As the duration of the loading is relatively long, piles less than 40 m in length remain in compression throughout, resulting in negligible stress wave effects and potentially simpler analysis.
The simplest form of Statnamic analysis used to obtain equivalent static pile response is known as the unloading point method (UPM).
[2] The Statnamic test applies a force to the pile head over a typical duration of 120 milliseconds by the controlled venting of high-pressure gas.
At some point the pressure within the piston is of such a magnitude to force the load hanger arrangement upward at accelerations in order of 196m/s2 (20g).
Pile settlement is measured using a remote laser reference source that falls on a photovoltaic cell incorporated in the piston.
The laser reference source should be placed at least 15 m from the test pile to avoid the influence of test-induced ground surface wave disturbance (Brown & Hyde, 2006).
To achieve greater loads the major components of the device, including the piston, silencer-weight hanger and reaction mass, must be scaled up in size.
[1] The most recent development is the mounting of a 1 MN Statnamic device on a 360° tracked excavator which allows rapid deployment (1 hour) and increased production.