A complete set of bearing capacity factor for rectangular footings on clays of undrained shear strength (φ=0) increasing linearly with depth was compiled by combining the exact plasticity solution for continuous footings and the slip circle solution for rectangular footings. Effect of increasing strength with depth was expressed in term of the ratio kB/c
0, where k is the rate of increase in strength with depth, c
0 is the strength at the clay surface and B is footing width. It is examined that the value of kB/c
0 likely to be encountered in practice is within the range from 0.2 to 30.As compared with results of the present analysis, three other kinds of bearing capacity formulae proposed for the case of strength increasing with depth, were found to overestimate the bearing capacity. The maximum extent of overestimation expected in practical problem is almost 300%.A set of approximate expressions for bearing capacity factor was proposed for convenience of practical use, which is function of the ratio kB/c
0 and the footing shape B/L. The maximum extent of underestimation by these approximate expressions is 5%.
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