Discussion on Seismic Design of Underground Subway Structure Under the Code for Seismic Design of Urban Rail Transit Structure

The promulgation of the Code for Seismic Design of Urban Rail Transit Structure provides a technical standard for seismic design of rail transit structure in China, good understanding and implementation of the new code is the foundation for the seismic design of underground structure. Through a comparison with the related parameters in civil building construction, the goal and level of seismic fortification, the ground motion parameters and the seismic measures are mainly analyzed. The results show that the seismic design for ordinary subway underground structure can follow the "Two-level, Two-phase" design principle; while the ground motion parameters in seismic design should be selected according to the structural design reference period; seismic grades should be comprehensively determined by structural form, structural height and seismic fortification intensity, on this basis the seismic measures should be adjusted; the effects of adjustment method should be clarified especially for the horseshoe-shaped and circular tunnels built with mine tunneling method; and more detailed measures for seismic structures should be adopted to improve the maneuverability of underground structure seismic measures.