Abstract: At present, most researches of reserved deformation of tunnels rely on pointbased analysis of monitoring data. Therefore, it is difficult to obtain the overall change of the tunnel crosssection. In order to solve the limitation that traditional single point monitoring technology cannot meet the adjustment requirement of the reserved tunnel deformation, a method of optimizing the reserved deformation by using 3D laser scanning technology based on the whole crosssection analysis is proposed. The applicable results of the method to Xin′ an No. 1 Tunnel show that the maximum deformation of the test section of 7.5 cm is less than the design reserved deformation of 15 cm. An optimization method is proposed based on quality guarantee rate to set the reserved deformation in a stepped shape. It is finally determined that the reserved deformation of the crown area is 7 cm, and that of other areas is 5 cm.

Key words: tunnel engineering, 3D laser scanning technology, reserved deformation, quality guarantee rate