Interference Effect of Footings on Geocell and Geogrid-Reinforced Clay Beds: Fid-Bau Portal

Interference Effect of Footings on Geocell and Geogrid-Reinforced Clay Beds

Sitharam, T. G. / Gupta, Akash

When two footings are placed close enough to each other, they interfere with each other and the soil beneath the footings behaves differently than it would when the footing was isolated. Interference effect causes the soil region between the interfering footings to undergo some sort of confinement due to which the bearing capacity of the soil increases. In this paper, the authors have illustrated how the soil would behave due to interference in clay bed and compared that with clay bed reinforced with geocell confinement. For this, model test experiments were conducted on geocell reinforced clay bed. Three-dimensional numerical simulations using FLAC 3D were run to study parametric study after validating with experimental results. Modified Cam Clay model was used to simulate the behavior of clay bed. Mohr–Coulomb model was used to simulate the behavior of the infill material (i.e., coarse sand). To model the actual shape of the geocell used, the unique and actual curvature of geocell pockets is considered and a realistic approach of modeling is proposed. The optimum spacing (S) between the footings was found to be 0.5 times the width of footing (B) for both unreinforced and geocell reinforced clay beds where bearing capacity is maximum. The maximum interference factor of 1.15 is observed in unreinforced clay. Interference effect is more in geocell reinforced clay than in geogrid-reinforced clay. Maximum interference factor of 1.33 is observed in the case of geocell + geogrid-reinforced clay beds. When the clay was reinforced with geocell and basal geogrid, there was dramatic reduction in the depth of stress distribution, and major stress was accumulated in the geocell membrane preventing the stress distribution to the deeper level.