Parametric investigation on the effect of sloping topography on horizontal and vertical ground motions

This study investigates the effect of slope site conditions on ground motion amplification based on the seismic response analysis of 3D finite element slope models with different soil types and multidirectional seismic loadings. The numerical results indicate that the amplification ability of the lateral infinite extension slope model on the horizontal x- and y-components of input motion is equivalent and slightly less than that of the vertical component. Then, the effects of several site parameters (soil type, slope height, slope angle and peak acceleration of input motion) on topographic amplification of ground motions are discussed. The ability of topographic amplification decreases with increasing soil's shear wave velocity or peak acceleration of input motion. In addition, the amplification ability does not increase monotonously with increasing slope height or slope angle. Finally, the relationships between the evaluation indices and the distance from the slope crest are discussed. The results show that the maximum topographic amplification factor predominantly occurs near the slope crest within x/H = 1.5, and the correction factor defined in the Chinese seismic code could be insufficient for slope sites with low shear wave velocity soils.