Effect of Embedment Depth on Bearing Capacity of Strip Footing Placed Over a Spatially Varying c-Φ soil with Non-Stationary Characteristics

The realistic soil strength profiles have spatially varying soil properties as well as varying mean and standard deviation of soil parameters along with the increasing depth. This soil profile with varying soil properties along the depth is modelled using a non-stationary random field. The consideration of spatial variability in soil affects the bearing capacity and failure mechanism and thus plays a vital role in the design of shallow foundations. Studies have explored the bearing capacity of surface strip footings on clayey soil with spatially varying strength properties. However, limited work is available on embedded footing and sandy soil. Hence, this paper aims to study the effects of embedment depth of strip footing placed on a spatially varying c-Õsoil with increasing mean strength values along the depth. The probabilistic analysis is carried out to investigate the bearing capacity with upper bound limit analysis using finite element-based software OPTUM G2 via MATLAB interface. The study covers a comparison of results of non-stationary random fields produced with different strength gradients, and also the statistical characteristics of the resulting bearing capacity are evaluated. A detailed discussion on the effects of vertical correlation length, strength gradient and different coefficient of variations (COVs) ismentioned in the paper. The difference in results due to stationary and non-stationary random fields are also explored.

Keywords: Spatial variability, Non-stationary random field, Probabilistic analysis, Strength gradient, Bearing capacity, Scale of fluctuation.