Assessing Reliability of Drilled Shaft Integrity Testing

Abstract

The reliability of an engineering system can be described as the degree of confidence in the system performing as it is designed or intended to do. This can be assessed by a purely subjective, “gut feeling” reaction from the engineer making judgments based on the test results, or it can be expressed mathematically by considering the reliability of individual system components, together with their relative effects on the performance of the total system. Nondestructive testing (NDT), when used in the quality control of drilled shafts, can be viewed from two extremes: either NDT helps engineers confirm that their design and intended performance criteria are being met, or NDT checks that the contractor has supplied the owner with the product for which the owner has paid (material quality, minimal geometric requirements, etc.). NDT methods currently available are more suited to the first scenario (performance specification). This is supported by analysis of the parameters controlling NDT results and by experience in the United States and in the rest of the world.