Slip Line Analysis

Bearing capacity of circular foundations on clay

The purpose of this project is to present a series of upper bound solutions for circular foundations on an incompressible clay with a Tresca yield condition. We begin with solutions for a flat footing at the soil surface, for which there are well-known solutions, which are widely regarded as “exact” (to within numerical roundoff): Nc=5.94 for a smooth footing and 6.05 for a rough one. We extend these solutions to problems involving conical foundations, strength increasing with depth, and foundations below the ground surface. For these cases, we compare principally with lower bound solutions published by Houlsby and Martin (2003), and we address the discrepancies between the solutions.

References:

  • Houlsby, G. T. (1982) ‘Theoretical analysis of the fall cone test’, Geotechnique. Thomas Telford Ltd, 32(2), pp. 111–118.
  • Houlsby, G. T. (1983) ‘Calculation of stresses on shallow penetrometers and footings’, in Proc. IUTAM and IUGG Symp. on Seabed Mechanics, pp. 106–112.
  • Houlsby, G. T. and Martin, C. M. (2003) ‘Undrained bearing capacity factors for conical footings on clay’, Géotechnique. Thomas Telford Ltd, 53(5), pp. 513–520.
  • Osman, A. S. and Bolton, M. D. (2005) ‘Simple plasticity-based prediction of the undrained settlement of shallow circular foundations on clay.’, Géotechnique. Thomas Telford, 55(6), pp. 435–447.
  • Osman, A. S. and Bolton, M. D. (2005) ‘Simple plasticity-based prediction of the undrained settlement of shallow circular foundations on clay’, Géotechnique, 55(6), pp. 435–447. doi: 10.1680/geot.2005.55.6.435.
  • Skempton, A. W. (1951) ‘The bearing capacity of clays’, in Proc. of Building Research Congress. ICE, pp. 180–189.
  • Vesic, A. S. (1975) ‘Bearing capacity of shallow foundations, Foundation engineering handbook.