Abstract:

The project cases, definition and engineering property of huge deformation of surrounding rocks are presented; 3 worldwide commonlyused prediction methods for squeezing deformation of surrounding rocks, i.e., empirical prediction method, semiempirical prediction method and trial testing method, are systematically summarized. The prediction method for the squeezing deformation of surrounding rocks proposed by Hoek in 1999 (semiempirical semitheoretical prediction method) is used to evaluate the stability of the surrounding rocks of F7 fault of ridge section of Wushaoling tunnel, the reliability of the prediction method is assessed and conclusion is drawn as follows: the probability of the deformation prediction failure of supported tunnels is much smaller than that of unsupported tunnels, that is to say, the magnitude of the convergence of the surrounding rocks of unsupported tunnels is more difficult to be controlled. The theoretical analysis on the squeezing deformation of the surrounding rocks of tunnels by means of 3D nonlinear rheology made by the authors, as well as the development of the corresponding software, are presented; and the calculated result is compared with the measured results, which shows that the result calculated according to the 3D mode of the huge deformation is more close to the field conditions than that calculated according to the 2D mode of the small deformation. Finally, a new type of largescale yielding rock bolt/prestressed anchor cable is proposed to control the development of the huge deformation of the surrounding rock of tunnels; the mechanisms and advantages of  the new type of largescale yielding rock bolt/prestressed anchor cable are analyzed, the structures and types thereof are presented, and the concept of future researches are provided; the new type of largescale yielding rock bolt/prestressed anchor cable has been successfully applied in several projects and good economic and technical results have been achieved.

Key words: tunnel, soft surrounding rock, squeezing, huge deformation, prediction, small deformation 2D nonlinear cohesiveelasticplastic constitutive model, hugedeformation 3D elasticcohesiveplastic constitutive model, largescale yielding rock bolt/prestressed anchor cable