Abstract:

The occurrence, spacing, filler, cohesive force and other characteristics of the joints of the surrounding rock of a highway tunnel under construction are described in detail on basis of geological sketches and mathematical statistics work, so as to solve the problems in the analysis on the stability of the surrounding rocks in tunnel construction. Then the model of the strata in the tunnel site, which is based on the joint properties, is established by means of threedimensional reconstruction technology. Finally, the potential critical blocks in the free face under nonsupport condition and under support condition are examined by means of block theory, the slip mode and the safety factor are analyzed, and the supporting parameters are optimized. It is concluded that the strength of the designed support is higher than needed and that the safety of the structure can also be guaranteed when the supporting parameters are appropriately optimized. 

Key words: tunnel engineering, block theory, stability of surrounding rock