Ultimate bearing capacity of eccentrically loaded square footing over geogrid-reinforced cohesive soil

Abstract

Construction of shallow foundations on weak cohesive soils have limited load-bearing capacity and excessive vertical displacement. This may cause structural damage and reduce the structure’s durability. Traditionally, weak cohesive soils are excavated and replaced with another stronger material layer, or the foundation is enlarged. These procedures are costly and time-consuming. However, these soils are also difficult to stabilize due to their low permeability and slow consolidation. Therefore, it has become necessary to use geosynthetic material. In this study, a square footing model with an eccentric load was tested in geogrid-reinforced clay. The adopted load eccentricity ratios were 0.05 to 0.1, 0.16, and 0.25. Twenty-one tests were executed to estimate the reinforcement influence and eccentricity on the ultimate bearing capacity (UBC). The geogrid improved the BC by 2.27 and 2.12 times compared to unreinforced soil for centrical and eccentrical loads, respectively. The best first layer ratio and the best number of reinforcements were found to be 0.35 and 4. A new equation for BCR with knowing the number of reinforcing layers was proposed and compared with other studies’ outcomes. It was concluded that the foundation tilts in a linear relationship with eccentricity, with a smaller rate inside the core than outside.

Keywords

• bearing capacity
• settlement
• eccentric load
• square footing
• geogrid
• clay soil
• tilt