LOAD CARRYING CAPACITY OF PILED –RAFT SYSTEM USING NUMERICAL APPROACH by Himani Chawla
Abstract
The foundation system is an important component from the civil engineering point of view in general and it is the duty of geotechnical expert to take care of the safety and stability of foundation of civil engineering projects. The pile raft foundation system is a composite foundation which contributes the involvement of piles, raft, and soil to transfer heavy loads of the superstructure to the ground. The utilization of piled-raft system is an efficient way of reducing both total and differential settlements, enhancing the bearing capacity of a foundation. The analytical work includes the numerical analysis of pile raft foundation under the effect of variable ground water table by generating a numerical model in FEM based PLAXIS 3D software. As piled-raft foundation system is the main concern of its effectiveness because it is the most refered foundation system especialy for the high rise buidings . The relevence of the system comes when one system works efficiently under the adverse subsoil condition at the cheaper cost than the other foundation system. Adverse subsoil conditions comes when the foundation system was encountered with ground water table.The bearing capacity of the saturated soil reduces to about 50% of its orignal bearing capacity in its dry state.The large reduction in the bearing capacity is the serious concern for the geotechnical engineers. So here comes the need to analyse the effect of ground water table on the foundation system.In this study an effort has been made to analyze the experimental results of piled raft using PLAXIS 3D software.With the experimental investigation it is very difficult to study the effect of ground water table variation on the load carrying capacity of the piled raft but using the FEM based PLAXIS 3D this problem can be addressed easily. The study highlights that there is significant reduction in the ultimate load (decreases from 7731.29kN to 5659.68kN when there is rise in ground water table from great depth to ground surface
