Investigating small-strain site response using inverse soil dynamic parameters from downhole arrays

Previous research on site response has primarily focused on reproducing and predicting ground motions recorded by vertical seismic arrays. This study evaluated the ability to reproduce and predict small-strain site response at the Treasure Island Downhole Array and Delaney Park Downhole Array using inverse soil dynamic parameters. First, parameters such as seismic wave velocity profiles and Rayleigh damping ratios were obtained through seismic interferometry and spectral ratio methods based on the earthquake records. Subsequently, the validity and reliability of these inverse soil dynamic parameters were evaluated by comparing the simulated and observed ground responses. Finally, the inverse method was compared with other methods considering spatial variability in one-dimensional site response analysis. Quantitative comparisons show that the inverse method effectively predicts and reproduces site response and outperforms the traditional method relying on the single borehole shear wave velocity profile and damping ratio from empirical model. Moreover, the inverse method better captures spatial variability at the Delaney Park Downhole Array.