Parallel seismic testing by JF Strainstall is regarded as the only reliable method of checking the durability of foundations beneath existing structures.
Occasionally doubts about the integrity and length of concrete and sheet piling, only arises after the structure is complete and pile heads are no longer accessible for testing.
The parallel seismic test has been developed for testing in these situations and is often used to determine the embedded depth of sheet piling, confirmation of pile depth underneath caps and structures, as well as checking the depth of masonry and footings.
Parallel seismic testing methodology
The parallel seismic test works by measuring the time taken for a signal to travel from the top of the pile, to a transducer inside the access tube alongside the pile.
The system hydrophone is lowered down the tube and every 500 millimetres the side of the pile or structure is struck, and the resultant signal from the moment of impact is recorded.
As the hydrophone descends, the rate of increase in signal arrival time will increase. The depth of the foundation is determined by the depth the rate of first arrival changes.