Abstract:
As a typical local irregular topographic, valley can change the seismic properties within the local site, which is usually called the topographic effect. This phenomenon has been confirmed by numerous ground shaking observations and earthquake damage records. However, current knowledge on the site effects of the valley is focused on analytical or numerical methods, and lack of the experimental data from physical models. In this paper, a free-field shaking table model test method considering the valley effect was established, and a series of shaking table test studies on the valley topography effect were carried out. Three sets of circular valley topography with depth-to-width ratios of 1/8, 1/4, and 1/3 were designed for the experiment, and the free-field test under the flat field was used as a reference to compare the topographic effects of the valley site, and the effects of different topographic conditions on the valley effect were investigated. The results show that the valley effect causes the amplification of the ground acceleration response at the local site, and the amplification effect is most significant at the valley top, while the acceleration response within the valley gradually increases from the bottom valley to the valley top. The ground acceleration amplification effect caused by the valley topography is more significant with the increase in incident frequency. The amplification effect of the valley topography gradually increases with the increase of depth-to-width ratio. The research results can provide a scientific basis for the seismic safety analysis of structures around valley topography.