Experimental Investigation of Piled Raft Foundation Under Combined Vertical, Lateral and Moment Loads

Abstract

Piled raft foundation is a rational and economical solution for heavy and tall structures which are typically subjected to combined vertical, lateral and moment loadings. The interaction of lateral, vertical and moment load on piled raft foundation has not been well understood due to the complex interaction of raft, soil and piles. Studies on the behaviour of piled raft foundation system under combined vertical (V)-horizontal (H) and moment (M)-vertical (V) are limited. The V-M-H interaction study using model scale test can provide an insight into the failure mechanism of pile raft foundation. Present study is an attempt to investigate the combined interaction of vertical (V), lateral (H) and moment (M) loads on response of a model piled raft foundation system embedded in sandy soil maintaining relative density in the order of 50%. First, the ultimate vertical and lateral load capacity of only raft and piled raft foundation are obtained from load-deformation behaviour of raft and piled raft foundation. In the next phase, combined loading (i.e. V-M-H) test on piled raft system is carried out and horizontal displacement of piled raft foundation system is recorded with respect to gradually applied H or M loading at a uniform rate in presence of constant vertical load. The vertical load test results indicate that the bearing capacity is significantly enhanced due to inclusion of piles to the raft as a settlement reducer. However, the combined interaction of V-M-H loading exhibits significant variation in vertical and horizontal load capacity as well as horizontal displacement and settlement of piled raft system as compared to the response obtained with independent loading.