Study the behavior of square footing in clayey soil subjected to vertical loading

Abstract

Foundation is a part of the structure that transmits the load applied from the super structure to the soil below. Estimation of the bearing capacity of foundation is one of the most complicated problems in geotechnical engineering, therefore it provides a number of theories to estimate the bearing capacity. The purpose of this paper to study the behavior of model square footing in clayey soil subjected to vertical axial loading. The tests are conducted at three grades of undrained shear strength (Cu) of clayey soil which are (20 or 40 or 60 kPa). It is found that, in general, the load settlement curves of raft tests are non-linear hyperbolic shape without a well-defined peak load and the mode of failure is local shear failure in this type of soil, i.e. the behavior of this type of soil is strain hardening. Moreover, the bearing capacity factor (Nc) is equal to (2.8) where this value is not within the acceptable range of the bearing capacity factor (Nc) which ranges from (4 to 6.18) for saturated clay at (φ = 0). The ultimate load may occur at settlement more than (10%) of the width of the foundation which leads to make the settlement criterion control the allowable bearing capacity in design of shallow foundation in this type of soils.