Numerical Study of Inverted Shell Footing Behavior on Sandy Soil

Abstract

Inverted and upright shell foundations, are increasingly utilized in engineering projects as structural elements beneath buildings, towers, curved dams, and other structures. They serve as economical alternatives to shallow foundations when encountering high loads transmitted through weak soil. The purpose of this research is to use the numerical modeling program Midas GTS NX to better understand the load-settlement behavior of inverted shell footings subjected to vertically applied loads. The study involved variables related to the properties of shell cross-sections, embedment depth of footing, and angle of side slope of footing. Also, the shell efficiency factor and the non-dimensional settlement factor for the shell footing are studied. The results show that inverted shell footings exhibit higher load-carrying capacity compared to traditional flat footings. Furthermore, it was found that inverted shell footings within the range of side slope angles of 15°–30° have a higher load-carrying capacity than traditional flat footings. Additionally, an increase in embedment depth was shown to be effective in enhancing the load-carrying capacity of inverted shell footings. From the obtained results, it was also concluded that the shell efficiency factor (η) of inverted shell footings is high. In particular, the inverted pyramid shell footing with an angle of 15°–30° exhibited higher efficiency compared to other footings, by 48.3% and 39.8%, respectively. The settlement improvement factor (F_a) of inverted shell footings was found to be low with the inverted pyramid shell footing at an angle of 15°–30° having a lower value compared to others by 5x10-4 and 507x10-4, respectively.