Finite element analysis of piles as settlement reducers in raft foundation

• Main Author: Chan, Wei Yi
• Other Authors: Teh Cee Ing
• Format: Final Year Project
• Language: English
• Published: 2019
• Subjects: DRNTU::Engineering::Civil engineering
• Online Access: http://hdl.handle.net/10356/78452
• Institution: Nanyang Technological University

Shallow foundations such as rafts often face the problem of excessive settlements despite having adequate load-carrying capacity. Hence, they are usually replaced with more conservative and costly foundation designs such as piles to achieve both bearing capacity and serviceability requirements. Piled raft foundation with settlement-reducing piles is a feasible and economical alternative to reducing both the total and differential settlements of raft by considering the bearing capacity contributions from raft and piles. Past studies by geotechnical researchers have found that the complicated design of piled raft is affected by parameters such as pile dimensions and arrangements. Therefore, a parametric study is carried out to understand how the settlement of piled raft in stiff clay is affected by pile dimensions and positions on the raft using the finite element analysis tool PLAXIS-3D. In this study, two pile length to diameter (L/D) ratios of 15 and 25 will be modelled in three different arrangements on the raft. The results showed that piles with larger L/D ratio are more effective in resisting applied loading and reducing settlements. Furthermore, rafts that contain a combination of piles concentrated in the middle and piles distributed along the edges are more efficient in load transfer as the piles share majority of the loading at working load state. In addition, a case study on the piled raft foundation of Torhaus der Messe is used to validate the competency of PLAXIS-3D to provide accurate analysis of piled raft foundations.