ABSTRACT
Pile tests are an important means to cope with uncertainties in the design and construction of pile foundations and avoid the use of excessively conservative designs. Both quantitative tests, such as static or dynamic load tests, and qualitative integrity tests, such as coring examination and cross-hole sonic logging, are routinely employed. Pile tests serve several purposes. Some of their functions include verification of design parameters (this is especially important if the geotechnical data are uncertain), establishment of the effects of construction methods on foundation capacities, meeting regulatory requirements, and provision of data for the improvement of design methodologies in use and for research purposes (Zhang 2004). In addition to these functions, savings may be derived from pile tests. With pile tests, lower factors of safety (FOSs) or higher-strength parameters may be used. Hence, there are cost savings even when no changes in the design are made after the tests. For example, the U.S. Army Corps of Engineers (USACE) (1993), the American Association of State Highway and Transportation Officials (AASHTO) (1997), and the Geotechnical Engineering Office (2006) recommend the use of different FOSs depending on whether load tests are carried out or not to verify the design. The FOSs recommended by the USACE are shown in Table 14.1. The FOS under the usual load combination may be reduced from 3.0 for designs based on theoretical or empirical predictions to 2.0 for designs based on the same predictions that are verified by a sufficient number of proof load tests.
