STOCHASTIC MODELING OF DYNAMIC PILE CAPACITY USING HILEY, JANBU AND GATES FORMULAE

J.O. Afolayan and D. A. Opeyemi

Department of Civil Engineering, Federal University of Technology, Akure, Nigeria

Department of Civil Engineering Technology, Rufus Giwa Polytechnic, Owo, Ondo State, Nigeria

E- mail: da_opeyemi@yahoo.com or davidopeyemi@gmail.com, and joafol@yahoo.com

ABSTRACT

The reliability assessment of the load carrying capacities of piles based on dynamic approach using Hiley, Janbu and Gates formulae is reported in this paper, this has become necessary because pile capacities determined from dynamic formulae have shown poor correlations and wide scatter when statistically compared with static load test results. In practice, uncertainties are common phenomena in engineering, therefore all the interrelated variables in the load carrying capacities of piles should be treated as random variables. Assuming practical probability density functions, the concept of the First-Order Reliability Method (FORM) as a powerful tool for estimating nominal probability level of failure associated with uncertainties is therefore invoked for estimating the implied reliability levels associated with the formulae of Hiley, Janbu and Gates. The results show that there is a good correlation between the implied safety levels in Hiley and Janbu formulae, while those associated with Gates are exceptionally different and grossly conservative.   

Key words: Stochastic model, dynamic pile capacity, dynamic pile formulae.