State of Practice—Dynamic Load Test Monitoring of Driven Piles in the United States

Dynamic load test (DLT) on driven piles is a common practice worldwide in accordance with ASTM Standard D4945-17 [1]. In many countries, DLT is often carried out after the test pile installation has been completed. However, in the United States, the whole test pile driving process—especially with concrete piles—is fully monitored with instrumentation using the DLT system. This paper presents the state-of-practice of the DLT of driven piles in the United States, including the following steps: (1) Evaluation of hammer suitability through wave equation analysis, which has limitations due to unknown quake, damping, cushion stiffness, and pile resistance distribution, but can be used to preliminarily assess whether the pile driving hammer is capable of safely installing the piles. (2) DLT from the very first blow of the pile installation, to monitor pile stresses, integrity, and resistance during driving. (3) DLT setcheck or redrive (if necessary). (4) Post-test wave equation analysis, using quake, damping, and resistance distribution from step 2. (5) Pile Driving Criteria recommendation on how to safely install subsequent production piles based on step 4. The paper provides a case study and illustrations that help formulate a big picture of the DLT monitoring process. The presented state-of-practice in dynamic load testing of driven piles in the United States is an essential reference for engineers, researchers, and practitioners in the field of foundation design and construction.