Abstract:
Hunter and Davisson (1970) wrote a pioneering paper that brought the presence of residual force and its consequence for pile load-transfer to the attention of the profession. The paper presented observations at the 1963 Lock and Dam 4 project of the Corps of Engineers wherein strain-gage instrumentation was employed for one of the first times in the US. The tests combined results from compression (push) tests with those of subsequent tension (pull) tests and presented an innovative analysis combining the results of compression and tension test on the test pile to determine the true load-transfer of the pile. The analysis established that driven piles would be left with locked-in force distribution— residual force— and that this force affected the evaluation of records from an instrumented static loading tests. While the conclusion that static loading tests should combine push and pull tests and the piles should be instrumented in order for the true load-transfer mechanism be determined was not that often followed by the profession, the paper certainly established the importance of the residual force. This paper re-visits the original test records and analyses.