海洋环境下水下区预应力混凝土构件氯盐侵蚀效应相似关系研究

发布时间：2018-03-13 13:59

本文选题：预应力混凝土结构　切入点：海洋环境　出处：《江苏大学》2017年硕士论文　论文类型：学位论文

【摘要】：预应力混凝土结构以结构性能好和经济效益高的优点被大量用于海工混凝土结构工程,然而结构构件在海水的长期浸泡和海洋环境侵蚀下耐久性问题日益突出。由于大型工程的建造对资源的消耗量极大,预应力混凝土结构的耐久性问题已经严重制约了我国可持续发展道路,受到了工程界的普遍关注。在国家自然科学基金资助项目“海工预应力混凝土结构耐久性试验相似理论探索与工程应用研究(51278230)”的资助下,本文针对海洋环境水下区预应力混凝土构件在氯盐侵蚀下的耐久性问题,基于混凝土中氯盐侵蚀效应的相似性开展试验研究,探索室内模拟加速试验构件与现场结构构件之间氯盐侵蚀效应的相似关系。主要内容如下:1、完成服役结构的现场检测试验,设计并完成室内模拟加速试验。对连云港墟沟港区69号泊位进行环境调查和耐久性检测,根据调查及检测结果,基于侵蚀效应相似,制定室内模拟试验的侵蚀制度,设计试验室模拟加速的水下区混凝土结构耐久性试验,并对室内试验跟踪检测其侵蚀情况,结果表明室内试验与现场试验具有高度相似性;2、分析试验数据,构建环境与应力耦合作用下的环境-应力-时间相似模型。对现场试验和室内试验的结果分别进行分析,发现氯离子浓度-时间曲线逐渐升高并趋于平缓,水胶比越大,试件氯离子浓度越大,氯离子扩散系数越大,在一定的应力水平内,氯离子浓度和氯离子扩散系数随压应力水平的增加而减小,基于相似理论由Fick第二定律扩散模型推导出环境与应力耦合作用下的环境-应力-时间相似模型,并根据试验数据对相关系数进行修正;3、氯离子侵蚀后的预应力混凝土梁正截面受力性能试验。根据工程结构和环境状况设计预应力混凝土梁并进行室内模拟加速侵蚀试验,在侵蚀一定时间后进行正截面承载力试验,结果表明预应力梁在浸泡溶液中遭受侵蚀与混凝土养护的共同作用,混凝土强度等级为C40的试验梁侵蚀效果显著,承载力明显降低,混凝土强度等级为C50的试验梁在溶液中受到水的养护作用相比溶液侵蚀作用更加明显,其承载力甚至有所提高;4、验证环境-应力-时间相似模型,提出模型应用方法。针对连云港墟沟港区60号泊位在役结构,基于相似理论,制定室内模拟加速试验构件,通过定期检测加速试验构件的侵蚀状况,模拟工程结构的耐久性历程,根据室内模拟加速试验与现场试验的检测结果,计算得到时间相似系数λ_t=10.95,氯离子侵蚀深度的相似系数λ_x=2.49。
[Abstract]:Prestressed concrete structures are widely used in marine concrete structures because of their good structural performance and high economic benefits. However, the durability of structural members is becoming more and more serious due to the long-term immersion of seawater and the erosion of marine environment. The durability of prestressed concrete structures has seriously restricted the sustainable development of our country. Under the support of the National Natural Science Foundation of China, the National Natural Science Foundation of China, supported by the National Natural Science Foundation of China, supported by the similar Theory Exploration and Engineering Application Research on the durability Test of Marine Prestressed concrete structures (51278230), Aiming at the durability of prestressed concrete members under chloride erosion in the underwater area of marine environment, based on the similarity of chloride erosion effect in concrete, the experimental study is carried out in this paper. To explore the similarity of chloride erosion effect between indoor simulated accelerated test components and field structural components. The main contents are as follows: 1. The indoor simulation accelerated test was designed and completed. The environmental investigation and durability test of berth 69 in Xugou Port area of Lianyungang were carried out. According to the results of investigation and test, based on the similar erosion effect, the erosion system of indoor simulation test was established. The durability test of concrete structure in underwater area is simulated and accelerated in the laboratory. The results show that the indoor test has a high similarity with the field test, and the test data are analyzed, and the results show that the indoor test has a high similarity with the field test. The environment-stress-time similarity model under the coupling of environment and stress was constructed. The results of field and laboratory tests were analyzed, and it was found that the concentration-time curve of chloride ion gradually increased and tended to be gentle, and the ratio of water to binder increased. The larger the chloride concentration, the greater the chloride diffusion coefficient. In a certain stress level, the chloride ion concentration and chloride diffusion coefficient decrease with the increase of compressive stress level. Based on the similarity theory, the environment-stress-time similarity model under the coupling of environment and stress is derived from the diffusion model of Fick's second law. According to the experimental data, the correlation coefficient is corrected and the stress behavior of the normal section of prestressed concrete beam after chloride ion erosion is tested. The prestressed concrete beam is designed according to the engineering structure and environmental conditions, and the indoor simulated accelerated erosion test is carried out. After a certain time of erosion, the bearing capacity of the normal section is tested. The results show that the concrete strength grade C40 of the test beam with concrete strength grade C40 has a remarkable erosion effect, and the bearing capacity is obviously reduced. The concrete strength grade C50 test beam is more obviously affected by water curing in solution than by solution erosion, and its bearing capacity is even increased by 4%, which verifies the environment-stress-time similarity model. According to the existing structure of No. 60 berth in Xugou Port area of Lianyungang, based on the similarity theory, the indoor simulated accelerated test components are developed, and the erosion status of accelerated test members is regularly detected. According to the results of indoor and field tests, the time similarity coefficient 位 _ T _ T _ (10.95) and the similarity coefficient of chloride ion erosion depth 位 _ (x _ x) _ (2.49) are calculated for simulating the durability history of engineering structures.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV332

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