Factor analysis of engineering geophysical sounding data for water-saturation estimation in shallow formations

Abstract

The engineering geophysical sounding method has been applied for in situ investigation of unconsolidated near-surface formations since the 1990s. In this study, we offer an alternative to geophysical inversion methods for data processing. Factor analysis is applied to engineering geophysical sounding and cone penetration test data to extract information on water saturation of the shallow region. A linear correlation is indicated between water saturation and one of the new variables derived by factor analysis. We used a general formula for estimating water saturation and applied it on data measured in 12 shallow boreholes situated over a nuclear waste disposal site. We extended the statistical procedure to estimate the spatial distribution of water (air) saturation between the boreholes. We compared the statistical results to inversion estimations. The study showed that factor analysis gives a quick and reliable solution for the assessment of hydrogeological conditions in shallow prospecting sites.