Static Pile Load-Movement From Dynamic Measurements

Static loading tests have traditionally been performed to determine the characteristics of pile load-movement relationships. Due to the expense involved and time required, this type of testing is performed on only selected piles on a very limited basis. Lower cost and speed of testing make dynamic pile testing according to the Case Method particularly attractive. These tests allow for an evaluation of the hammer-pile-soil system including pile static bearing capacity. Dynamic data may be further analyzed by the CAPWAP Method to evaluate soil resistance distribution and predict pile load-movement relationship under static loading conditions. This paper presents a general description of CAPWAP and its extended soil model which was most recently introduced by the authors. This soil model allows separation of static from dynamic resistance components such that a static load-set analysis from dynamic measurements becomes possible. Three case studies demonstrate this capability for different hammer, pile and soil conditions. In all three cases, both dynamic measurements and static loading tests were performed. It is concluded that dynamic testing not only can closely predict the pile static capacity, but also the relationship between applied static loads and corresponding pile movements. However, there are minimum requirements for high quality tests which can be expected to yield good correlations.