Laboratory tests are often used to understand dynamic soil behavior and to develop cyclic soil constitutive models. However, the loading paths in lab tests are different from those in the field, resulting in the inaccurate prediction of site response. An increasing number of downhole arrays are available to measure motions at the ground surface and within the soil profile, along with pore pressure response within the soil profile. These downhole array recordings enhance our understanding of the wave propagation through soils. This paper
adapts the SelfSim inverse analysis framework to downhole array data
to extract the nonlinear characteristics of soil material while accounting for porewater pressure generation, and to improve site response modeling. Examples using synthetically generated downhole array data and field array measurements are presented. The paper also presents preliminary analysis
of downhole array measurements from the recent 2011 Japan earthquake.