基于BOTDA的预应力混凝土桥墩横梁安全监测技术研究
发布时间：2018-09-09 19:15
【摘要】：分布式光纤传感技术以其巨大的优势已经被研究者应用于诸多的重要结构监测中,而在预应力混凝土桥墩横梁水化热和预应力安全监测中尚属首次,如何在结构中布设光纤、如何提高光纤的存活率以及针对体内预应力钢绞线的分布式监测技术尚有许多的问题并没有得到解决,据此本文进行了如下内容的研究和探索：1、分析比较了传统监测方法的优缺点和分布式光纤技术应用于预应力混凝土桥墩横梁水化热和预应力监测的理论可行性和优势；2、从理论上分析了大体积混凝土温度场的变化机理和预应力钢绞线的应力衰减影响因素,为大体积混凝土水化热三维温度场的建立和预应力钢绞线的模拟提供了理论支持。3、通过现场实验,建立了一整套基于BOTDA技术的预应力混凝土水化热和预应力分布式监测系统；建立了预应力混凝土横梁的可视化三维温度场。4、结合实验现场的光纤布设经验,有效的解决了应变光纤监测体内预应力钢绞线光纤两头引出预应力结构困难的问题。5、利用有限软件建立了预应力混凝土桥墩横梁结构模拟加载的现场情况,分析了不同张拉应力条件下,预应力钢绞线应力的影响范围和大小。基于以上研究工作,取得了如下成果：1、首次实现了基于BOTDA技术的预应力混凝土横梁水化热监测,揭示了预应力混凝土横梁水化热三维温度场的变化规律；2、首次实现了预应力钢绞线的分布式应变监测,揭示了施工过程中多级荷载作用下钢绞线的应力变化过程；3、将传感光纤布设在预应力钢绞线表面,分布式监测体内预应力钢绞线的应力衰减过程,为预应力结构,特别是体内预应力钢绞线结构提供了一种新的监测手段；4、预应力钢绞线在张拉完成后是有一个明显的应力衰减过程的,这个过程所需的时间可能很长,但在张拉完成后一个月内衰减量可以达到衰减总量的75%以上。
[Abstract]:Distributed optical fiber sensing technology has been applied to many important structural monitoring for its tremendous advantages, but it is the first time in the monitoring of hydration heat and prestressing safety of prestressed concrete pier beam. How to lay optical fiber in the structure, how to improve the survival rate of optical fiber and how to distribute prestressed strands in the body are also discussed. There are still many problems that have not been solved in this paper. The following contents are studied and explored in this paper: 1. The advantages and disadvantages of traditional monitoring methods and the theoretical feasibility and advantages of applying distributed optical fiber technology to the monitoring of hydration heat and prestress of prestressed concrete pier beam are analyzed and compared. The variation mechanism of temperature field of mass concrete and the influence factors of stress attenuation of prestressed strand provide theoretical support for the establishment of three-dimensional temperature field of hydration heat of mass concrete and the simulation of prestressed strand. Distributed monitoring system; Visualized three-dimensional temperature field of prestressed concrete crossbeam was established. 4. Combining with the experience of fiber arrangement in the experimental site, the difficulty of prestressing structure at both ends of prestressed steel strand fiber in strain optical fiber monitoring system was effectively solved. 5. The crossbeam junction of prestressed concrete pier was established by using finite software. Based on the above research work, the following achievements have been achieved: 1. Hydration heat monitoring of prestressed concrete beams based on BOTDA technology is realized for the first time, and the three-dimensional temperature of hydration heat of prestressed concrete beams is revealed. 2. Distributed strain monitoring of prestressed strand is realized for the first time, and the stress variation process of strand under multi-stage load is revealed. 3. The sensing fiber is laid on the surface of prestressed strand, and the stress attenuation process of prestressed strand is monitored in a distributed way, which is a prestressed structure, especially the prestressed structure. Prestressed strand structure in vivo provides a new monitoring method; 4. Prestressed strand has an obvious stress attenuation process after tensioning, which may take a long time, but the attenuation can reach more than 75% of the total attenuation within one month after tensioning.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U447
本文编号：2233317
[Abstract]:Distributed optical fiber sensing technology has been applied to many important structural monitoring for its tremendous advantages, but it is the first time in the monitoring of hydration heat and prestressing safety of prestressed concrete pier beam. How to lay optical fiber in the structure, how to improve the survival rate of optical fiber and how to distribute prestressed strands in the body are also discussed. There are still many problems that have not been solved in this paper. The following contents are studied and explored in this paper: 1. The advantages and disadvantages of traditional monitoring methods and the theoretical feasibility and advantages of applying distributed optical fiber technology to the monitoring of hydration heat and prestress of prestressed concrete pier beam are analyzed and compared. The variation mechanism of temperature field of mass concrete and the influence factors of stress attenuation of prestressed strand provide theoretical support for the establishment of three-dimensional temperature field of hydration heat of mass concrete and the simulation of prestressed strand. Distributed monitoring system; Visualized three-dimensional temperature field of prestressed concrete crossbeam was established. 4. Combining with the experience of fiber arrangement in the experimental site, the difficulty of prestressing structure at both ends of prestressed steel strand fiber in strain optical fiber monitoring system was effectively solved. 5. The crossbeam junction of prestressed concrete pier was established by using finite software. Based on the above research work, the following achievements have been achieved: 1. Hydration heat monitoring of prestressed concrete beams based on BOTDA technology is realized for the first time, and the three-dimensional temperature of hydration heat of prestressed concrete beams is revealed. 2. Distributed strain monitoring of prestressed strand is realized for the first time, and the stress variation process of strand under multi-stage load is revealed. 3. The sensing fiber is laid on the surface of prestressed strand, and the stress attenuation process of prestressed strand is monitored in a distributed way, which is a prestressed structure, especially the prestressed structure. Prestressed strand structure in vivo provides a new monitoring method; 4. Prestressed strand has an obvious stress attenuation process after tensioning, which may take a long time, but the attenuation can reach more than 75% of the total attenuation within one month after tensioning.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U447
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