Abstract: Micangshan extra-long tunnel is the longest highway tunnel under construction in China with the total length of 13.8 km.3D laser scanning technology has the advantages of high-speed and high-precision to obtain the surface of the objects' three-dimensional coordinates.The technology is used to monitoring and analyzing the tunnel's overbreak-shortbreak, thickness of secondary lining,blasting effect of tunnel face,rock's deformation of circumjacent convergence and vault settlement.The results showed that tunnel's overbreak area is accounted for 81%,0～20 cm overbreak area is accounted for 62%,0～10 cm shortbreak area is accounted for 14% in the experimental section;the biggest,smallest and average thickness of secondary lining are 0.662,0.456 and 0.564 m respectively;blasting depth of tunnel face is about 3.048 m and the rock volume is 254.065 m³;maximum circumjacent convergence deformation and vault settlement are 9.5 mm and 5 mm in K54+030 section during 6 days.

Key words: 3D laser scanning technology, Micangshan extra-long tunnel, overbreak-shortbreak, thickness of secondary lining, blasting effect, circumjacent convergence, vault settlement