Abstract:

The significance and targets of pilot tunnels constructed by smalldiameter open TBMs are presented, cases of pilot tunnels constructed by smalldiameter open TBMs abroad are listed, the feasibility to build pilot tunnels by smalldiameter open TBMs is analyzed and factors to be considered in the selection of smalldiameter open TBMs in the construction of pilot tunnels are summarized. Conclusions drawn are as follows: 1) The concept to build pilot tunnels by smalldiameter open TBMs meets the requirements of the state for the infrastructure construction in terms of environment protection and safety; 2) The comprehensive national capability and the construction technologies have reached the relevant requirements; 3) The features of smalldiameter open TBMs should be taken into full consideration and the requirements of rapid boring, geology probing and assistance to the main tunnel construction should be satisfied.

Key words: parallel pilot construction, smalldiameter open TBM, long tunnel with large crosssection, advance pilot tunnel