Investigating the Effects of Thickness, Depth, and the Number of Weak Soil Layers on Seismic Site Response

Document Type : Research Paper

Authors

1 Faculty of Civil Engineering, Sahand University of Technology, Tabriz, Iran

2 Faculty of Civil Engineering, Sahand university of Technology, Tabriz, Iran

Abstract

Site conditions, including the shape and depth of the layers, their location, and the area's topography, affect the seismic site response, which can influence the performance of transportation infrastructure. This study investigates the effect of a weak layer, including soft clay and loose sandy soil, on the seismic site response using DEEPSOIL software through nonlinear time-domain analysis. The Tabas earthquake record (Mw=7.4) was selected for site response analysis in this study. The effects of various parameters, such as the thickness of the weak layer, its location at different depths, and the number of layers, were considered. The results showed that in the case of a weak clay layer with a thickness of 3 meters and a weak sand layer with a thickness of 5 meters at the surface, the maximum acceleration increases significantly. As the thickness of the shallow weak layer increases, the seismic response decreases, and the maximum acceleration occurs at longer periods. A comparison of acceleration spectra for different weak layer positions showed that the presence of a weak layer near the ground surface and at a lower depth has the greatest effect on the acceleration spectrum, increasing the maximum acceleration. Although the multiplicity of weak layers reduces the maximum acceleration, the acceleration spectrum exhibits successive peaks at different periods, particularly in loose sandy soils.

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History

  • Receive Date: 10 February 2025
  • Revise Date: 26 February 2025
  • Accept Date: 15 March 2025

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