隧道二次衬砌FBG智能监测与数值模拟

随着公路隧道向长大型方向发展,对其进行长期安全监测是十分重要的工作．光纤布拉格光栅（FBG）传感器作为一种新型的光纤传感器,已被国内外应用于土木工程结构的状态监测和长期监测．在室内进行标定试验,研究FBG的传感特性,得出应变和温度灵敏度系数,证明FBG是一种理想的传感原件,并在某高速公路隧道进行应用．采用三维快速拉格朗日法,获得隧道二次衬砌中应力和位移分布规律,据此提出FBG传感器在隧道内的布设方法、串联粘贴方式及安装工艺;在不同时期对隧道8个断面进行应变监测,并与数值模拟结果对比分析表明,应变与应力和位移具有分布范围的均匀性和分布状态的一致性特点,进一步证明了监测结果的可信性;最后分析应变与降水量随时间的变化特征,评价了隧道的安全状况．     

基于光纤光栅传感技术的桥梁结构应变监测可行性研究

该文阐述了光纤光栅传感技术的基本原理及其优势,介绍了光纤Bragg光栅传感器(FBG)的布设工艺。利用埋入武黄高速公路某大桥内的FBG和电阻应变片实现了该桥梁在荷载试验过程中的应变监测。并通过比较FBG与电阻应变片测得的应变值来验证光纤Bragg光栅(FBG)传感技术用于桥梁应变监测的可行性。     

OFDR光纤传感技术在十字岩柱暗挖法物理模型试验中的应用

 现阶段岩土工程模型试验围岩变形监测多采用点式传感器,仅能获得部分测点的应变,而光纤传感作为一种迅速发展的分布式监测技术,能很好地解决这一问题。对于岩土工程室内试验,现有光纤传感技术无法满足试验对空间分辨精度的高要求。对一种新型光纤传感技术光频域反射技术(OFDR)的测量原理和优点进行介绍,并将其应用于浅埋超大断面圆形隧道十字岩柱开挖模型试验中,对整个模型不同断面进行水平向应变连续监测。根据试验结果,结合有限元分析,表明OFDR能准确记录试验过程中模型内部的应变变化,揭示围岩在十字岩柱开挖方法下的变形规律,反映十字岩柱对围岩的支撑作用,为今后隧道工程开挖提供参考。另外通过算法将应变结果转化为位移结果,并与多点位移计的监测结果进行对比分析,偏差在10%以内。结果表明,该技术可应用于岩土工程试验中的变形监测。     

浅谈FBG在隧道监测中的应用

阐述了FBG传感技术的传感原理及相关参数计算公式,分别介绍了FBG传感技术在钢筋应力,二次衬砌应变、工字钢应变等隧道监测项目及隧道消防中的应用,指出该技术在隧道的安全性监测方面具有广阔的工程应用前景。     

FBG在隧道施工监测中的应用及关键问题探讨

光纤布拉格光栅(FBG)传感技术具有精度高、准分布、实时性、耐腐蚀及抗电磁干扰等独特优势,已在众多工程监测领域中得到应用,但纤细脆弱、交叉敏感的FBG应用到作业环境恶劣和变形规律复杂的隧道工程监测中还有一些关键问题需要解决。探讨了FBG用于在建隧道工程监测中常遇到的封装保护、温度补偿及系统集成问题,提出了相应的解决办法和思路,并以具体工程案例对上述问题进行了分析。研究表明:通过合适的封装和保护可以将埋入式FBG传感器的成活率大幅提高,实现在隧道开挖期间对喷射混凝土的拱架内力、混凝土应变与温度的实时监测。     

光纤Bragg光栅在隧道健康诊断中的应用

介绍了光纤Bragg光栅传感的原理及其应变标定试验情况,并结合其在云南小磨高速公路九龙隧道的左线K6＋130～＋302段的实际应用情况,与钢弦式表面应变仪的测量结果进行了对比分析。结果表明,光纤Bragg光栅应变传感器不仅适用于工程监测,而且在实际应用中具有明显的优越性。     

光纤传感技术在隧道工程中的应用与展望

根据应用对象的不同,从应变传感和温度传感两个角度出发,主要介绍了隧道工程中分布式光纤传感技术和光纤光栅传感技术(FBG)在隧道管片收敛变形、隧道结构纵向沉降或隆起、周边土体位移、围岩变形及稳定性、隧道火灾报警等方面的应用,对具体应用中的光纤布设工艺作了简要介绍。同时讨论光纤传感技术在应用中存在的问题,并展望了该技术在隧道工程上的应用前景。     

光纤技术在地铁隧道健康监测中的应用研究

探讨了隧道监测中光纤光栅传感网络的建立模式,采用光纤技术,监测了深圳地铁某隧道8个危险断面中路面裂缝的位移、墙体应力集中处的应变以及温度等物理量,并结合降雨量调研结果,探究了温度与降雨对隧道健康的影响,指出光纤光栅传感器具有测量精度高、传输距离长、长期稳定的显著优点。     

FBG传感技术在隧道健康监测中的应用

针对隧道传统健康监测的现状及局限性,提出了布拉格光纤光栅(FBG)传感技术,并对该技术在隧道健康监测中的应用方法进行了阐述,指出FBG具有灵敏性高、电绝缘性好、抗老化能力强等优点。     

FBG分布式沉降管在盾构隧道沉降监测中的应用

介绍了一种利用光纤光栅传感技术(FBG)监测地铁盾构隧道沉降的新方法:通过在铝合金测斜管表面特定位置粘贴光纤光栅形成FBG分布式沉降管,并将该种沉降管连续安装在地铁盾构隧道管片的内表面,可以实现对地铁盾构隧道实时分布式远程沉降监测;提出了温度自补偿算法等数据处理方法,解决了分布式沉降数据的处理问题。该技术已在某地铁隧道沉降监测项目得到应用,成功揭示了隧道周围基坑开挖过程中卸荷和降水对地铁盾构隧道竖向变形的影响规律。     

Multi-parameter real-time monitoring scheme for power transmission lines based on FBG sensors

A multi-parameter real-time monitoring scheme for power transmission line is proposed and experimentally demonstrated.The Fiber Bragg Grating(FBG)sensors are used to sensing the information of temperature and strain in the power transmission lines system,and a monitoring center based on client–server model is established to process and display the sensing information.Several FBG-based power transmission line temperature sensors interrogated based on the developed multi-parameter real-time monitoring scheme is experimentally investigated.The result shows that the system is very useful.     

Detecting deformations in uncompacted strata by fiber Bragg grating sensors incorporated into GFRP

Coalfields based in east China, such as Huaibei, Datun, Xuzhou, Yanzhou, Yongxia and Huainan, have suffered paroxysmal shaft lining fracture and repeated deformation after repair in the last three decades. This phenomenon has required the development of fractured shaft lining repairing technology and a method for detecting rock strata settlement. It is proposed in this paper that, with the method of fiber Bragg grating sensor incorporated into GFRP, a sensing network of fiber Bragg grating wavelength division multiplexing (WDM)/spatial division multiplexing (SDM) mixing array composed of 18 fiber gratings is formed, and it is used for monitoring the settlement of uncompacted hydrous strata. It is the first time that the fiber Bragg grating sensing system is embedded into the 180-m deep uncompacted strata, and the field experiments are conducted at No. 3 Jingning Coal Mine. The layout of optical sensors, the fiber Bragg grating detecting system, the drilling of the borehole and the embedding method of fiber Bragg grating sensors are introduced. The monitoring results of fiber Bragg grating sensors are compared with groundwater level monitoring results. Engineering practice shows that the fiber Bragg grating sensors are working normally and they can be used to detect strain safely and stably.     

紧邻基坑的地铁隧道监测技术方案研究

城市深基坑施工会对紧邻环境产生影响,如导致紧邻建(构)筑物产生变形甚至破坏.本文制定了一种新的纵向及横向光纤传感网络的监测方案,对紧邻基坑开挖时既有盾构隧道的受力状态进行了监测.该方案的基础是测量隧道的纵向应变分布,所提出的光纤传感器网络能够将隧道纵向运动解耦分解为剪切和弯曲分量.方案中采用全分布式光纤传感器和光纤光栅...     

松散层沉降光纤光栅监测的应变传递及其工程应用

 为了研究深部厚松散层失水沉降变形特征,建立光纤光栅–胶结层–封装材料及传感器封装材料–钻孔封孔材料–松散层的应变传递计算模型。通过对光纤光栅应变与松散层应变的传递分析,指出前人应变传递理论中所推导的公式不适用于松散层监测的应变计算,由此给出钻孔植入光纤光栅传感器的松散层应变传递计算模型,并分析影响松散层应变传递的因素,指出封孔材料弹性模量在8～15 GPa范围内时可以得到较高应变传递率。针对某矿松散层12个层位安装的24个光纤光栅传感器,采用该模型得出92.40～148.69 m范围内松散层变形沉降的应变监测结果。工程实践表明,该煤矿松散层埋深97.56～104.33,141.94～144.88 m处为最易出现压应力集中的区域,这与煤矿的实际情况、采用相关方法监测的结果基本一致。光纤光栅应变传递理论研究对推动光纤传感技术发展及其工程应用具有重要实践意义。     

土工离心机光纤光栅测试系统及其模型试验研究

光纤光栅传感技术(Fiber Bragg Grating,简称FBG)具有准分布、测量精度高、抗电磁干扰强和实时监测等优点,其传感器可根据监测对象要求小型化。介绍了一套土工离心机光纤光栅测试系统,包括系统的软硬件构成,FBG解调仪,FBG传感器小型化,锚杆、桩基、测斜管以及挡土墙感测模型的制作工艺等。通过一组土工离心机边坡模型试验,验证了该系统应用于土工离心机模型多参量监测的可行性,显示出该系统具有结构简单,测量内容多,测试精度高,量程大,抗电磁干扰强,系统工作稳定,配套光纤光栅传感器重量轻、体积小、可准分布布设、形成整体监测网络等优点,为土工离心机试验监测提供了一种新的手段。     

基于光纤光栅传感技术的隧道健康监测系统

介绍了目前隧道结构健康监测系统的研究现状,探讨了布拉格光纤光栅传感技术在隧道结构监测中的应用,并展望了隧道结构健康监测系统的发展前景,从而进一步推广光纤光栅传感技术在隧道监测中的应用。     

基于光纤光栅传感技术的测量模型土体侧向变形一维分布的方法

开发了一套基于现代光纤光栅传感技术的测试系统和方法,用于测量振动台试验中模型土体内部的侧向变形的一维分布。将分布式光栅传感器黏贴在基底梁上,并植入土体,考虑土体与植入其中的柔性梁共同运动,利用光纤布拉格光栅（FBG）采集植入梁的变形信息,运用连续体力学的方法,计算得到植入梁周围土体的侧向扩展及剪应变沿深度的一维分布。将现代光学传感技术与传统土工试验技术相结合,应用FBG传感器支持单通道多测点,微型轻质及抗电磁干扰等特点,该系统对周围土体扰动小,导线数量也极少,并且信号不受其他传感器电磁信号的干扰。通过一次小型振动台试验,展示了该方法的可操作性,并与加速度记录信号进行对比,验证了方法的适用性。     

Applications of FBG-based sensors to ground stability monitoring

Over the past few decades, many optical fiber sensing techniques have been developed. Among these available sensing methods, optical fiber Bragg grating(FBG) is probably the most popular one. With its unique capabilities, FBG-based geotechnical sensors can be used as a sensor array for distributive(profile) measurements, deployed under water(submersible), for localized high resolution and/or differential measurements. The authors have developed a series of FBG-based transducers that include inclination, linear displacement and gauge/differential pore pressure sensors. Techniques that involve the field deployment of FBG inclination, extension and pore-pressure sensor arrays for automated slope stability and ground subsidence monitoring have been developed. The paper provides a background of FBG and the design concepts behind the FBG-based field monitoring sensors. Cases of field monitoring using the FBG sensor arrays are presented, and their practical implications are discussed.     

Experimental study of a 3D printed geogrid embedded with FBG sensor for reinforcement of subgrade with underlying cave

Road construction in karst areas is a challenging task. Combining the advantages of geosynthetics and fiber Bragg grating (FBG), this paper creatively presents a new type of FBG-3D printed geogrid, which allows reinforcement and accurate deformation monitoring. A series of model tests were carried out to investigate the mechanical and deformation characteristics of the subgrade with underlying karst cave reinforced by FBG-3D printed geogrid. The experimental results indicated that the fully coordinated deformation between FBG sensor and geogrid was successfully achieved by 3D printing technology, and the relationship between fiber wavelength and strain was obtained. The existence of cave had an adverse effect on the subgrade, but the FBG-3D printed geogrids effectively improved the bearing capacity and footing settlement, and the reinforcement effect increased with the decrease of geogrid spacing. In the cyclic loading experiments, the earth pressure inside the subgrade reinforced by geogrid changed as a half-sine wave in each cycle. The FBG sensors accurately measured the strain change inside the subgrade, and the data showed that the deformation of measuring point above the cave model was the largest. The research conclusions provide important basic data for the construction and monitoring of highway and geotechnical engineering projects.