Based on the explicit finite element method and 32 CPU parallel computing cluster platform of ABAQUS

considering the heterogeneity of ground soils

a large-scale refined two-dimensional finite element nonlinear analytical model for a multi-geomorphic composite site that consists of alluvial flat，terraces，undulating hilly terrain and monadnock is established in the time domain. The SH wave is taken as the bedrock earthquake motion and nonlinear seismic effect characteristics of the composite site are analyzed. The results show that: (1) the peak ground acceleration(PGA) and peak ground displacement(PGD) of different observation points on the ground surface vary with each other

which is caused by the terrain differences. When it’s under the same input ground motion

the ground surface PGA of alluvial flat area shows obviously larger than that of the first terrace area

however

the PGD of alluvial flat is smaller than that of the first terrace

and the PGD difference is relatively smaller in the alluvial flat area. (2) The horizontal acceleration response spectrum of ground surface appears a double-peak or multi-peak phenomenon

the amplification of ground motion seems outstanding in the frequency band from 0.4 Hz to 1.2 Hz. Moreover

the acceleration response spectrum is related with the input ground motion. (3) The amplification effect and focusing effect of seismic motion are more obvious in specific frequency band(0.5 Hz to 1.75 Hz)

when the frequency is lower than 0.2 Hz or higher than 2 Hz

the seismic amplification characteristics are not apparent. (4) The location of observation point has influence on the acceleration duration，the changing terrain may cause difference of seismic motion duration，besides，the motion duration

in some way

is dependent on the input ground motion characteristics.