Abstract: Currently there are many tunnels through the slate formation, slate tunnel engineering problems are frequently occur due to the unique nature of slate, and collapse phenomenon is a large part of the engineering problems . The feature and influence factors of slate tunnel are studied by the analyzing the collapse phenomenon of Muzhailing tunnel, then the board stability theory is used in the collapse mechanism of slate, and combine the engineering practice with board stability theory subsequently. Finally, the key methods to prevent collapse phenomenon are showed, and the method is used in the subsequent engineering. The results show that the slate layered characteristics and slowly construction of initial support is the fundamental factors in the collapse occurred, preventing the collapse phenomenon need to study primarily from these two points. The subsequent sections of Muzhailing tunnel are constructed safely; it’s proved that collapse causes of slate tunnel are well analyzed. That is useful to the similar engineering when they want to prevent or deal with the collapse of slate tunnel.

Key words: tunnel, slate, collapse, influence factors, stability of board, preventive method