In-situ properties of Poisson's ratio based on KiK-net seismic observations

Abstract Poisson's ratio has been considered as an important parameter for the analysis of a geotechnical structure under both static and dynamic loads by many researchers. However, most of the studies have been performed using laboratory test such as resonant column and bender element, or the field test without seismic data such as suspension logging, seismic cross-hole and seismic cone penetration, the studies using the geophysical method based on seismic observations are rare. In this study, in-situ properties of Poisson's ratio are investigated based on KiK-net seismic data. The methods for extracting the in-situ Poisson's ratio and describing its variation with shear strain considering effect of groundwater are firstly introduced. Then, an empirical model for the in-situ assessment of small-strain Poisson's ratio is proposed based on the studies of the effects of vertical effective stress, groundwater and rock layer type. Moreover, it is found that the change threshold of the in-situ Poisson's ratio is larger than the laboratory test results. The results of the study are verified in part based on the fact that they are generally consistent with the theoretical and experimental relationships in many ways, and they can be employed as the reference to the engineering practice and related studies, such as site response analysis and specifying material constitutive relationships for the numerical analysis.