内压作用下PCCP变形光纤监测技术研究

发布时间：2019-01-03 16:25

【摘要】：预应力钢筒混凝土管(PCCP)在区域性调水、市政给排水等国家基础建设中发挥着重要的作用。PCCP作为一种复合管材,由于铺设距离长,穿越区域工程地质条件复杂,其在长期运营过程中的结构安全性一直是重点关注的课题。管道监测是PCCP结构安全状态评估及预防爆管等的基础,传统的监测技术难以实现PCCP在内压作用下的多层结构分布式、长距离、实时动态监测。本文以南水北调工程为背景,探索性地将光纤光栅技术(FBG)和脉冲预泵浦布里渊光时域分析仪技术(PPP-BOTDA)应用于PCCP结构变形监测,开展了 PCCP光纤监测关键技术研究,对PCCP管道原型5层结构在内压作用下和断丝后的结构应变响应规律进行了监测;在此基础上,利用有限元软件ABAQUS建立了 PCCP管道三维非线性有限元模型,模拟了管道在不同内水压下的结构变形,并与光纤监测结果进行了对比分析。论文取得如下成果:(1)总结了 PCCP失效模式及管道监测技术,分析了各种监测技术存在的局限性;介绍了基于PPP-BOTDA和FBG光纤感测技术的基本原理、技术特点及适用范围,论证了其应用于PCCP管道变形监测的可行性。(2)对基于FBG和PPP-BOTDA的PCCP光纤监测关键技术进行了试验研究,包括仪器的解调性能、温度补偿技术、布设工艺等;研发了适合混凝土和砂浆应变分布式监测的CFRP传感布;对课题组研发的基于FBG技术的渗压计、温度传感器、贴片式应变计开展了一系列的温度和应变系数标定试验;采用等强度梁,开展了钢结构表面多种光纤应变传感器测试性能试验,结果表明FBG贴片式应变计和0.9mm聚酰亚胺光纤具有更好的应变测试性能,并分析了点焊和环氧粘贴两种安装工艺对FBG贴片式应变计应变传递的影响。(3)设计了内水压作用下PCCP管道各层结构应变监测方案,包括光纤传感器的选型、安装工艺及线路的集成,建立了 PCCP结构应变光纤监测系统。(4)开展了 PCCP现场原型试验,对管道混凝土、钢筒、钢丝及砂浆层在内压作用下和断丝后的结构应变进行了监测。监测结果能全面、形象直观地反映PCCP在加压和断丝过程中的应变响应规律。基于监测数据的分析,把管道变形过程分为三个阶段:管道各层结构变形协调一致阶段(0～1.8MPa),应变与内水压呈良好的线性关系;管道初裂阶段(1.9MPa)。钢丝和钢筒屈服阶段(1.9～2.25MPa),此阶段内水压力主要由预应力钢丝承担。并且获得了预应力钢丝断裂后,自身应变响应规律以及对旁侧未断钢丝和钢筒变形的影响。(5)基于ABAQUS建立了 PCCP三维非线性有限元计算模型,计算了管道在不同内水压下的结构变形,并将计算结果与光纤监测结果进行了对比分析,结果表明光纤监测值和PCCP有限元模拟值有的一致性较好,变化趋势相似。进一步验证了光纤感测技术在PCCP管道结构应变监测上的可行性和有效性。
[Abstract]:Prestressed steel cylinder concrete pipe (PCCP) plays an important role in regional water transfer, municipal water supply and drainage and other national infrastructure. As a kind of composite pipe, PCCP is a kind of composite pipe. The structural safety in the long-term operation process has been the focus of attention. Pipeline monitoring is the basis of PCCP structure safety state evaluation and tube explosion prevention. Traditional monitoring technology is difficult to realize distributed, long distance and real-time dynamic monitoring of multi-layer structure under the action of internal pressure of PCCP. In this paper, based on the South-to-North Water transfer Project, fiber Bragg grating (FBG) technology and pulse prepumped Brillouin optical time domain analyzer (PPP-BOTDA) are applied to PCCP structure deformation monitoring, and the key techniques of PCCP fiber monitoring are studied. The strain response law of PCCP pipeline prototype structure under internal pressure and after broken wire is monitored. On this basis, the three-dimensional nonlinear finite element model of PCCP pipeline is established by using the finite element software ABAQUS, and the structural deformation of the pipeline under different internal water pressures is simulated, and the results are compared with the results of optical fiber monitoring. The main achievements are as follows: (1) the failure mode and pipeline monitoring technology of PCCP are summarized, and the limitations of various monitoring technologies are analyzed. This paper introduces the basic principle, technical characteristics and application scope of optical fiber sensing technology based on PPP-BOTDA and FBG. The feasibility of its application in PCCP pipeline deformation monitoring is demonstrated. (2) the key techniques of PCCP optical fiber monitoring based on FBG and PPP-BOTDA are experimentally studied, including demodulation performance of the instrument, temperature compensation technology, laying process and so on. The CFRP sensing cloth suitable for distributed monitoring of concrete and mortar strain was developed, and a series of calibration tests of temperature and strain coefficient were carried out for the seepage gauge, temperature sensor and patch strain gauge based on FBG technology developed by the research group. The testing performance tests of various optical fiber strain sensors on steel structure surface were carried out by using equal strength beam. The results show that FBG strain gauge and 0.9mm polyimide fiber have better strain testing performance. The effect of spot welding and epoxy bonding on the strain transfer of FBG strain gauge is analyzed. (3) the strain monitoring scheme of each layer of PCCP pipeline under the action of internal water pressure is designed, including the type selection of optical fiber sensor. With the integration of installation technology and circuit, the PCCP structural strain fiber monitoring system was established. (4) the PCCP prototype test was carried out to monitor the structural strain of pipeline concrete, steel cylinder, steel wire and mortar layer under internal pressure and after breaking wire. The monitoring results can reflect the strain response of PCCP in the process of compression and wire breaking. Based on the analysis of monitoring data, the pipeline deformation process is divided into three stages: the coherent deformation phase (0~1.8MPa) of each layer of pipeline, the linear relationship between strain and internal water pressure, and the initial crack stage (1.9MPa) of pipeline. In steel wire and cylinder yield stage (1.9~2.25MPa), water pressure is mainly borne by prestressed steel wire. The strain response law of prestressed steel wire and its influence on the deformation of unbroken steel wire and cylinder are obtained. (5) based on ABAQUS, the three-dimensional nonlinear finite element model of PCCP is established. The structural deformation of pipeline under different internal water pressure is calculated, and the calculated results are compared with the results of optical fiber monitoring. The results show that there is good consistency between the fiber monitoring values and the PCCP finite element simulation values, and the variation trend is similar. The feasibility and effectiveness of optical fiber sensing technology in strain monitoring of PCCP pipeline structure are further verified.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV672.2;TV221

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