Load tests are used to either prove the maximum capacity of piles or verify predicted design values and settlement under pressure.
Where the ultimate load is to be determined the test should be conducted on a pile that is expendable to the main works. A working pile may be used as a test pile but the maximum test load should not generally exceed 1.5 x the safe working load.
Where are they used?
Test piles are generally adopted where, for commercial reasons, a factor of safety of less than 3 using a British Standard (BS8004) design approach or 2 using a Eurocode (EC7) design approach has been adopted.
Where a factor of safety of 2.5 (BS8004) or Eurocode equivalent is used working pile load tests are generally needed. Lower factors of safety will necessitate expendable pile load tests, however all approaches should be discussed and agreed with the relevant checking authorities.
Methods of testing
Central Piling carry out two types of load tests: static load tests with a reaction beam and tension anchor piles, or alternatively dynamic load tests where a weight is dropped on to the pile head by crane.
Static load testing is suited to high pile loadings or single test piles. Whereas, dynamic testing is more appropriate for sites with multiple test piles, low pile loads or where the subsoil is not suitable for tension anchor piles.
Tests are carried out in accordance with the ICE SPERW unless advised otherwise.