Estimation of the Large Diameter Bored Pile Ultimate Capacity Using Different Design Methods: Assessment Study

Abstract

In this paper, in situ measurements of two well-instrumented loading tests performed on large diameter bored piles (LDBP) have been utilized to assess the reliability of the predicted ultimate pile capacity using three settlement-based and capacity-based methods. The first test was conducted on a short LDBP with a 1.3m and 9.50 length. This LDBP was constructed in stiff clay soil and loaded till the achievement of the failure. While the second in-situ loading test was performed on a long LDBP with a 1.00 m diameter and 34.00 m length. This LDBP was constructed in multi-layered soil and examined under three axially loading and unloading cycles to obtain the ultimate load settlement relationship. Although this LDBP was loaded with an applied load of three times its working capacity, but no apparent failure was reached at the end of the loading test. Thus, two different methods are adopted to interpret the test data and determine the ultimate pile capacity. The obtained ultimate capacities of the two tests were utilized in an assessment study. The comparative analysis results showed a significant difference between the ultimate capacity obtained using three different methods and field measurements. Out of the three utilized methods in this study, the two settlement-based methods underestimated the LDBP ultimate capacity of the two LDBP cases; conversely, the third capacity-based method overestimated the ultimate capacity of the two LDBP cases.