Parametric Study on Behaviour of Retrofitted Piled Raft Foundation

Abstract

Mat supported on piles is being increasingly used for high-rise buildings with basements in poor soils. Very little is known about the exact behaviour of piled raft foundations in service. However behaviour of retrofitted piled rafts, which are a hybrid foundation of mat provided as retrofitting solution and failed pile foundations, is non-identical. In order to model the mat for retrofitting, engineer needs to analyze the sensitivity of different parameters to their behaviour. In this paper, a numerical analysis has been carried out to investigate the influence of mat thickness and soil subgrade modulus of uniform and varying values to the behaviour of mat foundation rendered to retrofit a short felled pile foundation executed for a high-raised building in Kerala, by using finite element software SAFE v 16. The soil and the piles are modeled as spring element at discrete position below the mat and the mat foundation is modeled using elastic plate element. The results of the study show that mat thickness and soil subgrade modulus are found to be the governing parameters in designing a safe and economical retrofitting mat foundation. Furthermore, it is recommended to provide exact soil subgrade properties under the mat to perceive actual behaviour of foundation.