Failure envelopes and plastic potentials for eccentrically loaded surface footings on undrained soil

The failure envelope in V-M space for surface foundations on undrained mate rial under eccentric loading can be determined using an extended version of the scaling (or effective area) concept of Meyerhof. A similar displacemen t transformation allows production of the plastic potential. The two-dimens ional finite element analyses of fully attached foundations subject to comb ined vertical (V) and moment (M) loading have been used to calculate approp riate scaling points for deduction of the failure envelope and plastic pote ntial. Failure envelopes and plastic potentials are presented for footings on uniform and non-uniform undrained material and it is seen that the equiv alent 'critical state' or 'parallel point' lies slightly beneath the peak m oment capacity. For accurate prediction of failure envelopes for footings o n non-uniform strength soil, consideration must be made of the apparent red uction of the soil heterogeneity as the area of footing in contact with the soil decreases. Copyright (C) 2001 John Wiley & Sons, Ltd.