Experimental study of a shallow foundation on spatially variable soils

The influence of soil variability on the bearing capacity of a foundation has been simulated by various numerical methods. Due to the lack of repeatable tests in spatially variable soil, the effect of the spatial pattern on the failure mechanism of the foundation in a spatially variable soil is physically unclear. This study aims to investigate how the spatial pattern affects the failure mechanism and the bearing capacity of a shallow foundation by the laboratory tests conducted on spatially variable physical soil models. Four physical models were carefully prepared with accurately controlled shear strength according to the random fields of shear strength, which enable the comparison to classical bearing capacity theory. The failure mechanism and the bearing capacity were observed and compared to Terzaghi’s theory in homogeneous soils. Results show that the shear failure plane mainly developed in weak soils, which results in an asymmetric failure mechanism. This different failure mechanism leads to a very different bearing capacity of a foundation on variable soils compared to that on homogeneous soils of the same mean shear strength. This study paves a way towards a safe and economical foundation design by considering the effect of spatial variation in soils.