Undrained horizontal-moment bearing capacity of caisson foundations in over-consolidated clay considering effects of gap

Abstract

When a caisson foundation moves laterally, a gap between the rear side of caisson and the soil is more easily formed in over-consolidated clay. The undrained horizontal-moment bearing capacity of a caisson foundation in over-consolidated clay was investigated through 3 D finite element analyses. To investigate the effects of aspect ratio, caisson size, surface soil strength, and soil strength distribution on gap formation, a parametric study was conducted for L/D ratios varying from 0.5 to 3, diameters varying from 4 m to 12 m, lengths varying from 6 m to 24 m,sum varying from 2 kPa to 20 kPa and k varying from 0 to 1.5 kPa/m. The results show that the failure mode of caisson foundation under lateral load and moment in over-consolidated clay changes due to the formation of a gap. The gap has a significant impact on the undrained bearing capacity of caisson foundations, and with the decrease of caisson size or the increase of surface soil strength, the gap has a greater impact on the bearing capacity. Based on the research, a gap-influence coefficient and horizontal-moment composite bearing capacity has been summarized to provide reference for the design of caisson foundation in over-consolidated clay.