Abstract: There is little practical experience of asphalt pavement in immersed tunnel in China. As a result, the service status of asphalt pavement of 12 immersed tunnels in China and abroad, such as Hong KongZhuhaiMacao Bridge Subsea Tunnel and Busan Subsea Tunnel in South Korea, etc.[KG-*3], are investigated, and the causes for diseases are analyzed based on literature review, communication and enquiry, onsite observation and onsite test. The results show that: (1) The rut diseases of the asphalt pavement of immersed tunnels are not prominent, the minimum temperature of the road surface is about 6 ℃ higher than that of the natural environment in the project area, the maximum temperature is close to that of the natural environment, and the service temperature usually does not exceed 40 ℃. (2) Cracks are one of the most typical diseases of the asphalt pavement of immersed tunnels, and the segment joints of immersed tunnel are weak links on the asphalt pavement, where crack and damage often occur. (3) In addition, the asphalt pavement of immersed tunnels has other diseases, such as poor roughness, obvious attenuation of skidresistance, and easy formation of pothole diseases at tunnel entrance. (4) For newlybuilt immersed tunnel, mechanical analysis should be carried out according to the tunnel structural conditions, environmental conditions and traffic conditions, and detailed design for the asphalt pavement at segment joints should be carried out further. (5) The SMA with larger NMPS and aggregate with better wearresisting performance are suggested to use for the asphalt material. (6) The asphalt on the upper layer of tunnel entrance should be characterized by good waterresistance.

Key words: immersed tunnel, asphalt pavement, segment, cracks, pothole, skidresistance performance, roughness