This specification is formulated to standardize the design of hydraulic tunnels and ensure the design quality with the view of making use of the state-of-the-art technology， meeting the requirements for safety， applicability， cost-effectiveness， and rationality.

This specification is applicable to the design of Class 1， Class 2 and Class 3 hydraulic tunnels in water resources and hydropower projects， but not applicable to the design of hydraulic tunnels with steel linings in rock/soil mass.