布里渊光频域分析技术(Brillouin Optical Frequency Domain Analysis,BOFDA)是全分布式光纤感测技术中的一种,具有独特的测试与监测优势.将BOFDA应用于海上超长PHC(Prestressed High Strength Concrete)管桩内力测试,并在超长PHC管桩...布里渊光频域分析技术(Brillouin Optical Frequency Domain Analysis,BOFDA)是全分布式光纤感测技术中的一种,具有独特的测试与监测优势.将BOFDA应用于海上超长PHC(Prestressed High Strength Concrete)管桩内力测试,并在超长PHC管桩成桩过程中,就将传感光缆植入桩身中,可明显提高传感光缆的成活率和测试精度.现场测桩试验结果表明:在超长PHC管桩成桩过程中传感光缆的植入工艺是十分成功的,桩身轴力和侧摩阻力测试结果能够很好地反映桩身内力的分布变化规律,成效显著,为PHC管桩,特别是海上超长PHC管桩的内力测试提供了一种新的内力测试方法,值得推广.展开更多
The method of generating equal-amplitude spectral lines by multi-frequency phase modulation is used in stimulated Brillouin scattering （SBS） suppression. The spectra of three, five, seven, and eleven equalamplitude ...The method of generating equal-amplitude spectral lines by multi-frequency phase modulation is used in stimulated Brillouin scattering （SBS） suppression. The spectra of three, five, seven, and eleven equalamplitude spectral lines are obtained in experiment with flatnesses less than 0.3 dB. Theoretical research on SBS suppression shows that the threshold power after modulation is in reverse proportion to the maximum square of amplitude moduli of fundamental frequency and the nth harmonic wave. The threshold powers of three, five, seven, and eleven equal-amplitude spectral lines are improved by 5.21, 8.36, 9.39, and 10.76 dB, respectively.展开更多
High-sensitivity monitoring solutions are crucial for early warning systems of earth structures. In this paper, we discuss the design and implementation of such systems for natural and engineered slopes using two case...High-sensitivity monitoring solutions are crucial for early warning systems of earth structures. In this paper, we discuss the design and implementation of such systems for natural and engineered slopes using two case studies. At the Gradenbach Observatory, one key element of the monitoring system is a large fiber optic strain rosette embedded in the slope. We demonstrate that the strain rosette can depict landslide deformations much earlier than geodetic sensors like GPS or total stations and is therefore well suitable for an early warning system. In a second application we report the construction of a reinforced earth structure using geogrids. A distributed fiber optic measurement system was installed to measure the current operating grade of the geogrids within the earth structure. About 2 km of Brillouin sensing cables were installed in the project area. It is demonstrated that the developed monitoring system is well suited for assessing the current state of health of reinforced earth structures.展开更多
布里渊光频域分析(Brillouin Optical Frequency Domain Analysis,BOFDA)技术是分布式光纤传感技术的一种。回顾了BOFDA的发展历史,介绍了BOFDA的最新应用进展情况,并提出了基于BOFDA测量桥梁挠度的新方法。通过光纤布设研究提出在桥梁...布里渊光频域分析(Brillouin Optical Frequency Domain Analysis,BOFDA)技术是分布式光纤传感技术的一种。回顾了BOFDA的发展历史,介绍了BOFDA的最新应用进展情况,并提出了基于BOFDA测量桥梁挠度的新方法。通过光纤布设研究提出在桥梁底面采用全面粘贴的方式布设光纤,并分析了光纤应变表征桥梁挠度的理论,最后进行了基于BOFDA的室内桥梁模型测量试验研究。试验结果表明,百分表实测桥梁模型的挠度与桥梁模型上分级集中荷载及模型下表面的光纤应变变化均成正比例关系;BOFDA光纤应变可以标定桥梁模型变形范围,且光纤应变表征的桥梁模型挠度和百分表实测挠度值基本一致。因此,采用BOFDA技术进行桥梁挠度测量是可行的。展开更多
文摘布里渊光频域分析技术(Brillouin Optical Frequency Domain Analysis,BOFDA)是全分布式光纤感测技术中的一种,具有独特的测试与监测优势.将BOFDA应用于海上超长PHC(Prestressed High Strength Concrete)管桩内力测试,并在超长PHC管桩成桩过程中,就将传感光缆植入桩身中,可明显提高传感光缆的成活率和测试精度.现场测桩试验结果表明:在超长PHC管桩成桩过程中传感光缆的植入工艺是十分成功的,桩身轴力和侧摩阻力测试结果能够很好地反映桩身内力的分布变化规律,成效显著,为PHC管桩,特别是海上超长PHC管桩的内力测试提供了一种新的内力测试方法,值得推广.
文摘The method of generating equal-amplitude spectral lines by multi-frequency phase modulation is used in stimulated Brillouin scattering （SBS） suppression. The spectra of three, five, seven, and eleven equalamplitude spectral lines are obtained in experiment with flatnesses less than 0.3 dB. Theoretical research on SBS suppression shows that the threshold power after modulation is in reverse proportion to the maximum square of amplitude moduli of fundamental frequency and the nth harmonic wave. The threshold powers of three, five, seven, and eleven equal-amplitude spectral lines are improved by 5.21, 8.36, 9.39, and 10.76 dB, respectively.
文摘开展围护结构和支撑体系的监测对于控制基坑开挖变形、保证结构安全具有十分重要的意义。传统传感器监测多为点式测量,其自动化程度低、测量值与实际值误差大、难以发挥传感器工程预警的作用。基于布里渊散射光频域分析技术(Brillion Optical Frequency Domain Analysis,BOFDA)的光纤传感器具有空间分辨率高、精度高、信噪比高的优势。通过在4根原有传统钢筋计支撑上布设分布式光纤传感器,文章对布里渊散射光频域分析技术(BOFDA)与传统监测手段进行了对比,分析了支撑体系全断面受力特性,探讨了分布式光纤感测技术在基坑工程监测中的优势。研究结果表明:分布式光纤传感器可反映不同开挖工况下支撑轴力变化规律以及支撑通长方向轴力的不均匀性,实现支撑体系的全断面受力分析以及基坑开挖过程的安全预警。
基金the Austrian Academy of Sciences(OeAW)for funding the landslide monitoring project for several yearsthe Austrian Federal Railways(OBB)for the funding of the geogrid monitoring project,especially the participating departments of OBB-Infrastruktur AG:Tunneling,Surveying and Data Management,Research and Development
文摘High-sensitivity monitoring solutions are crucial for early warning systems of earth structures. In this paper, we discuss the design and implementation of such systems for natural and engineered slopes using two case studies. At the Gradenbach Observatory, one key element of the monitoring system is a large fiber optic strain rosette embedded in the slope. We demonstrate that the strain rosette can depict landslide deformations much earlier than geodetic sensors like GPS or total stations and is therefore well suitable for an early warning system. In a second application we report the construction of a reinforced earth structure using geogrids. A distributed fiber optic measurement system was installed to measure the current operating grade of the geogrids within the earth structure. About 2 km of Brillouin sensing cables were installed in the project area. It is demonstrated that the developed monitoring system is well suited for assessing the current state of health of reinforced earth structures.
文摘布里渊光频域分析(Brillouin Optical Frequency Domain Analysis,BOFDA)技术是分布式光纤传感技术的一种。回顾了BOFDA的发展历史,介绍了BOFDA的最新应用进展情况,并提出了基于BOFDA测量桥梁挠度的新方法。通过光纤布设研究提出在桥梁底面采用全面粘贴的方式布设光纤,并分析了光纤应变表征桥梁挠度的理论,最后进行了基于BOFDA的室内桥梁模型测量试验研究。试验结果表明,百分表实测桥梁模型的挠度与桥梁模型上分级集中荷载及模型下表面的光纤应变变化均成正比例关系;BOFDA光纤应变可以标定桥梁模型变形范围,且光纤应变表征的桥梁模型挠度和百分表实测挠度值基本一致。因此,采用BOFDA技术进行桥梁挠度测量是可行的。
