The fifth China-Japan Joint Seminar for the Graduate Students in Civil Engineering

1. The fifth China-Japan Joint Seminar for the Graduate Students in Civil Engineering AN OVERVIEW ON THE TECHNOLOGY OF HIGH SPEED AND NON-DESTRUCTIVE INSPECTION OF HIGHWAY TUNNEL LINING DEFECTS H. Liu, X. R. Liu & X. Y. Xie Geotechnical Department of Tongji University, Shanghai, China

2. OUTLINE 1 Introduction & Requirements 2 Existing TechniquesExamined 3 Methods Suitable forthe Topic Conclusions & Outlook 4

3. 1 INTRODUCTION & REQUIREMENTS

4. 1 Introduction Mountain highway tunnels suffer from great external rock pressure, seismic load, and concrete deterioration. Furthermore, differing from on-ground structures, their design conditions vary case by case. So it is common to find deformation, severe leakage, big cavities, cracks and other lining defects after the tunnels are put into usage. Mountain Highway Tunnel Rock pressure Seismic load Concrete deterioration Varying design condition Cavities Deformation Leakage Cracks

5. 1 Introduction

6. 1 Introduction How to detect all these lining defects Manual methods geophysical surveys Slow fast destructive Non-destructive imprecise accurate What are requirements

7. 1 Requirements The aim of non-destructive testing methods is to obtain complete, reliable and reproducible data on the state of the entire highway tunnel lining. Requirements Essentially non-destructive Examination at any point 1 2 Used in different tunnels Not be influenced by installations 3 4 High traveling speed Resistant to vibrations and operate in different climate 5 6 Established accurate defective zones Results should be available immediately 7 8

8. 2 Existing Techniques Examined

9. 2 ExistingTechniques Examined Mechanical Oscillation Techniques 1 Microseismics and sonic emission analysis Structural dynamic methods Measuring the response to an artificially induced vibration Seismic reflection and refraction Ultrasonics--reflection and indirect surface transmission Radiation Techniques 2 gamma ray backscatter neutron backscatter determine the density and moisture content

10. 2 ExistingTechniques Examined 3 Electric and Electronic Techniques eddy current methods ground penetrating radar electrical potential methods 4 Optical Techniques infrared thermograph Multi-spectral analysis CCD digital camera

11. 2 ExistingTechniques Examined Discussion Advantages and disadvantages of various techniques

12. 2 ExistingTechniques Examined Advantages and disadvantages of various techniques Georadar Infrared thermography CCD digital cameral

13. 3 Methods Suitable forthe Topic

14. 3 Methods Suitable forthe Topic Ground penetrating radar (GPR) CCD digital camera Infrared topography

15. 3 Methods Suitable forthe Topic GPR Operating principle: used in reflection mode. high-frequency electromagnetic wave interfaces the reinforcing steel bar defects in the lining emitting antenna receiving antenna GPR has been popularly used to detect the tunnel lining, and it can detect the crack, leakage and cavitiesbehind the lining.

16. 3 Methods Suitable forthe Topic CCD Camera CCD Camera is widely used for the inspection of structural surfaces, especially the crack detection of tunnel lining. Operating principle: Image acquisition system Power supply Illuminator Tunnel Optical device CCD Camera Image processing system Data storage Image analysis system Crack map Information of crack

17. 3 Methods Suitable forthe Topic Infrared topography Operating principle: Infrared topography makes use of thermal radiation, which is radiated by every surface. A thermal flow can be created through a current of gaseous material or a liquid material. Points affected by such thermal flows are generally characterized by a pronounced increase or decrease in temperature, in comparison with their surroundings. In this way, possible damage in the tunnel lining can be determined through the use of infrared topography. moist patches water seepage mainly Identify

18. 4 Conclusions & Outlook

19. 4 Conclusions & Outlook GPR Cracks and cavities behind the lining CCD camera Defects (crack) on the surface of the lining Infrared topography moist patches water seepage integrated inspection car

20. Thank you!