Application of Distributed Fiber Optic Sensing Technology in the Transportation Engineering Monitoring Bin Shi, Ph.D., China August 5, 2015 ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
The Monitoring Characters of Transportation Engineering Linear and longer Large scale Complicated Geological condition Harsh working environment
Developing tendency of monitoring technology The conventional monitoring technologies have some disadvantages such as point monitoring, difficult to install, poor anti-interference, poor durability and poor stability etc., so they don t meet the monitoring requirements of modern transportation engineering.
In past decades, fiber optic sensing (FOS) technology is rapidly developing, and its monitoring advantages with distributed, long-distance, small size, totally immune to EMC perturbations, long lifetime etc. provide a new way to monitor transportation engineering and other infrastructure engineerings
Fiber Optic Sensor Root Charles Kuen Kao GBM,KBE,FRS, FREng (born 4 November 1933) is a Chinese-born Hong Kong, American and British electrical engineer and physicist who pioneered in the development and use of fiber optics in telecommunications. Kao, known as "Father of Fiber Optic Communications", was jointly awarded the 2009 Nobel Prize in Physics for "groundbreaking achievements concerning the transmission of light in fibers for optical communication".
What is Distributed FOS? Point Quasi-distributed Fully Distributed Point : such as Mechelson and Fibry-Perot sensor Quasi-distributed: FBG (Fiber Bragg Grating ) Fully Distributed: OTDR, ROTDR, BOTDR/A
DFOS based Monitoring Prototype for Infrastructure
DFOS Family Multi-use Fibre Bragg Grating (FBG) DFOS Family Scatter light Optical time domain reflectometry(otdr) Raman OTDR(ROTDR) Brillouin OTDR (BOTDR) Brillouin OTD Analysis(BOTDA) Brillouin Optical frequency domain analysis (BOFDA) 2015-8-10 8 8
DFOS Monitoring System
FBG Product Series FBG Products Fiber grating Grating series FBG Sensors Modulator s Monitoring System FBG Modulators Pressure & osmometer Displace & Stress Temperature Strain & Deformation 迷你土压力计 土压力计 微型渗压计液位计静力水准仪孔压计位移计 锚索测力计钢筋应力计 温度计 ( 工业 ) 温度计 ( 岩土 ) 温度计 ( 电力 ) 表面应变计缆式应变计埋入应变计
Hand FBG Modulator Optical indexes Number of channels 1 Wavelength range (nm) 1525 ~ 1565 Wavelength resolution (pm) 1 Repeatability (pm) 5 Response Frequency 1~5 Dynamic range (db) 40 Channel spectrum Optical interface type Maximum FBG Sensor Capacity per channel 20 Other indexes Display type Can be queried FC/APC Resolution 480*320 Communication interface Power supply Power consumption (W) 5 3.5 inch LCD screen USB Operating temperature( ) -10 ~ 50 Operating humidity Storage temperature( ) -20 ~ 60 Storage humidity Dimensions(length * width * height)( mm) Weight(kg) 1.3 9VDC(With the AC power adapter) 0~80% (no condensation) 0~80% (no condensation) 251*150*43
Portable FBG Modulator Optical indexes Number of channels 2 Wavelength range (nm) 1525 ~ 1565,1510-1590 Wavelength resolution (pm) 1 Scan Frequency(Hz/channel) 2 Dynamic range (db) 50 Channel spectrum Can be queried Power supply 9VDC communication USB,RF,Internet,WiFi Operating temperature( ) -10 ~ 50 Dimensions(mm) 325*275*140 Weight(kg) 4.4
Manufacture of FBG sensors FBG etching Coating Assembling Welding
DSS Product Series DSS Products Modulators Sensing cables Monitoring System Services Surface Interior Point
DSS Modulators (1) BOTDR (EI41,China) item parameter Measure mode Single-end Measure accuracy 45 με Spatial resolution 50 cm Measure max. Distance Max 80 Km Measure time 120-600S OFDR ( Luna,USA ) item Measure mode Max. measure accuracy Spatial resolution Measure distance Measure frequency parameter Single-end 2με 1-5mm Max 100m 5-100HZ
DSS Modulators (2) BOFDA ( FibrisTerre,Germany ) Item parameter Measure mode Double-end Measure accuracy 2 με Spatial resolution 20 cm Measure distance Max 25 Km Measure time 60-300S BOTDA ( Neubrex,Japan ) Item parameter Measure mode Double-end Max. measure accuracy 7.5 με Spatial resolution 5 cm Measure distance Max 25 Km Measure time 60-300S
Manufacture of Sensing Optical Fiber Fiber drawing and coating equipment Bare fiber Fiber extrusion equipment Tight package soft cable
Manufacture and connection of smart GFRP anchor Smart GFRP anchor
Sensing Cables Strain sensing cable Strain & Temp sensing cable
Metal-based S & T sensing belt Porous copper belt fiber Item Parameters Optical fiber type G.652B Cable type metal-based Fiber quantity 2 (S&T) Cable sectional dimensions 15mm*0.15 mm Tensile strength (N) 280 Cable weight (kg/km) 18 Production line Metal-based sensing belt
Installed on the steel-pipe pile Steel-pipe pile Point welding Glued by epoxy End protection
Steel-strand sensing cable Item Optical fiber type Cable type Fiber quantity 1 Cable sectional dimensions Parameters G.652B metal-based Φ5 Tensile strength (N) 930 Cable weight (kg/km) 38 Steel-strand twisted and weaved equipment Steel-strand sensing cable
Installed in the cast-in-place pile Strapping End protection Grouting Pile forming
Steel-strand sensing cable Implanted in borehole weight dropped into borehole grouting protection
Soft tight-packed strain sensing cable Item Parameters Optical fiber type G.652B Cable type HY Fiber quantity 1 Cable sectional dimensions Φ 0.9-2.0 Tensile strength (N) 25-38 Cable weight (kg/km) 3-8 Implanted into PHC Pile grooving Embedded in Epoxy seal End protection
Point fixed strain sensing cable Implanted into soil Item Parameters Optical fiber type G.652B Cable type point to point Fiber quantity 1 Cable sectional dimensions Φ 4.5-8.0 Tensile strength (N) 120 Step length (m) 1-20 trenching point fixation laying the fiber covering
DTS Product Series DTS Products Modulator Sensing cable Monitoring System Service ROTDR ROFDR 金属基装温度传感光缆 金属基装温度传感光缆 单层钢丝加强中心管束感温光缆 高强度铠装测温光缆 钢丝编织网铠装光缆 塑封芳纶夹钢丝编织管铠装光缆 无缝管铠装感温光缆 钢丝加强铠装光缆 中心管束式温度传感光缆 扁平型纤维加强温度传感光缆
Carbon fibre heatable temperature sensing cable Item Parameters Optical fiber type MM Cable type heatable Fiber quantity 1-3 Cable sectional dimensions Φ 3-8 Tensile strength (N) 350 Heating power(w/m) 6-20
Case one: Xuanwu-lake tunnel FOS monitoring
Project scheme Selection of the optical fiber Based on many experiments, the jacketed SM optical fiber from Corning Co Ltd is selected as sensor. Specification: 8.3/125/900/ m (core/cladding/protective coating); Weight: 0.9 kg/km; Maximal tension: 6.6 N; Minimum bending radius: 3.0 cm Compressive strength: 200 N/m; Working temperature: -20~+80 C; Working wavelength: 1.3~1.5 m; Refractive index error: 0.36%;
Installation of BOTDR sensing fibers FOS sensing fibers were installed on the surface of the concrete wall and arch with three configurations: (1)Overall Adhesion Method (OAM) (2)Fixed-point Adhesion Method (FAM) (3) -shaped Fixed-point Adhesion Method ( -FAM)
The Layout of Optical Fiber Installation Fiber cable
The installation profile of Sensing fibers Southern tunnel Southern tunnel Location of sensing fiber Groove size 2015-8-10 36
Tridimensional layout of sensing fibers installation on the arch
Deformation distribution of expansion and contraction joint along the Tunnel (1) Position No. Position ( from South Entrance) m Maximum (mm) Minimum (mm) SP 13 450 0.139-0.022 SP 15 405 0.128-0.025 SP 17 355(near center) 0.094-0.021 SP 21 256 0.103-0.004 SP 23 190 0.135-0.015 SP 25 38 0.127-0.008 SP 27 114 0.142-0.007 2015-8-10 40
{ 应变 /% Deformation distribution of expansion and contraction joint along the Tunnel (2) 0.6 expansion 温度伸缩缝 and contraction joint 传感光纤末端 Sensing fiber end 0.4 0.2 0.0-0.2 Concrete 混凝土衬砌 section From 自 2003 30/9/2013 年 9 月 30 to 日至 3/11/2013 2003 年 11 月 3 日 600 800 1000 1200 1400 1600 1800 Distance/m 距离 2015-8-10 41
strain temperature 气温 ( ) 40 应变 ( ) 800 600 400 200 0-200 -400 temperature 气温 30 20 10 0 525 595 626 735 830 920 1040 1130 1250 1370 1460 1550 1640 1730 2003-5-22 2003-6-23 2003-7-21 2003-8-26 2003-9-30 2003-10-21 日期 date 2003-11-17 2003-12-18 2004-1-16 2004-2-22 S4 线典型点有效应变变化 Negative correlation between temperatures and strain values of Line S4 2015-8-10 42
Abnormal values monitored by BOTDR at 90m 1000 800 异常 Abnormal value 545-635m 段应变 section 异常 Abnormal value 600 400 200 0 2003-4-25 2003-5-12 2003-6-2 2003-7-7 2003-7-30-200 540 560 580 600 620 640 2015-8-10 43
Case two: Application into the pavement monitoring
100 strain Some of test results (1) Cracking area 80 60 extension compress ion 应变 ( ) 40 20 0-20 -40 distance 0 小时 31 小时 55 小时 80 小时 104 小时 -60-80 -100-120 0 2 4 6 8 distance 距离 (m) The surface strain distribution after grouting 104hrs
strain Some of test results (2) 应变 ( ) 100 80 60 40 20 0-20 -40-60 -80-100 -120 0 小时 31 小时 55 小时 80 小时 104 小时 0 2 4 6 8 distance 距离 (m) The strain distribution of interior steel rebar S9 after grouting 104hrs
Application of Raman OTDR(ROTDR) 电力系统 建筑系统 海洋开发 化工系统
Raman OTDR(ROTDR) 高速公路地基温度监测系统 The DTS of the pavement of highway
Raman OTDR(ROTDR) 高速公路路面结冰监测系统 The DTS of the road surface freezing of highway
Conclusion DFOS, as an innovative sensing technology, is very useful and powerful to monitoring transportation engineering. However, some of further R & D work need to do, such as: low-cost demodulator; special sensing cable for measurement of large deformation; improvement of manufacture and installation technology; software to deal with huge data, and code making etc. However we do believe that DFOS will have a huge application in the infrastructure monitoring including transportation and geo-engineering.
International Forums on Opto-electronic Sensor-based Monitoring in Geo-engineering (OSMG) In 2005,under the support of National Natural Science Foundation of China, our team set up International Forums on Opto-electronic Sensor-based Monitoring in Geo-engineering (OSMG) in. Now five Forums have been successfully held in 2005, 2007, 2010, 2012, 20014 respectively.
Acknowledgment It is grateful that the project is supported by National Basic Research Program of China(973 Program)(NO. 2011CB710605) National Key Project of Scientific and Technical Supporting Programs Funded by Ministry of Science and Technology of China (NO. 2012BAK10B05), The State Key Program of National Natural Science of China (Grant No. 41230636 )