Settlement Analysis of Soft Clay Using Plaxis 2D: A Case Study from Kochi

Rapid urbanization in Kochi has led to increased construction activities in areas underlain by soft marine clay, which pose significant challenges due to their low shear strength and high compressibility. A multistorey building is proposed at a site in Kaloor, where preliminary geotechnical investigation indicated the presence of soft clay deposits, raising concerns regarding structural stability and long-term performance.In this study, settlement estimation was carried out to evaluate the suitability of the site for construction. Numerical estimation was performed using PLAXIS 2D. The input parameters required for modelling were obtained from detailed laboratory testing and supplemented using empirical correlations. Consolidation analysis was adopted to simulate the time-dependent behaviour of soft clay under applied loading conditions.The simulation results revealed a maximum settlement of approximately 1.36 m, indicating excessive deformation. The volumetric strain reached an extreme value of about −6.9%, confirming significant compression within the soft clay layer. The effective mean stress developed in the soil was approximately −243.77 kN/m², while the total mean stress reached about −407.31 kN/m², indicating high stress concentration within the compressible strata. The active pore water pressure reached values up to −205 kN/m², while the excess pore water pressure was observed to be approximately −10.08 kN/m², indicating gradual dissipation of pore pressure during consolidation.The results clearly indicate that settlement is predominantly governed by the soft clay layer due to its high compressibility, low stiffness, and very low permeability, leading to slow consolidation. The magnitude of settlement significantly exceeds permissible limits, confirming that the site is unsafe for direct construction in its existing condition.Based on these findings, suitable ground improvement techniques are recommended to reduce settlement, improve load-bearing capacity, and ensure safe and stable construction.