港珠澳大桥混凝土结构耐久性检测与评估研究

发布时间：2018-05-11 23:31

本文选题：港珠澳大桥 + 混凝土结构　；参考：《清华大学》2014年硕士论文

【摘要】：基于港珠澳大桥混凝土耐久性设计,本文开展了现场混凝土质量检测研究,在此基础上完成了港珠澳工程施工阶段各个构件耐久性评估与再设计工作,为工程竣工验收与服役期管理提供了数据支持。本文首先汇总分析了施工现场实验室测得的抗压强度和氯离子扩散系数,以及在预制沉管隧道现场实体构件上无损测得的表面透气性系数、表面电阻率及保护层厚度。分析表明沉管抗压强度和氯离子扩散系数均满足控制规程的质量要求,保护层厚度合格率基本满足预期。沉管表面透气性系数普遍较低,尤其是56d龄期数据,表明预制节段现场混凝土结构致密。表面电阻率符合正态分布,并随混凝土龄期增长呈现出稳定的增大趋势。透气性和电阻率在数值上总体呈负相关,但不足以回归出定量关系。在现场检测数据的基础上,本文对氯盐侵入过程进行了施工阶段的评估。研究回顾了基于氯盐腐蚀的耐久性评估模型,总结分析了模型各个参数的统计特征,考虑了附加防腐蚀措施对模型的影响,在此基础上采用Monte-Carlo方法计算结构各个构件的120年失效概率Pf及可靠指标β,提出了结构初步维护方案和不同工况下的工程建议。计算结果表明大气区和水下区构件的可靠指标较高,可120年免维护;浪溅区构件需要120年耐久性维护预案;收费站暗桥和C匝道桥墩身内部、沉管隧道内部如有海水渗入时,按浪溅区工况计算所得120失效概率超过10%,在这些构件施工与构造中需要重点监测内部海水渗漏过程,并建立相应的耐久性再评估与再设计流程;沉管隧道竣工后如有海水渗入,则需要启动阴极保护措施,启动时间可根据海水渗漏面积比例和预定维护水平计算得到。本文最后进行了耐久性再设计过程研究,并以竣工评估后的沉管隧道的耐久性预案研究、DB02收费站暗桥使用期中的维护方案研究为例展示了耐久性再设计方法。通过计算得出了在三个不同维护水平下,沉管阴极保护启动周期与海水渗入面积比例的关系曲线。并在一组模拟实测暴露数据的基础上,更新了收费站暗桥120年可靠指标及失效概率时变曲线,运用全寿命周期成本方法,确定了水平-2耐久性维护方案为最优方案。
[Abstract]:Based on the concrete durability design of HongKong-Zhuhai-Macao Bridge, this paper carried out the field concrete quality testing research, and completed the durability evaluation and redesign of each component in the construction phase of HongKong-Zhuhai-Macao project. For the completion of the project acceptance and service period management to provide data support. In this paper, the compressive strength and chloride diffusion coefficient measured by the construction site laboratory, the surface permeability coefficient, the surface resistivity and the thickness of the protective layer on the site members of the precast immersed tube tunnel are summarized and analyzed in this paper. The analysis shows that both the compressive strength and the chloride diffusion coefficient of the immersed pipe meet the quality requirements of the control regulations, and the qualified rate of the thickness of the protective layer basically meets the expectation. The permeability coefficient on the surface of the immersed pipe is generally low, especially the 56 d age data, which indicates that the precast segment concrete structure is compact in situ. The surface resistivity obeys the normal distribution and shows a steady increasing trend with the increase of concrete age. There is a negative correlation between permeability and resistivity, but it is not enough to regress the quantitative relationship. Based on the field data, the construction stage of chloride intrusion process is evaluated in this paper. The durability evaluation model based on chloride corrosion is reviewed, the statistical characteristics of each parameter of the model are summarized and analyzed, and the influence of additional corrosion prevention measures on the model is considered. On the basis of this, the 120 year failure probability P f and reliability index 尾 of each component of the structure are calculated by Monte-Carlo method, and the preliminary maintenance scheme of the structure and the engineering suggestions under different working conditions are put forward. The calculation results show that the reliability index of the components in large gas and underwater zones is higher and can be maintained without maintenance for 120 years; the components in the splash zone need 120 years of durability maintenance plans; in the piers of dark bridge and C ramp bridge at toll station, if seawater is infiltrated into the tunnel interior, The failure probability of 120 calculated according to the working condition of the splash area is more than 10. In the construction and construction of these components, it is necessary to monitor the process of internal seawater leakage, and establish the corresponding process of durability re-evaluation and redesign. If seawater seeps into the tunnel after completion, The starting time can be calculated according to the proportion of seawater leakage area and the predetermined maintenance level. At the end of this paper, the durability redesign process is studied, and the durability redesign method is demonstrated by taking the durability plan of the tunnel after completion evaluation as an example. The relation curves between the start-up period of cathodic protection and the proportion of seawater infiltration area were obtained under three different maintenance levels. On the basis of a set of simulated exposure data, the 120 year reliability index and time-varying failure probability curve of hidden bridge in toll station are updated, and the level -2 durability maintenance scheme is determined as the optimal scheme by using the life-cycle cost method.
【学位授予单位】：清华大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U446

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