Investigating the Site Response Variability of Deep Sedimentary Column Induced by Varying Soil Friction Angles

Abstract

Ensuring the danger level for sustainable development requires a proper ground response analysis with reliable geological properties of deep sediment deposits up to bedrock. The seismic assessment procedure commonly dealth with the upper 30 meters of soil, overlooking the influence of deeper sediment layers. This study performs the seismic response of an entire soil column extending to bedrock, accounting for the soil frictional angle variability. A one-dimensional nonlinear ground response analysis was conducted using 28 earthquake records, with soil friction angles ranging from 10 to 60 degrees. The results highlight the nonlinear behavior of soils, particularly the modification of shear modulus and damping ratio with depth, influenced by changes in frictional angle and effective vertical stress. It indicates that the 10° frictional angles produce a minimum spectral acceleration demand, primarily due to the high energy dissipation in the over-softened upper layer, hence, reduction in peak ground acceleration (PGA). While a 30° friction angle produces high spectral acceleration at short period in shallow depth. The seismic response resulted in a 0.54 times decrease in peak acceleration in the ground relative to bedrock, highlighting the significance of deep soil investigation. This study shows that different friction angles present a greater understanding of seismic site response, leading to better hazard assessment insights.