Local site effect of soil-rock ground: 1-g shaking table test

摘要

Construction sites are not generally flat but heterogeneous. It would be of significance to explore the patterns of ground response where soil and rock strata laterally distribute near the ground surface. Shaking table test of scaled free-field model is conducted to investigate the local site effect caused by the influence of soil-rock strata. In this test, model ground with artificial soil and rock is designed to reproduce the dynamic characteristics of the prototype. Recorded earthquake waves and site-specific artificial waves are selected as the bedrock motions inputted from the shaking table, in both transverse (SH wave) and longitudinal (SV wave) directions. Four sites of the ground are classified according to the combination of the soil deposit and the rock. The standard spectral ratio (SSR) is introduced to identify the fundamental frequency and the amplification amplitude of the four sites. Correspondingly, one-dimension (1D) theoretical analysis is used to clarify the amplification effects affected by the local constitution at each local site of the ground by comparing the response spectral ratios with the 1D analysis results (Aggravation factor). Site-specific parameters, such as the peak ground acceleration, arias intensity, and acceleration response spectra, are documented with discussions. It is found that the amplifications of locations vary with thickness of soil deposit, nonlinearity of soil property under increasing seismic intensity, and scattering of high-frequency components of input motion.