Abstract: The conductive film of cured flexible conductive coating can be used to prepare a sensor system.If such system is attached to the surface concrete or embedded into the interior concrete and deforms with the concrete,the detected resistance change of the system can indicate the real-time cracks and its extension.According to the mechanism of the urban tunnel cracks,this paper proposes the development of low-cost and crack-sensitive conductive coating,which can achieve the early monitoring of large tunnel cracks.Pilot project shows that such kind of coating can ensure the quality,safety,efficiency,and long-term normal operation of the urban tunnel and has great application value.

Key words: tunnel, crack, monitoring, conductive coating, real-time monitoring