The structure effect of joint network rock mass on seismic response of underground cavern is studied. Based on the discussion of generating principle of two-dimensional joint network

five characterizing parameters

i. e. joint density

joint orientation and its discretization

joint trace length and its discretization

are identified. The powerhouse cavern of Dagangshan Hydropower Station is taken as a study case here. The results indicate that in the precondition of a same seismic level

seismic displacement increases with increasing the joint density. Seismic displacement also increases with the joint inclination increase at the range of 0°-80°. If the discretization of joint inclination is considerable

the seismic displacement is of positive correlation with joint inclination discretization

yet if the discretization of joint inclination is comparatively small

this correlation is ignorable. Seismic displacement increases with increasing the joint trace length increase. At last

little relationship between joint trace length discretization and seismic displacement has been found. Those findings may provide certain reference for the aseismic design of the underground caverns.