Key points are not available for this paper at this time.
Citation: Houlsby, G. T. & Martin, C. M. (2003). 'Undrained bearing capacity factors for conical footings on clay', Géotechnique, 53(5), 513-520. First published by Thomas Telford and available at http://www.geotechnique-ice.com/.
Houlsby et al. (Sun,) studied this question.