How the response spectrum of non-liquefied loose-to-medium sand deposits is affected by the groundwater level

This study examines the water level influence on the seismic response of sand deposits. The seismic ground response of a sand deposit for two cases was computed: groundwater level near the surface and at great depth. The ratio of soil factors computed for both cases evaluates the influence of having the water table near the surface. This parameter is small when the full range of periods is considered, but rises to ∼1.15 when narrowing the range of periods to 0.2–0.6 s, corresponding to the plateau of Eurocode 8 ground type C response spectrum. So, the water level effect is of the same magnitude of the existing soil factor in seismic codes.