Numerical evaluation of the effect of soil non-horizontal layering on seismic response of semi-sin alternating hills

Topographic and geological features have a significant impact on ground movements. Some topography is distributed intermittently in nature. Topographic alternation can be one of the reasons for the significant intensification of earth's seismic motion. However, most studies have focused on the amplification caused by a single topography. Limited research has been conducted on intermittent topography. In this paper, the intensification of seismic motion of the earth in heterogeneous semi-sin hills that hill materials, layers with angles of 15 to 75 degrees relative to the horizon, have been investigate. At all angles of layering, with the increase in the number of hills, the displacement intensification also increases, for example, for the ridge, at an angle of 45 degrees, the maximum magnification in the presence of a roughness is 1.63, but the same amount reaches to 1.66 when the three roughness is topographical. At smaller angles, the increase in the amplification of three-layer hills is more noticeable than the two-layer hills, and the larger the inter layer angle, the closer the amplification of the two and three-layer hills to the other. Therefore, each of the parameters of changing the angle of materials of the layers in the hill, as well as the increase in the number of layers in the hill, have an impact on the amount of seismic amplifications and each of these parameters should be considered in seismic designs.