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Estimating Sheet

How to perform static load testing for piles

Construction Software

The test for static load (SLT) contains the direct calculation of pile head displacement with regards to a concretely functional test load. It is the most basic method of pile load test and is treated as the critical point of pile performance.

Testing is done in the load range 100kN to 12,000 kN. The SLT is performed for the following load configurations:

a. Compression
b. Lateral
c. Tension (i.e. uplift)

For the SLT the load is generally used through a jack performing against a reaction beam, that is controlled with an anchorage system or jacking up against a reaction mass (“kentledge” or dead weight).

The anchorage system may appear as cable anchors or reaction piles set up into the ground to offer tension resistance. The chosen test load is generally used in a series of increments in line with the exact Code, or with a pre-established load testing specification for a project. Each load increment is remained for a certain time period, or unless the rate of pile movement is under a nominated value.

Static load testing methods are ideal for all pile types, on land or over water, and are accomplished on either production piles or sacrificial trial piles. Trial piles are explicitly developed with the aim of executing load tests and consequently, are commonly loaded to failure.

Testing of production piles however, is restricted to ensure that a pile will function suitably at the serviceability or design load as well as an overload to determine that the pile contains some (nominated) reserve capability.

The Test Method: Loading is functional to the test pile through a calibrated hydraulic jack, and where necessary a calibrated load cell calculates the load. Throughout the SLT, direct measurements of pile displacement under the applied loading are assumed by reading deflectometers (dial gauges reading to 0.01mm) which are arranged on glass reference plates cemented to the pile head. The reference beams provide support to the deflectometers which are set up with a certain distance away from both the test pile and any reaction points.

How to perform static load testing for piles

While SLT is usually retained as the most trustworthy form of load testing a pile or pile group, it is vital that interaction effects are reduced. These may be caused by interaction among the test pile and the anchorage systems, or among the measuring system and reaction points. Consequently, proper care is taken to conduct the test in line with exact methods.