基于多模干涉技术的光纤声发射技术用于桥梁沉降监测的研究

发布时间：2018-05-05 22:53

本文选题：桥梁沉降 + 超声波　；参考：《东南大学》2015年硕士论文

【摘要】：桥梁沉降的发生会引起结构损伤,承载力下降,造成一系列严重的灾害事故。因此作为衡量桥梁健康状态的主要参数之一,桥梁沉降是结构监测与分析评估的重点。由于原有监测技术的瓶颈以及桥梁沉降长期实时监测的困难,研究新型桥梁监测技术,突破原有技术的局限性,具有重要的学术与工程价值。本论文首先介绍了目前桥梁沉降监测意义以及现有监测技术,通过对这些技术的原理、性能及优缺点进行分析,总结了现阶段桥梁沉降监测技术的局限性及其难点,为本论文沉降监测技术的研究提供参考。针对现有桥梁沉降监测技术的局限性,本论文首次提出采用基于多模干涉技术的光纤超声波传感系统用于桥梁沉降非接触式监测,并深入研究了光纤传感器的结构设计与优化、传感系统机理、超声波位移传感系统设计与搭建、传感实验和桥梁沉降模拟测试。主要研究内容包括：(1)系统研究分析了超声波的特性、基于超声波的非接触式测距原理。(2)研究了多模干涉光纤传感器及其对超声波探测机理,理论结合实验对传感器进行结构设计与优化,有效提高了光纤传感器对高频超声波的探测灵敏度。实验研究实现了多模干涉光纤传感器对25kHz以上超声波探测。同时,针对外界环境变化引起传感器信号漂移误差,提出双传感器相位参考技术,通过同步测量与解析参考传感器与测量传感器相位差值,有效降低了由于外界干扰引起的测量误差,大幅提高系统稳定性。(3)理论研究基于超声波的光纤非接触式测距系统机理,设计开发了并搭建非接触式位移传感系统,通过多模干涉光纤传感器对位移所引起连续超声波信号的相位变化进行实时探测解析,研究实现了所设计传感系统对3-7米距离内位移变化的非接触式测量,其位移分辨率达0.2mm。(4)实验室搭建桥梁沉降测试实验系统,模拟桥梁实际沉降发展规律,进行了模拟沉降监测试验,实验实现并验证了所设计传感系统对7米范围内微小沉降变化的非接触式探测,其分辨率保持在0.2mm,测量误差7%左右。通过对桥梁沉降监测的模拟研究实验,验证该传感系统可行性及初步的性能指标,为其用于桥梁沉降监测提供了一定的理论依据和技术支持。
[Abstract]:Bridge settlement will cause structural damage and decrease of bearing capacity, resulting in a series of serious disasters. Therefore, as one of the main parameters to measure bridge health, bridge settlement is the focus of structural monitoring and analysis. Because of the bottleneck of the original monitoring technology and the difficulty of long-term real-time monitoring of bridge settlement, it is of great academic and engineering value to study the new bridge monitoring technology and break through the limitations of the original technology. This paper first introduces the significance of bridge settlement monitoring and the existing monitoring technology. Through the analysis of the principle, performance, advantages and disadvantages of these technologies, the limitations and difficulties of bridge settlement monitoring technology at present are summarized. It provides a reference for the research of settlement monitoring technology in this paper. In view of the limitation of the existing bridge settlement monitoring technology, this paper first puts forward the application of fiber optic ultrasonic sensing system based on multi-mode interferometry to bridge settlement non-contact monitoring, and deeply studies the structure design and optimization of optical fiber sensor. Sensor system mechanism, ultrasonic displacement sensing system design and construction, sensing experiment and bridge settlement simulation test. The main research contents include: (1) the characteristics of ultrasonic wave are studied and analyzed. Based on the principle of non-contact ranging of ultrasonic wave, the multimode interferometric optical fiber sensor and its mechanism of ultrasonic detection are studied. The sensitivity of fiber optic sensor to high frequency ultrasonic detection is improved effectively by designing and optimizing the structure of the sensor based on theory and experiment. The multimode interferometric optical fiber sensor for ultrasonic detection above 25kHz is studied experimentally. At the same time, aiming at the sensor signal drift error caused by the change of external environment, a two-sensor phase reference technique is proposed. The phase difference between the reference sensor and the sensor is measured synchronously and analytically. The measurement error caused by external interference is effectively reduced, and the stability of the system is greatly improved. The theoretical study on the mechanism of fiber optic non-contact ranging system based on ultrasonic wave is carried out, and the non-contact displacement sensing system is designed and built. The phase change of continuous ultrasonic signal caused by displacement is detected and analyzed in real time by multimode interferometric optical fiber sensor, and the non-contact measurement of displacement change within 3-7 meters is studied and realized by the designed sensing system. The displacement resolution reaches 0.2mm. 4) the experimental system of bridge settlement testing is set up in the laboratory, and the actual settlement development law of the bridge is simulated, and the simulated settlement monitoring test is carried out. The experimental results show that the sensor system can detect the small subsidence within 7 meters. The resolution of the sensor system is 0.2mm, and the measurement error is about 7%. The feasibility of the sensor system and the preliminary performance index are verified by the simulation research on bridge settlement monitoring, which provides a theoretical basis and technical support for the bridge settlement monitoring.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U446

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