Seismic Performance of Cohesionless Soil Underneath Gravity Dam

Abstract

Earthquake is one of the worst disasters that any geotechnical designer must keep in their mind during the design steps of any infrastructure. In this paper, seismic performance (i.e., the dynamic response) of foundation (the soil underneath gravity dam) is investigated under sinusoidal wave. Three main shaking table models (1-g) of concrete gravity dam built on a cohesionless soil are tested under 0.7 g sine waveform. The first test contained a concrete dam model which built on dry sand (empty case), the second is constructed in case of fully saturated cohesionless soil (empty also), whereas the last one, the dam is filled with water (i.e., at the upstream). The principles of physical modeling in geotechnics are used in both model construction of the concrete dam and the model preparation. The results of the shaking tests showed that the dynamic response (i.e., the measured acceleration) at different depths and positions for the soil particularly at the upstream side is strongly influenced by the water height at the upstream (i.e., H) with less effect in case of dry soil foundation underneath an empty dam, while it is so clear in case of the saturated foundation for empty dam. The response for the soil underneath the dam model is very safe because of the heavyweight of the dam model, and this was very important finding as this area may contain construction of some significant structural parts such as the blanket of the dam or cutoffs. The pore water pressure governed also during the shaking led to liquefaction under the dam model.