Performance Evaluation of Piled Raft Foundations in Layered Soil Under Different Piled-raft Configurations using Numerical Methods

Abstract

Large civil constructions that are frequently built on soft soil sites due to rapid urbanization can lead to settling, particularly in urban regions with few rock sites. Despite their significant weight, high-rise buildings must have minimum differential settlement in order to comply with strict safety rules. Through the creation of a composite foundation, in which the piles serve as settlement reducers and share the load from the superstructure with the raft, piled raft foundations have been successfully utilized for the past four to five decades all over the world to maximize the foundations of civil engineering structures. In these foundations, piles share the load of the superstructure with the raft and serve as settlement reducers. Numerical methods are often required because of the intricate soil structure interaction in pile raft foundations and the lack of field data. In this study, the load-settlement behavior of piled raft from previous numerical works was analytically simulated to validate the 3D finite element model. When uniform vertical force is applied to layered soil, the effectiveness of a rectangular combination piled raft system with different piled raft configurations have been assessed. The analysis looks at the effects of several factors using Plaxis 3D, a strong finite element tool taking constant number of piles 16. The reaction of piled-raft foundations is also examined parametrically, taking into account the effects of raft thickness, pile length, pile spacing, and pile diameter. It was found that the differential settlement was decreased by 59.92% and 57.26% for uniform piled raft configurations and non-uniform piled raft configurations by raising the raft thickness from 0.7 to 1.7 meters, respectively. The maximum settlement did, however, rise by 0.19% and 0.69% for uniform piled raft configurations and non-uniform piled raft configurations, respectively. The maximum settlement amount was decreased by 3.0% and 3.30% for uniform and non-uniform piled raft configurations, respectively by increasing pile spacing from 3D to 4D. Additionally, from the total settlement reduction obtained by increasing pile length from 9m to 12m, the maximum settlement was reduced by 7.85% and 17.42% for uniform piled raft configurations and non-uniform piled raft configurations, respectively. Hence, the findings from the current research can give deep insight into understanding of different piled raft configurations performances under uniformly distributed vertical load.