Optimal borehole placement for the design of rectangular shallow foundation systems under undrained soil conditions: A stochastic framework

Abstract

This contribution proposes a framework to identify optimal borehole configurations for the design of shallow foundation systems under undrained soil conditions. To this end, the minimization of a performance measure defined in terms of the bearing capacity standard deviations is considered. The random failure mechanism method is adopted for random bearing capacity evaluation, thereby enabling explicit treatment of soil spatial variability with tractable numerical efforts. A sampling-based optimization scheme is implemented to account for the non-smooth nature of the resulting objective function. The proposed framework provides non-trivial sensitivity information of the chosen performance measure as a byproduct of the solution process. Further, the method allows assessing the effect of increasing the number of soil soundings into bearing capacity standard deviations. Three cases involving different foundation layouts are studied to illustrate the capabilities of the approach. Numerical results suggest that the herein proposed framework can be potentially adopted as a supportive tool to determine optimal soil sounding strategies for the design of a practical class of civil engineering systems.