Abstract:

The basic understanding of relationship between tunnel excavation and tunnel support is emphasized in terms of follow aspects: 1) Tunnel excavation and support are 2 basic processes of tunnel construction. 2) Minimizing the loosening of surrounding rock is the basic principle for tunnel excavation. 3) Small elastic deformation and plastic deformation are acceptable. 4) Supporting should be carried out when surrounding rock strain deformation is larger than limitation. 5) Supporting first and then excavation scheme should be adopted in unstable surrounding rocks; and excavation first and then support scheme can be adopted in stable surrounding rocks. With the development of tunnel construction technologies, the selection of tunnel excavation method has been changed a lot. The changes include: 1) Large crosssection excavation method is a guide for excavation method selection; and do not just considering the conditions of surrounding rocks. 2) Partial excavation method should not be used as much as possible. 3) Combined excavation method of machinery excavation method and partial excavation method, such as TBM pilot enlarging method, is a normal method in European countries and Japan. 4) The frequent change of excavation method is not feasible economically and safely. The suggested tunnel excavation methods in related criterions in Japan, America and European countries are introduced as follows: 1) In Japan, the tunnel excavation method is determined by surrounding rock classification, tunnel portal and tunnel trunk; full face excavation method and bench method are used mostly; TBM pilot advance enlarging method is used in large crosssection and long tunnel. 2) In America, surrounding rock is divided into rocky surrounding rock and soil surrounding rock； the suggested tunnel excavation methods are full face excavation method, bench method and CD method. 3) Full face excavation method and bench method are the main tunnel excavation methods in European countries due to their good surrounding rock conditions. The fundamental conditions of tunnel excavation method selection, i.e. construction condition, surrounding rock properties, tunnel sectional area, depth of tunnel, construction schedule and surrounding environment, are summarized.

Key words: tunnel, support, excavation method, mining method, full face excavation method, partial excavation method, bench method, machinery excavation method