Stability Analyses for Reclamation Bund on Marine Clay

A container yard is being developed near Mumbai by creating around 90 ha of land through reclamation in sea over soft, compressible marine clay. The thickness of the marine clay varies from 4 to 18 m over the reclamation area underlain by Basaltic rock. The strength of the soft clay varies from very soft to stiff clay, and susceptible to large settlements and shear failure. This stratum cannot support the reclamation fill by its own, hence ground improvement is essential to improve the strength and stiffness properties so that the finished reclamation is able to satisfy the serviceability criteria. Stability analyses of perimeter bund confining the marine reclamation were examined for all probable surfaces including circular, non-circular, and sliding failures as per BS 6031. The analyses show that overfill sections beyond the permanent reclamation cope line are required along with a layer of tension geotextile in order to achieve stability during filling to support the full design load until the cope line. Once the surcharge is removed, the overfill is cut back to the final geometry and revetment is provided along the perimeter bund.