These methods are founded upon the concept that pile penetration under each blow induces failure of the soil, hence, an instantaneous load test is performed. The reliability of these analyses is enhanced through data obtained by dynamic measurements during driving. Two methods are currently employed for the analysis of the measured data. Both methods are based on the solution of the one dimensional wave equation for the stress wave traveling through the pile following the hammer's impact.
Substantial experience suggests the existence of major limitations to the field method.
In addition, no large scale evaluation has been carried out for the office methods since their development. A simplified method based on energy balance is proposed as an alternative field method. Calculated transferred energy and maximum pile displacement from the measured data are used as input parameters for the Energy Approach. Two large data sets were gathered at the University of Massachusetts at Lowell. The other, PD, contains data on 403 piles monitored during driving and was provided by Pile Dynamics Inc. of Cleveland Ohio.