Seismic Site Response Analyses of Bay of Campeche Clay Using Predicted Dynamics Soil Properties

Abstract

Abstract Seismic site response analyses are an important first step in the seismic evaluation of fixed offshore platforms in the Bay of Campeche. This analysis is used to estimate ground motions for the development of design response spectra, dynamic stresses, strains, and displacements within the soil profile and liquefaction hazard analyses. Seismic site response analyses of a clayey deposit located in the Bay of Campeche is performed using predicted dynamic soil properties, including the in-situ shear wave velocity based on empirical correlations developed for the Bay of Campeche clay, the shear modulus reduction curves and the material damping ratio curves based on equations also developed for the Bay of Campeche clay. The main objective of the study is to evaluate the effect of using predicted modulus reduction and material damping ratio curves on the design acceleration spectrum at the depth of maximum soil-pile interaction. Site response analyses is also performed using other generic modulus reduction and damping curves presented by Vucetic and Dobry (1991), and Darendeli (2001).The spectral acceleration amplitudes are underestimated when the curves of modulus reduction and material damping ratio of Vucetic and Dobry (1991) and Darendeli (2001) are used in the site response analyses, and overestimated when the curves proposed by Taboada et al., (2017) are used. It is found when comparing the results using laboratory curves that at the depth of maximum soil-pile interaction the maximum ground acceleration and the plateau of the design acceleration spectra are over estimated by 4% when the predicted modulus reduction and damping ratio curves are obtained using the equations developed by Taboada et al., (2017).Therefore, it is important to use predictive equations of modulus reduction and material damping ratio curves developed specifically for the Bay of Campeche clay when dynamic laboratory data is not available to generate these curves.