【作者】 孙曼；

【导师】 刘浩吾；

【作者基本信息】 四川大学 ， 岩土工程， 2005， 博士

【摘要】 大型结构的安全监测,能够及时了解结构性状,防患未然,获得巨大的社会和经济效益。工程结构安全监测的高新技术中,光纤传感具有独特的优势。其中光纤Bragg光栅传感技术灵敏度高,抗干扰能力强,测量稳定可靠,代表着新一代光传感器的发展方向。本文运用光纤Bragg光栅传感技术的特点和优点,解决高土石坝工程集中渗流监测和组合结构损伤检测两项难题,为发展该两领域内光纤光栅监测技术的传感系统和分析方法提供了理论基础和关键技术。本文主要工作和成果如下: (1)首次提出高土石坝集中渗流大范围、定量化监测的光纤Bragg光栅传感技术的科学理念、理论方法和分析手段。首次采用光纤Bragg光栅传感系统,突破了国内外近年来采用DTS分布式光纤测温的局限,实现了光纤传感的选型优化,成为实现高土石坝心墙集中渗流的定位、定渗流量监测的可行途径和新理念。发展了渗流-温度耦合场的有限元分析方法,完成了高土石坝心墙集中渗流的模拟仿真,获得温度分布与渗流通道几何位置和渗流速度及渗流量的关系,用数值手段论证了这一高端技术的可行性。首次为大范围、定量化监测土石坝心墙随机出现的渗流通道位置和渗流量提供了技术途径。(2)提出了地基集中渗漏的光纤Bragg光栅检测方法,发展了流场-温度耦合场的有限元分析方法,得出地基监测孔内流体、温度多场分布,从而确定地基中集中渗流通道位置和渗流量。据此论证了应用该技术监测地基集中渗流的可行性。更多还原

【Abstract】 Health monitoring of large engineering structures is helpful for knowing the behavior of the structures and can then take preventive measurements if some damages occur. Among all the high technologies of health monitoring, optic fiber sensing has its unique advantages. The Fiber Bragg Grating (FBG) sensing, has high sensitivity and stability, strong capacity against disturbance, representing the development direction of new light sensors. This paper uses the advantages of FBG sensing technology to solve two important and difficult problems: detection of seepage flow of high earth-rock dams and damages of composite structures, and the theoretical bases and key technologies for the development of FBG sensing technology in these two fields are provided. There are some creative results in this paper: Firstly,Scientific conception and theoretical, analytical methods of the FBG seepage sensing system for quantification and localization of seepage flow in high earth-rock dams is put forward. Using the FBG sensing system, the limitation of Distribute Temperature System (DTS) used in recent years can be broken free from the optimization of fiber sensor type carried out for the quantification and localization of seepage flow in high earth-rock dams. Finite element method analysis of seepage-temperature coupling fields is presented to solve the numerical analysis problem of the seepage flow in a high earth-rock dam. The distribution of temperature field, seepage field and the relationship between water velocity and FBG temperature are obtained. Secondly, the photo-electric multi-function seepage measurement system is presented. The electrical measurement subsystem and heating subsystem are studied to provide technologies for the seepage flow monitoring in high earth-rock dams and the dam foundations. The heating subsystem is made up mainly of PTC thermistors. It is safe and longstanding. The electrical measurement subsystem is made up of DS18B20 temperature sensors and microprocessor. Tests of a prototype of the system show very good characterization. Thirdly, a new kind method based on FBG sensing technology to measure the interface damages of steel-concrete composite slab of a bridge deck is presented. The FBG sensors suitable for measuring slippages and disengages are presented too. Model tests show that interface damages can be detected by using these FBG sensors and show the rule of damage development. So the mechanism of damages and development process can be discovered. During the composite structure model tests, FBG sensing system experiences three stages:dead loading test, fatigue test (up to 3×106 cycles) and destructive test. The FBG system works properly during the three stages. Abundant data are acquired which are helpful for the discovering of damage rule. Testing results are compared with those detected by strain gauges. The results show that FBG system is very reliable. Lastly, the FBG system management software is developed independently. FBG data can be saved, transfered, printed, processed, displayed using this software. In a word, the FBG sensing high-tech. is develop and combined with the traditional engineering fields. It is quite helpful to develop the technology of safety monitoring of engineering structures, and so has important scientific and practical significance.更多还原