Soil Dynamic Response and Site Amplification Parameters for Saguenay, Eastern Canada

抄録

Site effect is an important topic in earthquake engineering and seismic risk analyses. It is widely acknowledged that during the vertical propagation of the seismic waves, this phenomenon generally contributes to amplification of the resulting surface ground motion with respect to the local stratigraphy, surface topography, impedance contrast, and the mechanical properties of the surficial sediments This may lead to significant variation of the seismic shaking and structural damage at short distances. The standard procedure in the site-specific seismic hazard analysis is to evaluate the site effects using local amplification factors (AFs) or dynamic site response simulations. The common indicator of the variety of site conditions is the time-averaged shear wave velocity of the en first 30 m (Vs₃₀). However, Vs₃₀ alone may often not be sufficient to adequately assess the site effects and it is often combined with the fundamental vibration period (T_nat). The Saguenay Lac-Saint-Jean region (SLSJ) is characterized with moderate seismic activity and a typical Quaternary stratigraphy consisting of stiff glacial sediments at the base, soft post-glacial Laflamme Sea sediments and more recent alluvial planes. Important impedance contrast exists between the crystalline bedrock and the overlying surficial deposits. In this study, we analyse the site dynamic response through 1D linear and nonlinear simulations using representative soil profiles and earthquake motions. Typical parameters are evaluated to develop amplification functions for the region.