Assessment of empirical methods for interpreting bidirectional pile load test results

Abstract

There are many available methods to convert the O-cell pile load test results into the Equivalent Top Load (ETL) curve. That curve should be representative of the load-settlement curve measured during the equivalent conventional test. This paper assessed the available empirical methods to investigate their capability of reproducing the measured conventional test results. The assessment was performed by applying these methods to several well documented cases of O-cell pile load tests to find the corresponding ETL curves. These estimated curves were compared to reference curves produced from simulated equivalent conventional tests using the finite element method. The judgement was based on finding the error in the settlement at expected working loads and the ultimate carrying capacity of the pile estimated from the ETL curve. Throughout the assessment, it was noted that the different interpretation methods produce significant errors, indicating the need for a new method that minimizes the error values.