荷载与海洋环境耦合作用下海工混凝土结构耐久性研究

发布时间：2018-07-27 09:12

【摘要】：钢筋混凝土结构物因过早发生性能退化而缩减其服役寿命,往往不是由于强度不够,而是因为其耐久性不足。目前国内外对单一环境因素如氯离子侵入、碳化导致的混凝土结构耐久性劣化已有较成熟的研究。但值得注意的是,实际环境中混凝土因耐久性不良服役性能下降大多是荷载、环境和气候等多因素协同作用的结果,这必然与单一环境因素下的混凝土结构劣化规律有显著差异。环境与荷载耦合作用也不是各单因素作用的简单叠加,为深入揭示荷载与环境耦合作用对海工混凝土结构宏观性能劣化的影响机理,有必要研究荷载与海洋环境下混凝土中氯离子的渗透性及其变化规律,建立混凝土结构内部微变化与耐久性宏观劣化之间的相互联系。本文开展荷载与海洋环境耦合作用下海工混凝土结构耐久性研究,对码头正常使用条件下钢筋混凝土结构构件荷载水平进行了调研与分析,研发了新型荷载与氯盐侵蚀环境同步耦合设备系统,并应用于疲劳荷载作用下的海工混凝土结构氯离子侵入试验研究,对比静载下的混凝土氯离子侵入规律,揭示了疲劳荷载对混凝土氯离子渗透的量化影响规律,并应用于混凝土结构耐久性寿命预测中。本文的主要研究内容及结论如下:(1)采用理论计算和现场实际监测相结合的方法,以华南地区码头工程实例为调查对象,分析高桩码头典型梁体构件使用过程中的荷载状态与内力,结果表明若不考虑构件自重的影响,码头使用状态下构件荷载水平的取值约为0.1~0.47之间。(2)研制出动荷载与海洋环境同步耦合试验设备系统,该设备系统可提供多种频率与加载方式的交变荷载,能较真实地模拟海工建筑物在荷载与环境“同时耦合作用”的服役环境,实现了动荷载与氯盐侵蚀环境的同步耦合作用。(3)应用研制的动荷载与海洋环境同步耦合试验设备系统,进行了钢筋混凝土的荷载与氯盐环境的耦合试验(荷载水平分别为0.5、0.3、0.15,加载频率分别为2Hz、5Hz、10Hz,喷洒与加载同时开始同时结束,喷洒量约为15L/h),研究荷载和腐蚀同时作用下钢筋混凝土结构内氯盐渗透规律,揭示了交变荷载对混凝土结构耐久性劣化机理。(4)通过对已完成耦合试验的试件纯弯段取样进行氯离子含量测定,研究荷载与腐蚀耦合作用下氯离子侵蚀机理及其模型,分析不同荷载水平、不同加载频率作用下氯离子的传输行为,探索荷载与环境耦合因素之间的相互作用,获得了氯离子扩散系数的荷载影响因子,进而对原有氯离子渗透模型进行了修正。(5)通过对耦合作用后的构件进行内部损伤CT扫描试验,运用各种图像处理方法和分析手段,探索混凝土裂纹形态及其演化规律,找出损伤情况与荷载大小、加载时间的关系,确立基于海洋盐雾环境和荷载作用下的混凝土损伤规律,探索了混凝土细观损伤演化过程的机理及其对耐久性退化规律的影响。(6)基于试验研究成果,对以可靠度理论为基础而建立的腐蚀诱导期的钢筋混凝土结构耐久性寿命模型中的关键参数进行了修正,建立了疲劳荷载与海洋环境多因素耦合作用下的混凝土结构耐久性寿命预测模型,利用该模型对高桩码头的横梁结构进行了耐久性寿命计算,计算结果与实际情况较为吻合,并将耐久性寿命模型用于码头结构构件的耐久性寿命设计。
[Abstract]:The service life of reinforced concrete structures is reduced due to premature performance degradation, which is often not due to insufficient strength, but because of their lack of durability. At present, there is a mature research on the deterioration of the durability of concrete structures caused by single environmental factors such as chloride ion invasion and carbonization. The decrease in durability of concrete due to poor durability is mostly the result of multiple factors such as load, environment and climate. It is bound to be significantly different from the law of concrete structure deterioration under single environmental factors. The coupling effect of environment and load is not a simple superposition of the effects of the single factor, so as to reveal the coupling of load and environment in depth. It is necessary to study the permeability and change law of chloride ion in concrete under load and marine environment, and establish the interrelation between the internal micro change of concrete structure and the macroscopic deterioration of durability in concrete structure. In the study of soil structure durability, the load level of reinforced concrete structural members under normal conditions of the wharf is investigated and analyzed. A new type of synchronous coupling system with chlorine salt erosion environment is developed and applied to the experimental study of the chlorinated concrete structure under the fatigue load, and the concrete under static load is compared. The law of chlorine ion invasion reveals the quantitative influence of fatigue load on the chloride ion permeability of concrete and applies it to the durability life prediction of concrete structures. The main contents and conclusions of this paper are as follows: (1) the method of combining theoretical calculation with actual monitoring in the field is used to investigate the case of Southern China pier engineering. The load state and internal force of the typical beam components in the high piled wharf are analyzed. The results show that the load level of the component in the wharf is about 0.1~0.47 without considering the influence of the component weight. (2) developing the synchronous coupling test equipment system of the moving load and the marine environment, which can provide a variety of frequencies and various frequencies. The alternating load of loading method can simulate the "simultaneous coupling action" environment of the marine structure in the load and the environment, and realize the synchronous coupling effect of the dynamic load and the chlorine salt erosion environment. (3) the dynamic load and the synchronous coupling test system of the marine environment are used to carry out the load and chlorine salt of the reinforced concrete. The coupling test of the environment (the load level is 0.5,0.3,0.15 respectively, the loading frequency is 2Hz, 5Hz, 10Hz respectively, at the same time the spraying and loading begin to end at the same time, the spraying amount is about 15L/h), to study the chloride penetration law in the reinforced concrete structure under the load and corrosion simultaneously, and reveal the mechanism of the deterioration of the durability of the concrete structure by the alternating load. (4) The chlorine ion content was measured in the pure bending section sample of the completed coupling test. The mechanism and model of the chloride ion erosion under the coupling of load and corrosion were studied. The transmission behavior of chlorine ion under different loading levels and different loading frequencies was analyzed, and the interaction between the coupling factors of load and environment was explored, and chlorine ion was obtained. The influence factor of the load on the diffusion coefficient is modified, and then the original chloride permeability model is corrected. (5) through the internal damage CT scanning test of the members after the coupling, various image processing methods and analysis methods are used to explore the crack morphology and evolution rules of concrete, and to find out the damage situation and load size and the time of loading. In order to establish the damage law of concrete under the ocean salt fog environment and load, the mechanism of concrete meso damage evolution process and its effect on the law of durability degradation are explored. (6) based on the experimental research results, the durability life model of reinforced concrete structure is established on the basis of reliability theory. The key parameters are modified, and the durability life prediction model of concrete structures under the interaction of fatigue load and marine environment is established. The model is used to calculate the durability life of the crossbeam structure of high pile wharf. The calculation results are in good agreement with the actual situation, and the durability life model is used in the dock junction. Durability life design of structural members.
【学位授予单位】：华南理工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TV33

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