Use of ground based radar to monitor the effect of increased axle loading on rail bridges. Evgeny Shilov. IDS GeoRadar

Use of ground based radar to monitor the effect of increased axle loading on rail bridges aa Evgeny Shilov IDS GeoRadar

Radar technology Radar is the acronym for : RAdio Detection And Ranging an instrument able to detect the presence of object and able to measure the distance between the apparatus and an object. All rights reserved to IDS GeoRadar 3

Radar technology for real time monitoring application The real time monitoring of bridges, buildings, landslides, dams, etc., requires a no-contact technology able to monitor multipoint with high accuracy. The Interferometric Radar Technology is the solution All rights reserved to IDS GeoRadar 4

IBIS-FS application overview IBIS-FS radar technology is currently used for the vibration and displacement measurement The main advantages of the use of IBIS-FS for dynamic analyses is the high accuracy (0,01 mm), the measurement of displacements and the remote sensing nature of the system (up to 1 km) All rights reserved to IDS GeoRadar 5

IBIS-FS product is based on two radar techniques 1. Frequency Modulated - Continuous Wave (FM-CW) technique for obtaining the 1- Dimensional Range Profile with Range Resolution. 17.1 17.3 GHz Single Transmit & Receive Burst All rights reserved to IDS GeoRadar 6

IBIS-FS product is based on two radar techniques 2. The Interferometric Technique computes the displacement of each point/pixels by comparing the phase information of the radar signal collected at different times. First Acquisition t 1 TX RX j 1 d = λ 4π φ 2 φ 1 Second Acquisition t 2 = t 1 + Δt TX RX j 2 l Wave lenght d Displacement measurement with sub-millimetric accuracy All rights reserved to IDS GeoRadar 7

IBIS-FS IBIS-FS Acquisition Mode IBIS-FS measured scenario is determined by Antenna beamwidth (depending on the model, from 10 to 50 ). User s defined maximum range (up to 1.5-2 Km) The measured scenario is divided into range bins, whose number depends on the range resolution (0.5 m minimum, constant with distance). Range resolution Range profile n-th range bin All rights reserved to IDS GeoRadar 8

Radar technology for real time monitoring application The displacement is measured in the direction of the line of sight of the system. To calculate the real displacement is needed to know the acquisition geometry. sin α = h R d = d v sin(α) h α R d α d v We assume only a vertical displacement d los dv R Line of sight displacement Vertical displacement Measurement point distance d v = d R h All rights reserved to IDS GeoRadar 9

Structural monitoring & maintenance for railway bridges The principal aims of the survey were : 1. analyze the status and physical condition of the 12 bridges on the network by comparing the maximum allowed displacement, from engineers who designed and maintain the bridges, with the real measured displacement; 2. verify the possibility to increase the transportable weight per wagon; 3. evaluate the effects of increased train speed on the bridge structure; 4. define a maintenance plan for the whole private railway network, using collected data. All rights reserved to IDS GeoRadar 11

Structural monitoring & maintenance for railway bridges STANDARD EQUIPMENT IBIS-FS SOLUTION Fiber optic deformation sensors Strain gauges positioning Accelerometers All rights reserved to IDS GeoRadar 12

IBIS-FS advantages a) no installation directly on the structure; b) no interruption on the railway traffic before, during and after the measurement activities; c) easy and rapid installation of the measurement set (~20 min); STANDARD EQUIPMENT IBIS-FS All rights reserved to IDS GeoRadar 13

IBIS-FS advantages d) increase the safety for the technicians (no operations on the rail bridge); e) decrease technicians costs (no additional training course and certification required to work on the railway, no additional insurance coverage, less risk); f) multi-point measurement with high accuracy; g) simultaneous displacement and vibration measurements of the structure. All rights reserved to IDS GeoRadar 14

Structural monitoring & maintenance for railway bridges Measurements performed using two IBIS-FS systems Instrument frequency range 17.1-17.3 GHz Range resolution 0.75m Sampling frequency 200hz Total number of train passages recorded: 71 Unloaded: 24 Loaded: 47 All rights reserved to IDS GeoRadar 15

Example survey result Structural monitoring & maintenance for railway bridges IBIS-FS South North Displacement High vibration value 30.02mm (25b) 4mm vibration 35.73mm (24b) 24.58mm (22b) 39.99mm (25a) 3.5mm vibration 40.70mm (19a) 36.17mm (27a) 26.13mm (28a) All rights reserved to IDS GeoRadar 19

Conclusion The survey provided detailed information on vertical deflections, vibration movement and vibration frequencies for multiple positions along each bridge structure surveyed, largely demonstrating the capabilities and accuracy of the system. The data collected have given important information on the possibility to increase the trains load and demonstrate the full applicability of the system into the mining company bridge inspection program. All rights reserved to IDS GeoRadar 24

Summary IBIS-FS sensor provides 1D Resolution 2D Resolution can be obtained with the repetition and the combination of different data acquisition with the radar sensor under movement (SAR / ArcSAR technology)

The overall Interferometric Radar Family in Geosystems application IBIS-FS: SHM Dynamic and Static Monitor. 1D monitoring Hydra-G: SHM / Cutslope / Dam / Tunnel / 3D Structural monitoring Short range / large angular view 2D/3D monitoring IBIS-FL/FM: Landslide / Dam Monitoring Long range 2D monitoring All rights reserved to IDS GeoRadar 30