Abstract：The aseismic design of the reservoir faced wholly with asphalt concrete under construction is addressed，which is the largest one in Japan for this type of reservoir. Due to the complex geomorphologic features and geological structures of the site as well as the complicated construction processes of embankments，general response characteristics of the entire reservoir were firstly investigated by 3D dynamic analyses，and then the maximum strains of the asphalt concrete facing for typical cross-sections of the reservoir with potentially great deformation were determined by detailed 2D dynamic analyses. The results show as follows：(1) both acceleration and strain are with a similar distribution character independent on the direction of the seismic excitation，concentrating in the high banking areas of the main dam，the left-side bank，and from the subsidiary dam to the right-side bank；(2) maximum values of acceleration and strain occur in the main dam although they slightly vary with the excitation direction of the seismic motion；(3) a 2D analytical result is slightly greater than that of a 3D analytical result；and (4) maximum strains of the facing for Levels 1 and 2 seismic waves considering the regional factors of this reservoir site are 0.019% and 0.030%，respectively. At the same time，a series of material tests of asphalt concrete mixtures，including mix design and mechanical behavior，are carried out to obtain an appropriate mix proportion. According to the results of numerical analyses and material tests，the seismic safety of the facing was evaluated by using the proposed limit state design method based on the concept of two-level seismic motions and the characteristics of facing structure. The evaluating result indicated that the facing satisfies the safety criterion during Levels 1 and 2 seismic motions at the reservoir site.
