Model test on the axial capacity of displacement ribbed piles

Abstract

The capacity, hence the load-settlement behaviour of a pile is governed by the collective behaviour of the base and shaft. It is highly desirable, sustainable and economical to accommodate the increasing demand for deeper and wider foundations through the use of higher capacity piles. This research investigated the performance of preformed displacement ribbed piles in a unit gravity model test. Four tests were carried out to replicate the constant rate of penetration (CRP) test in the field. Two lengths corresponding to short and long piles for each of plain and ribbed piles were employed. Compacted Kaolin S300 type was employed as the model soil. The failure load of the piles was determined using six different methods. An increased capacity of 32% and 20% was obtained in the short and long ribbed piles, respectively. Also, it was observed that the closer the distance between the ribs, the higher the capacity produced for equal number of ribs. The ribbed piles gave higher capacities through the increase in their shaft capacity which is associated with the presence of ribs along their lengths. An increase in the axial capacity of displacement piles can be attained by modifying the profile of the pile shaft through the use of ribs.