Performance of square footing on geogrid reinforced soft clay

Abstract

Developing mega structures like highways and railways, bridges, and tall buildings constructed over soft clay becomes challenging for geotechnical engineers. Soft clays are considered problematic soils as they possess high compressibility and low shear strength. There are several methods for improving in situ conditions of soft clays. This research focuses on using geogrid to improve soft soil and increase its stability under loaded square footing. A model test was developed in this study for square footing resting on soft clay to investigate the effect of uniaxial geogrid to control the soil settlement and enhance its shear strength. The results of the experimental model were compared with the analytical solution using the finite element program ABAQUS, where a good agreement was found between the computed and measured data. The second objective of the research was to focus on the parameters that increase the bearing capacity of soil and hence reduce the settlement other than the parameters used in the verification case. This was achieved by conducting parametric studies using the developed numerical model. The Parametric studies focus on the role of different parameters that affect the interaction mechanism between the soil and geogrid. These parameters included the number of geogrid layers, the first geogrid location, and the geogrid length. Also, the impact of creep settlement of reinforced soft clay was considered. It was found that placing geogrid layers at depth not less than 1.3B where, the first geogrid located at distance U = 0.7 under the footing is more appropriate for improving soft clay properties. Also, the length of geogrid should be not less than 3B to be effective in reducing the consolidation settlement of the soft clay. Moreover, the geogrid layers are ineffective in reducing the settlement resulting from creep.