Abstract: Dynamic analysis was conducted with FLAC^3D to study the failure mechanism of a two-stage reinforced soil-retaining wall in Wenchuan earthquake. On this basis, the effect of platform width on the seismic performance of the wall was researched. The numerical results reveal that too large horizontal and vertical displacement at the platform is the cause of local failure of the wall. Under seismic action, the maximum horizontal displacement at the top of the wall is in a non-linear relationship with the platform width, and the maximum horizontal displacement of the upper wall firstly decreases with the increase of platform width and then increases; while the horizontal displacement of the lower wall firstly grows with the increase of platform width and then decreases. Vertical displacement of backfill near by the lower wall panel could be reduced by increasing the platform width. Moreover, under low seismic intensity, platform width has no apparent effect on the magnification of PGA (Peak Ground Acceleration) but in the opposite under high intensity. Therefore, the seismic performance of two-stage reinforced soil retaining wall could be improved by designing a reasonable platform width.

Key words: two-stage reinforced soil retaining wall, Wenchuan earthquake, platform width, seismic performance, FLAC^3D