光纤和砂土界面耦合性能的分布式感测试验研究
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摘要
地质与岩土工程领域中,变形监测一直是评价岩土体稳定性的一个重要指标,其时空演化规律可为工程设计与施工技术参数优化、地质灾害预警阈值设定提供科学的依据。随着光电感测技术的不断发展,其在地质与岩土工程变形监测中的作用越来越重要,然而分布式感测光纤与岩土体之间的耦合性对监测结果有显著影响,阐明两者间的作用机理成为该技术应用的关键环节。文章在综合分析当前地质与岩土工程变形监测技术的基础上,开展了基于BOTDA感测技术的光纤—砂土界面耦合性能拉拔试验,从试验结果和感测光纤特性两方面分析了感测光纤与砂土的耦合性及二者间的应变传递规律。试验结果表明:除第一级拉拔外,数据拟合R2均在0.99以上,显示了光纤实测应变分布具有良好的规律性;由试验数据反算得出的光纤弹性模量约为0.35 GPa,与给定值基本一致;通过感测光纤的F-S端和F-S尾关系,得出光纤—土界面作用过程可分为全耦合、半耦合和相对滑动三个阶段。上述研究结果为分布式感测技术在各类地质与岩土工程变形监测中的应用提供指导,同时为开展各类室内模型试验提供参考依据。
In the field of geology and geotechnical engineering, deformation monitoring has always been an important index to evaluate stability. Its spatio-temporal evolution law can provide important reference for the optimization of design and construction parameters of foundation engineering and the determination of early warning index of geological hazards. With the continuous development of photoelectric sensing technology, its role in deformation monitoring of geological and geotechnical engineering is becoming more and more important. However, the coupling performance between sensing optical fiber and rock-soil body has a significant impact on monitoring results, and clarifying the mechanism between them has become a key part in the application of this technology. Based on the comprehensive analysis of the current deformation monitoring technology of geology and geotechnical engineering, the pull-out test of fiber-sand coupling performance based on distributed sensing technology was carried out. The coupling performance between sensing fiber and sand, and the strain transfer law between them were analyzed from the test results and sensing fiber characteristics.The experimental results show that except for the first stage pull-out, the R2 fitted by the data are all above 0.99, which shows that the measured strain distribution of the optical fiber has better regularity; the elastic modulus of the optical fiber obtained by the back calculation of the experimental data is about 0.35 GPa, which is basically consistent with the given value; by measuring the F-Sheadand F-Stailrelationship of the optical fiber, it is concluded that the interaction process of the optical fiber-sand interface is mainly divided into full-coupling, semi-coupling and relative sliding. The above research results provide guidance for the application of distributed sensing technology in deformation monitoring of various geological and geotechnical engineering, and also provide important reference for carrying out various model tests.
In the field of geology and geotechnical engineering, deformation monitoring has always been an important index to evaluate stability. Its spatio-temporal evolution law can provide important reference for the optimization of design and construction parameters of foundation engineering and the determination of early warning index of geological hazards. With the continuous development of photoelectric sensing technology, its role in deformation monitoring of geological and geotechnical engineering is becoming more and more important. However, the coupling performance between sensing optical fiber and rock-soil body has a significant impact on monitoring results, and clarifying the mechanism between them has become a key part in the application of this technology. Based on the comprehensive analysis of the current deformation monitoring technology of geology and geotechnical engineering, the pull-out test of fiber-sand coupling performance based on distributed sensing technology was carried out. The coupling performance between sensing fiber and sand, and the strain transfer law between them were analyzed from the test results and sensing fiber characteristics.The experimental results show that except for the first stage pull-out, the R2 fitted by the data are all above 0.99, which shows that the measured strain distribution of the optical fiber has better regularity; the elastic modulus of the optical fiber obtained by the back calculation of the experimental data is about 0.35 GPa, which is basically consistent with the given value; by measuring the F-Sheadand F-Stailrelationship of the optical fiber, it is concluded that the interaction process of the optical fiber-sand interface is mainly divided into full-coupling, semi-coupling and relative sliding. The above research results provide guidance for the application of distributed sensing technology in deformation monitoring of various geological and geotechnical engineering, and also provide important reference for carrying out various model tests.
引文
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Iten M.2011.Novel applications of distributed fiber-optic sensing in geotechnical engineering[D].Zurich:Federal Institute of Technology.
Zhang C C,Zhu H H,Shi B,et al.2014.Interfacial characterization of soil-embedded optical fiber for ground deformation measurement[J].Smart Materials&Structures,23(9):095022.
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Zhu H H,Shi B,Yan J F,et al.2015.Investigation of the evolutionary process of a reinforced model slope using a fiber-optic monitoring network[J].Engineering Geology,186:34-43.
程刚,施斌,卢毅,等.2016.一种基坑锚杆(索)分布式检测方法[J].水文地质工程地质,43(4):89-95.
程刚.2016.煤层采动覆岩变形分布式光纤监测关键技术及其应用研究[D].南京:南京大学.
程刚,施斌,张平松,等.2017.采动覆岩变形分布式光纤物理模型试验研究[J].工程地质学报,25(4):926-934.
卢毅,于军,龚绪龙,等.2018.基于BOFDA的地面塌陷变形分布式监测模型试验研究[J].高校地质学报,24(5):778-786.
佘骏宽,朱鸿鹄,张诚成,等.2014.传感光纤-砂土界面力学性质的试验研究[J].工程地质学报,22(5):855-860.
施斌,徐洪钟,张丹,等.2004.BOTDR应变监测技术应用在大型基础工程健康诊断中的可行性研究[J].岩石力学与工程学报,23(3):493-499.
施斌,张丹,朱鸿鹄.2019.地质与岩土工程分布式光纤监测技术[M].北京:科学出版社.
时以亮,倪斌,施斌,等.2015.北京故宫东华门城台分布式光纤监测研究[J].防灾减灾工程学报,35(5):637-643.
涂碧君.2018.基于探地雷达系统的地下管线自动识别技术[D].哈尔滨:哈尔滨工业大学.
王德洋,朱鸿鹄,朱泳,等.2019.薄壁圆环分布式光纤测力传感器的性能[J].激光与光电子学进展,56(10):100602.
王兴,施斌,张丹,等.2015.BOFDA分布式光纤监测技术及其在桩基测试中的应用[J].工程勘察,43(12):13-17.
张慧慧,王茹.2018.基于高分遥感影像匹配的露天矿滑坡形变场监测方法[J].金属矿山,509(11):126-131.
张勤,黄观文,杨成生.2017.地质灾害监测预警中的精密空间对地观测技术[J].测绘学报,46(10):102-109.
郑刚,朱合华,刘新荣,等.2016.基坑工程与地下工程安全及环境影响控制[J].土木工程学报,49(6):1-24.
朱鸿鹄,施斌.2015.地质和岩土工程光电传感监测研究进展及趋势--第五届OSMG国际论坛综述[J].工程地质学报,23(2):352-360.
Li Z,Soga K and Wright P.2015.Long-term performance of cast-iron tunnel cross passage in London clay[J].Tunnelling&Underground Space Technology,50:152-170.
Iten M.2011.Novel applications of distributed fiber-optic sensing in geotechnical engineering[D].Zurich:Federal Institute of Technology.
Zhang C C,Zhu H H,Shi B,et al.2014.Interfacial characterization of soil-embedded optical fiber for ground deformation measurement[J].Smart Materials&Structures,23(9):095022.
Zhang C C,Zhu H H and Shi B.2016.Role of the interface between distributed fibre optic strain sensor and soil in ground deformation measurement[J].Scientific Reports,6:36469.
Zhu H H,Shi B,Yan J F,et al.2015.Investigation of the evolutionary process of a reinforced model slope using a fiber-optic monitoring network[J].Engineering Geology,186:34-43.