Volume 6 – Geotechnical Manual, Site Investigation and Engineering ...

Chapter 9 FOUNDATION ENGINEERING
b) Maintained-load tests
In a maintained-load test, the load is applied in increments, each being held until the rate of
movement has reduced to an acceptably low value before the next load increment is applied. It is
usual practice to include a number of loading and unloading cycles in a loading test. Such cycles can
be particularly useful in assessing the onset of plastic movements by observing development of the
residual (or plastic) movement with increase in load.
Details of the common loading procedures used in Hong Kong GEO which can be used as a guide are
summarised in Table 9.4.
When testing a preliminary pile, the pile should, where practicable, be loaded to failure or at
least to sufficient movement (say, a minimum of 5% of pile diameter). If the pile is loaded beyond 2
W L
, a greater number of small load increments, of say 0.15 to 0.2 W L
as appropriate, may be used
in order that the load-settlement behaviour can be better defined before pile failure. However,
the test load should not exceed the structural capacity of the pile.
In principle, the same loading procedures suggested for compression tests may be used for
lateral and uplift loading tests.
9-22 March 2009