New method for estimation of the scale of fluctuation of geotechnical properties in natural deposits



One of the main distinctions between geomaterials and other engineering materials is the spatial variation of their properties in different directions. This characteristic of geomaterials -so called heterogeneity- is studied herewith. Several spatial distributions are introduced to describe probabilistic variation of geotechnical properties of soils. Among all, the absolute normal distribution was adopted as appropriate distribution which best represents these properties in the horizontal direction.
Variation of geotechnical parameters in the vertical direction is however conceived to follow a deterministic trend. With the aid of random field theory and local average subdivisions (LAS) formulation and using MATLAB Mathworks, virtual data with different correlations were produced and by employing the autocorrelation function, a trend for this function was invoked for different predetermined values of scales of fluctuation. It was found that the autocorrelation function has a deterministic trend as long as the scale of fluctuation is not exceeded. It is concluded that for distances further than the specified scale of fluctuation the behavior is chaotic and this can be an index to calculate the scale of fluctuation of the experimental data.