Undrained Vertical Bearing Capacity Factors for Ring Shallow Footings

Abstract

In this paper, numerical computations using FLAC code are carried out to evaluate the effects of both the ratio of internal radius to external radius ‘r i /r o ’ of the ring footing and the embedment ratios up to unity on the undrained bearing capacity factor ‘ $$N_{c}^{\prime }$$ ’ for different roughness conditions. It is observed that for both smooth and rough surface ring footings, hardly any reduction occurs in the value of $$N_{c}^{\prime }$$ with an increase in the ratio r i /r o up to 0.25. Whereas for r i /r o > 0.25, the values of $$N_{c}^{\prime }$$ decrease significantly with increasing r i /r o . However, for embedded ring footing with rough sides, the results indicate that the bearing capacity difference between circular and ring footings decreases with increase of the embedment depth. For instance, for r i /r o = 0.5, the difference vanishes completely for embedment ratio >0.5. The results from the analysis compare reasonably well with available theoretical data from the literature.