Quantifying the anisotropic electrical resistivity of marine clays: A comprehensive model integrating index properties, gradation, and aging effects

Abstract

Archie's cementation exponent (m) is a critical parameter for the resistivity-based characterization of marine sediments, as it enables the accurate estimation of porosity or void ratio profiles essential for offshore foundation design. However, its quantification remains challenging due to the complex anisotropic fabric of natural clays. This study investigated directional electrical behavior by combining laboratory experiments, ridge regression modeling, and field validation. Results on representative commercial clays (three kaolins and four bentonites) demonstrate that m is primarily governed by intrinsic index properties, with a log-linear model achieving high predictive accuracy (RMAE <7%). Validation using seabed clays from South Korea revealed that intrinsic properties alone are insufficient for natural deposits. This study identified that particle size distribution significantly enhances pore-path complexity; thus, incorporating gradation-related parameters in the model reduced the RMAE for remolded field samples to 8.6%. Furthermore, a time-dependent aging correction factor was introduced to account for long-term fabric development, reducing RMAE for undisturbed specimens from 40.7% to 18.6%. Finally, this study established that electrical anisotropy (λe) is a robust geophysical metric for assessing sample disturbance, with λe ranging 1.22-1.34 identified for boundary between intact and disturbed fabric. This framework supports reliable resistivity-based characterization for critical offshore infrastructure design