Depth factors for ring foundations in cohesive soil using numerical analysis.

Abstract

Shallow foundations are seldom rested on the ground surface and are often embedded below the surface. The undrained bearing capacity of embedded footings and the depth factors associated with it for circular and strip foundations were extensively studied in the past. However, the effect of embedment on the undrained bearing capacity of ring foundations has not received much attention. In this paper, the results of numerical analysis to study the effect of embedment of ring foundations resting on cohesive soil are presented. The influence of variation in the geometry of the ring foundation, the footing side roughness coefficients, and the increasing shear strength of cohesive soil has also been studied. The results show a variation in the depth factors by varying the inner and outer diameter of the ring foundation, footing side roughness coefficient, embedment depth, and increasing shear strength of the soil. Based on the results of the analysis, the authors have proposed an equation to evaluate the depth factors for embedded ring foundations in cohesive soil. The failure pattern of subsoil has also been presented and discussed. The depth factors obtained from this study can be used by practicing engineers to evaluate the bearing capacity of onshore and offshore ring foundations in cohesive soils.