Effect of Fuzzy Boundaries on the Bearing Capacity of Footings on Two-Layered Clay

In this study, fuzzy logic was implemented to formulate the fuzziness of layer boundaries for a two-layered clay soil. A field of two-layered clay with fuzzy boundaries between layers was generated, and then the bearing capacity of strip footing on this field was calculated by the assumption of plane-strain conditions. The Mohr-Coulomb failure criterion was used and bearing capacity calculations were based on finite difference method. The effect of fuzziness in layer boundaries was investigated for the case of strong-over-weak clay. It is concluded that the analyses by applying fuzzy boundaries yielded more conservative results than classical two-layered bearing capacity calculations when the ratio of thickness of upper layer to the width of footing exceeds 1.  When the ratio of thickness of upper layer to the width of footing is lower than 1, the bearing capacity of footing on two-layered clay is higher by considering fuzzy boundaries.