Finite element modelling of deformation characteristics of soft soils in Colombo OCH project

Abstract

This work presents a numerical simulation of the deformation of the earth embankments and soft soil underlying the Colombo Outer Circular Highway. Finite Element analysis software Plaxis 8.2(2002) is used to model the long-term creep deformation behavior of soft soil loaded by embankments, with pre-fabricated vertical drains installed in the soft soil strata. Two constitute models are usedfor the analysis; Mohr-Coulomb Model to represent the earth embankment and Soft Soil Creep model to simulate the soft sub soils. The actual three-dimensional problem domain is converted to an equivalent two-dimensional plane-strain domain. AH field conditions including the load incrementing sequences are simulated, and coupled consolidation/creep analysis is performed to predict the settlement behavior. Numerical predictions are compared with observed field settlement records, and agreement is seen between the predicted results and the observed field measurements, indicating the feasibility of using the numerical model for predicting purposes.