Application of New Austrian Tunneling Method in excavation of large-diameter tunnels

As for the large cross-section tunnel excavation and complicated geological conditions,in the construction of discharge tunnel in the right bank of Xiluodu Hydropower Station,great importance shall be attached to the relationships between excavation and support,otherwise,collapse and roof fall may happen.We mainly present the construction schemes prepared based on the construction principles of New Austrian Tunneling Method(NATM),taking full consideration of the safety and stability of surrounding rock in construction period from stratified excavation and support form,standardizing the construction procedures,making the supporting construction following the excavation to the greatest extend.As a result,the dynamic,random and changeable transformation process of excavation and support is transferred into relatively fixed construction procedures.