Civil Engineering Reference
In-Depth Information
9.2.6.2 Tension pile tests
This test method is similar to compression testing of piles, and maintained load or
constant rate of uplift procedures may be used. The reaction systemmay be provided by
a strong-back resting on adjacent piles or spread foundations. Such a test arrangement
is shown diagrammatically in Figure 9.26. Two jacking points on either side of the pile
are used to avoid bending the test pile, and care is required to load the jacks evenly.
Some cracking of reinforced concrete tension piles is to be expected if loads are high
unless the reinforcement is debonded except in the bottom section of pile.
9.2.6.3 Lateral load tests
For structures carrying major lateral loads it is desirable to carry out lateral load
tests to confirm the design assumptions. The applied loads are relatively small and
it is convenient to use an adjoining pile as a reaction (Figure 9.27). Provision must
be made for a stable datum for deformation measurement as for vertical tests. If
two identical piles are being tested it may be more convenient to measure the rela-
tive movement between them using an extensometer. To increase the reliability of the
back-analysis it is worthwhile measuring the rotation of the pile head. Foundations
are frequently subjected to lateral, vertical and moment loading. It is usually not pos-
sible to arrange for the pile test to mimic such combined loads. Instead, application
of a lateral load near to the ground-level existing at the time is often chosen for such
tests. Similarly it is difficult to simulate fixed head conditions. Data from such a sim-
plified load test may be analyzed using the principles outlined in Chapter 4, and the
computed soil parameters may then be used to predict the response of the pile or pile
group to a more complicated loading regime. Bearing in mind the process of anal-
ysis that has to be used in such circumstances, where possible the testing should be
Figure 9.27
Lateral pile load test. (Photograph courtesy of Westpile Ltd., Uxbridge.)
