Model Uncertainty Representation in Geotechnical Reliability Analyses

Abstract

An adequate representation of model uncertainties is important for reliability analyses based on geotechnical analysis models of unknown credibility. A procedure is outlined for calibration of the probability distribution function for the model uncertainty associated with such a geotechnical model. The calibration is based on available field test measurements of quantities, which can be predicted by means of the actual model. The procedure is generally applicable, provided a sufficient amount of field test measurements is available. The procedure is outlined with specific reference to a prediction model for axial pile capacity and a set of pile capacity measurements from field tests on full‐scale piles. An example is presented to demonstrate the applicability of the procedure, based on the American Petroleum Institutes's method for prediction of shear capacities of piles. A first‐order reliability analysis of an example pile is carried out and demonstrates the significant importance of a best‐possible representation of model uncertainty in geotechnical reliability analyses.