Abstract: A rare large deformation of strong extrusion fractured surrounding rock occurred to a high-altitude tunnel in the western region of China. To effectively control such deformation, the deformation characteristics of the tunnel and the deformation control effect of different supporting schemes are analyzed, and the construction principle of collapse prevention and deformation control is emphasized. Intensively, the regional structural characteristics, rock mass characteristics, in-situ stress, and surrounding rock loose circle expansion pattern in the entrance section of tunnel are examined, and large deformation mechanism of tunnel in strong extrusion fractured soft rock is analyzed based on mechanical excavation model. Subsequently, a concept of active-passive combined supporting with the core of "sectioned excavation to prevent collapse and arch-bolt-grouting support to control deformation" is proposed, yielding a series of large deformation control technologies of strong extrusion fractured soft rock tunnel. These technologies include sectioned excavation, dense advance support, strengthened steel arch support, built-in prestressed bolt, and expanded radial grouting. The applicable results show that the deformation is reduced by more than 40%, the early deformation rate is reduced by 13.6－20.0 mm/d, and the steel arch stress is reduced by 57%, effectively inhibiting the occurrence of large deformation disasters caused by strong extrusion fractured surrounding rock. 

Key words: large deformation of surrounding rock, strong extrusion fractured surrounding rock, soft rock tunnel, deformation mechanism; active-passive combined support, deformation control technology