Abstract: During the construction period of unsupported hole of tunnel project，it is an essential factor for the security support，reasonable construction and safe use of the hole to accurately judge the surrounding rock grade in time. In this paper，taking a project under construction as a case，the comprehensive judgment on the surrounding rock grade is made by four means as the empirical judgment，“standard” calculation，Barton computing method and the advance geological forecast. This provides a basis for timely adjusting the support design and the construction program.

Key words: Tunnel engineering, Surrounding rock grade, Barton method, Advance geological forecast