Abstract: Vacuum suction type overturning machine is not applicable to the overturning of invert blocks, and the existing method of invert block overturning on the ground is laggard and has many disadvantages. New hydraulic type overturning machine is used in the construction of West Qinling tunnel, which is the first time in China. A set of proved overturning technology is summarized on basis of practice and improvement in the site. Some key points of the new technology are presented. The comparison and contrast between the new method and the existing method show that the new method is superior to the existing one.

Key words: West Qinling tunnel, invert block, vacuum suction type overturning machine, hydraulic type overturning machine, overturning in air, overturning on ground, risk control