Abstract: Large deformation is a key problem in tunnel engineering. In this paper, the definition, classification and mechanism, judgment criteria, control theory and measures for large deformation of surrounding rock in China and abroad are analyzed and summarized. Meanwhile, the control philosophy of large squeezing deformation is introduced, and suggestion that full play should be paid to the role of the support system in improving the loadbearing capacity of the surrounding rock as much as possible rather than passive loadbearing is put forward. Furthermore, the key research trend and breakthrough point of the large squeezing deformation are discussed, and the highstrength prestressed primary (type) support system and its components and key points are proposed by emphasizing its core importance in the support system. Finally, it is verified by means of field test that the proposed highstrength prestressed primary (type) support system can better control the displacement of the large deformation surrounding rock and shorten the time for the deformation to become stable. The research results can provide a feasible new concept and support technology system for the contorl of the large deformation of tunnels of the same type.

Key words: tunnel, surrounding rock large deformation, support theory, support system, prestressed anchor