Modeling geologic profiles incorporating interlayer and intralayer variabilities

A geologic profile often is composed of multiple material zones due to complex geologic processes. Uncertainties associated with the geologic profile can be categorized into two groups: (1) intralayer variability, which refers to the variation of material properties within the same layer; and (2) interlayer variability, which refers to the uncertainties associated with the interlayer boundaries. The inter- and intralayer spatial variabilities have significant impact on the design and construction of geotechnical structures. This paper proposes an integrated random field model to characterize the inter- and intralayer spatial variabilities of multilayer geologic profiles simultaneously. A transition zone is used to describe the gradual transition of material properties at the interlayer boundary. The proposed model is applied to characterize the spatially variable cone tip resistance at a study site and to evaluate the effects of the integrated spatial variability of undrained shear strength on the reliability of a two-layer soil slope. Both the inter- and intralayer spatial variabilities influence the reliability of the slope. The intralayer variability is relatively more significant for the slope example in this study.