Driven high capacity H-piles in Hong Kong saprolites: A reliability evaluation of two methods

Abstract

A database for high capacity driven H-piles in Hong Kong saprolites was established so that predicted pile capacities could be compared to values measured by maintained load tests. This gave the statistical attributes that were needed for reliability analyses. Two prediction methods based on set value and dynamic measurements were examined. The uncertainty of a prediction method is characterized by a bias factor. The coefficients of variation of bias factors for both prediction methods are small in the context of geotechnical engineering. A simplified reliability analysis was conducted using the statistical attributes of the database. This enabled an objective assessment of the two prediction methods. Both prediction methods perform equally well relative to the current Hong Kong practice of targetting an overall safety factor of two on geotechnical capacity. The reliability index achieved by current Hong Kong practice for high capacity driven H-piles is in excess of three.