与弹性模量呈线性关系。掺钙镁质膨胀剂隧道衬砌混凝土的开裂时间晚于未掺的基准混凝土,延迟时间最多达45.1%,混凝土开裂面积减少50%以上,开裂条数约减少了43%,其抗裂性能高于基准混凝土。(2)论文对不同湿度和约束条件下衬砌混凝土的变形性能进行了分析研究,研究结果表明:混凝土在不同养护龄期的膨胀量与其所受到的约束程度成反比,掺钙镁质膨胀剂的钢筋混凝土变形、限制变形为自由变形在干燥条件下变形量的19.6%和38.6%,对膨胀混凝土施加约束能有效抑制收缩;养护湿度越高,试件变形程度越大,在水中养护的膨胀量较标准养护条件下的约增加了17.2%-20.3%;在大气中养护的混凝土均呈现收缩变形,但掺膨胀材料的混凝土收缩变形降低,最大减少约25.5%;通过温度-应力试验研究表明掺钙镁质膨胀剂混凝土的最大压力和开裂应力较基准衬砌混凝土有明显提高,应力储备提高至63%,开裂温度降低约5℃。(3)有限元分析模拟研究表明:在隧道衬砌边角部位和顶部跨中部位主应力较大,最大的轴力发生在墙的底部,最大的变形出现在底部和顶部的跨中部。掺入钙镁质膨胀剂后开裂区域和程度均有所减小。
[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，

本文编号：1498097