Multystory Constructions in the Unconsolidated Quaternary Deposit

Abstract

The Quaternary stratigraphy of the western coastal belt provide soft sub-surface conditions for raft foundations. Within the City of Colombo such raft foundations have been successfully constructed at or below the ground water table, and typically were placed on dense sand beds and on soft sandstones.A well-balanced loading of a raft helps to prevent any tilt during long-term settlements in loose sands and cohesive clays. When the Profiles below the raft are unconsolidated sands, settlements will be mainly instantaneous, during construction loading of the raft. During excavations for a raft below the ground water table, shoring sheet piling and dewatering mechanisms will be necessary.