Dynamic soil properties of Hong Kong reclamation sites for seismic applications

Abstract

The paper presents a simplified procedure for estimating key dynamic properties (site period and equivalent damping) of soil reclamation sites in Hong Kong. The methodology has been based on well known theoretical principles and relies only on readily available borehole log data for its implementation. The important influence of the period shifting effect, arising from nonlinear dynamic cyclic response of soils under bedrock ground shaking, is highlighted. An iterative procedure for determining the expected level of soil damping under seismic bedrock ground excitations has also been developed and presented in the paper. A brief review of some bedrock spectral predictions for Hong Kong is then given, followed by a description of a range of Hong Kong reclamation sites of varying locations and depths. These sites have been identified as being suitable for implementing and illustrating the proposed procedures, with the key results being reported in the paper. It is concluded that the proposed method may be used in practice to gain information at a preliminary design stage concerning site properties and the likely effects of site amplification (not covered here) on design-level earthquake ground motions. In this context, the expected ranges of soil equivalent damping ratios have also been evaluated and their significance discussed.