Reliability-based robust geotechnical design of spread foundations considering multiple failure modes

Abstract

This paper presents an update for the reliability-based robust geotechnical design (RGD) method in the design of a soil-foundation system by systematically considering four different potential failure modes including: bearing resistance failure of subsoil, excessive foundation settlement, punching and bending failure of the spread foundation. Given the uncertainties in the critical geotechnical and structural parameters, a comprehensive investigation of the reliability and robustness of the soil-foundation system considering both single failure mode and multiple failure modes were conducted in this study. Moreover, the optimal designs of the soil-foundation system with respect to robustness and cost efficiency are found on the premise of satisfying the safety requirements. The results from this study indicate that both the uncertainties of the geotechnical and structural parameters should be taken into account in the RGD of soil-foundation system considering multiple failure modes. Without properly accounting for the width-to-height ratio of the foundation, increase of the footing geometries and the construction cost will not always lead to a safer and robust design. Besides, bearing resistance failure of subsoil has most significant influence on the reliability and robustness of the soil-foundation system and is identified as the control failure mode.