An Analytical Parametric Study on Behaviour of Flexible Raft Foundation

Abstract

The understanding of soil–foundation–structure interaction is important for design of flexible raft foundation. For flexible foundation, the behaviour would be influenced by the loading as well as the foundation and soil parameters. The present study attempts to understand the influence of the parameters such as meshing size, loading intensity, magnitude of modulus of subgrade reaction (Ks) and raft thickness on base pressure and settlement of flexible raft foundation using STAAD Pro. A symmetrical multi-storeyed building with 25 columns along with raft foundation has been modelled. The building height is varied as 3-storeyed, 6-storeyed and 10-storeyed to simulate different loading intensity and raft thickness is varied as 0.5 and 0.9 m to understand effect of raft rigidity. Ks values of 2000 and 12,000 kN/m3 have been considered for the study. Study concludes that 0.5 m mesh size can be utilized for practical foundation modelling purposes. The effect of Ks on base pressure and settlement variation is more prominent as compared to thickness of raft foundation. Further, the base pressure and settlement increase linearly with increase in storey height. The study presents useful guidelines for the foundation engineers for design of flexible raft foundation.