load–displacement behavior of semi-deep shell foundations on sand by experimental study

Recently, semi-deep shell foundations have been utilized as an optimum foundation option for a variety of onshore, offshore and land projects due to providing technical and economical advantages. this paper presents an experimental study regarding geotechnical aspects of semi-deep shell foundations. the behavior of physical models having different d/b ratios on the sand with dr = 29, 58, and 73% corresponding to φ =30, 35, and 40° under axial loading have been investigated in 1 g chamber. the impact of shell configuration, foundation geometry and soil characteristics on load–displacement relationship and ultimate bearing load (qu) has been studied. outcomes show different improvement rates in load bearing behavior of skirted hybrid and conical shells according to sand properties and embedment depth. in loose sand, conical shells demonstrate higher bearing capacity, whereas skirted hybrid foundations are more beneficial for substructures on medium and dense sand. comparing the ultimate load of semi-deep shells to that of a circular flat counterpart in different sand states indicates remarkable enhancement of (20–50) % and (50–100) % in foundation performance having d/b = 0.25, and 0.5, respectively. normalized load–displacement relationship (q/qu versus displacement ratio) for skirted hybrid and conical shell foundations on the sand with a relative density of 29% follows a similar trend for different d/b ratios. nevertheless, for shells on the sand with dr = 58 and 73%, an increase in d/b ratio leads to the curves shifting inwards for displacement ratios less than (10–12) % and then outwards for greater proportions. © 2022, iran university of science and technology.