Optimal Site Investigation Through Combined Geological and Property Uncertainties Analysis

Site investigation is crucial in characterizing the geomaterial profile for the design of bridge pile foundations. A site investigation plan should be conducted to maximize geomaterial information and minimize uncertainty. Thus, both geological and property uncertainties should be explicitly incorporated into a site investigation plan. This leads to the question of how to choose the corresponding optimal number and location of boreholes in a multiphase site investigation plan in order to reduce these uncertainties. This study addresses these problems using multinomial categorical prediction and universal kriging on a random field with multiple simulations. Site investigation data for this study are taken from a bridge project in Iowa, USA, which consists of four boreholes, each within the proximity of the pile foundation location. Subsequent numbers of recommended boreholes and their associated locations are determined to minimize the combined uncertainties. The effectiveness of this combined analysis for determining an optimal site investigation plan (OSIP) is validated and compared to an analysis done solely on property uncertainty. The proposed OSIP yields a lower prediction error, improves the prediction of geomaterial type and property, and reduces the subsurface uncertainties. The incorporation of OSIP invariably improves the design efficiency and performance of bridge pile foundations.