Multistage and combination retaining structures are employed widely in high slopes; but the seismic earth pressure calculation method of this kind of retaining structure is seldom studied. According to the pseudo-static method and the plastic limit analysis theory

the upper bound solutions are derived to calculate the seismic active earth pressure and its coefficient of three-stage retaining structures including gravity retaining wall and two-stage anchored retaining structures based on strength reduction technique. The following factors including horizontal and vertical seismic coefficients

the angle of the retaining wall back

slope surface shape and its multistage retaining structure

soil cohesion

adhesive strength between soil and retaining wall back are taken into account. The case study of two-step anchored retaining structures indicates that static active earth pressure agrees well with the available research; and the effects of the factors such as strength reduction coefficient and axial force of upper anchored retaining structure are significant on seismic active earth pressure of the lower. Sensibility analysis of seismic active earth pressure of gravity retaining wall combined with anchored retaining structure indicates that the sensibilities of horizontal seismic coefficient

height and angle of gravity retaining wall are significant; and the sensibilities of axial force and angle of upper anchored retaining structure are relative small.