Abstract:

 Soft rocks around deep-buried tunnels under high geo-stress conditions are prone to emerging large deformation. Nowadays, the prediction of squeezing deformation is a significant problem during the design and construction of practical engineering. The existing empirical prediction methods of squeezing tunnels are widely used due to its simplicity and convenience, while they also have many limitations, e.g. most of they can only classify the squeezing degree but can’t predict the exact deformation with considering on a few influencing factors, they were developed based on foreign Q system and not applicable for the BQ system of China. Therefore, a new empirical method, that are available for BQ system, is proposed based on more than 100 deformation monitoring data of squeezing tunnels. The method could synthetically take many factors into account, such as tunnel depth, span, ratio of rock strength stress and initial stress, groundwater and structure surface of rock. The proposed method is verified through comparison and analysis of monitoring results of several tunnels with large deformation, and plays a very important guiding role in determining the strength of the support and applying advance reinforcement measures.

Key words: high geo-stress, soft rock tunnel, extruding large deformation, prediction, modified [BQ]