Scale of Fluctuation for Geotechnical Probabilistic Analysis

In the past few years, random field theory has been increasingly used to model the inherent soil variability. The scale of fluctuation is one of the important parameters describing a stationary random field. In this study, the factors affecting an accurate estimation of the scale of fluctuation were studied with numerical experiments to show how a proper sampling strategy can help improve the estimate of scale of fluctuation. Hypothetical data sets were generated from random field theory. Data were then sampled for different sampling strategies. The scale of fluctuation estimated from the sampling programs were compared with the predefined scale of fluctuation. The accuracy with which one can estimate scale of fluctuation depends on both the sampling intensity and extent of the sampling range. For the numerical example in this study, the sampling interval should be close enough such that 10 samples are measured within one scale of fluctuation, and the distance covered by the sampling should cover at least 100 scales of fluctuation.