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Technical Note (National Research Council of Canada. Division of Building Research), 1957-03-01
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Pile Loading Tests
Eden, W. J.
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DIVISION OF BUILDING RESEARCH
221
NOTE
TEClHIN leAL
NOT FOR PUBLICATION FOR INTERNAL USE
PREPARED B'W0 J. Eden CHECKED BY APPROVED BY
RFL
SUBJECT
PREPARED FOR
distribution by the Associate Committee on Soil and Snow Pile Loading Tests
DATE March, 1957
Mechanics
ｾ
The Joint Committee on ｾｩｬ･ Driving of the Institution of Civil Engineers of Great Britain is attempting to gather data on pile loading tests so ｴｨ｡ｾ a better method of assessing the ｵｬｴｩｾ｡ｴ･ bearing capacity of piles can be established.
To do ｾｯＬ the co-operation of practising engineers and piling contractors is essential. The questionnaire from the Institution included with this note indicates the information required.
The following is extracted from the preamble to the questionnaire:
The method.s used for testing piles vary according to local circumstances and equipment available. They also depend on the experience and preferences of the engineers. If the tests are to be correlated and analysed it is essential that
they should be conducted in accordance with a standard procedureo A brief summary of the recommended method follows; further details can be obtained in "The Chartered Civil Engineer", May 19500
The load should be applied in stages and no increment of load should be added until the settlement from a constant load is seen to have practically ceased. With the load kept constant, readings of the settlement should be taken at intervals of time. These should be plotted on a graph showing settlement against time and from the trend of the curve it will be found possible to
judge when movement has virtually ceased. This procedure is
especially important with plastic soilso As a general indication, a limiting rate of ｭｯｶ･ｾ･ｮｴ of l/SO inch in
6
hours may be taken and used, particularly with clay soils. When equilibrium is reached a further increment may be applied and the procedure repeated until the ultimate load is reached or very closely approached. A load/time settlement diagram can then be drawn.- 2
-the relation between -the magnitude of -the load and -the corresponding settlement when equilibrium is reachedo The first increment of load may be large, amounting to one third
or one half the anticipated ultimate load. Subsequent increments should be decreased until failure takes place. It is important that loading should continue until the ultimate load has been attained or can be estimated with sufficient accuracy.
It is important that reports on test loadings should be accompanied by the results of a site investigation. Test loadings without detRiled information about the nature of the soil are of
Ii ttle value.
To simplify the recording and analysis of test results, the information required by the Committee has been set out in the attached questionnaire. The Committee hope that engineers will use this as far as it is applicable and will supplement it with additional information where required. Each pile loading test
should be reported on a separate form. Further copies of the questionnaire are available on request.
The Committee will also welcoroo data concerning tests on groups of piles, especially if the results can be related to tests on similar single piles in the same ground. Finally, the Committee suggest that engineers do not confine their reports to tests on piles which developed the desired bearing capacity. Information about piles which failed to satisfy the requirements may well be of even greater value.
The Associate Committee on Soil and Snow Mechanics will gather the information available in Canada for transmittal to the Institution of Civil Engineers. If you have such information or know of anyone who could help, kindly complete the questionnaire part of this note and send i t to:
The Secretary,
Associate Cbmmittee on Soil anq' Snow Mechanics, National Research Council,
ottawa.
Additional copies of the questionnaire may also be obtained from the Secretary.
QUESTIONNAIRE
A.
Site InvestigationAI. Location and name of contract.
A2.
Was an investigation of thesoil on the site made prior to piling?
AJ. To what depth or datum level was the investigation made?
Ah.
Were the soil strata sampledand identified?
A5.
Were the properties of the soils determined for the strata at different depths?Ab.
Was any stratum sensitive,"quicklll
ll or in any way ex-ceptional?
A7. Was a sounding, penetrometer
tests! standard penetration test
or "Dutch cone" test performed?
AB. Can the results of any boring or test be related specifically to the te st pile?
A9.
Did the sequence of strata determine the type of pile used?Give brief indication of method.
A diagram showing the thick-nesses and types of strata
should be appended.
Relevant information should be appended.
Relevant information should be appended.
Relevant information should be, appended.
A plan indicating positions and datum levels of borings and test pile should be appended.
4
-Bo Test Pile
BI. Type of pile and method of installation (driving, boring or jacking).
B2 0 Material and construction.
B3. TIimensions of pile; overall length; cross-section; shape of point; size of enlarged base, if any"
B4.
Weight of pile.B5.
Length driven.B6.
(a) Was test pile especially installed for test purposes? (b) If answer to (a) is ｾｎｯｾＬ wasthe pile chosen from those forming the foundation being constructed» and how was the choice made?
B7. Reference number of test pile and position in relation to other piles or foundations. If pile is one of a group, state position in group and sequence in which piles in the group were
driven.
B8. Date of driving or installation. Date of testing.
ｾ｡ｷｩｮｧ to be appended
if necessary.
The position of the test pile in the known strata should be given on an appended diagram.
B90 Penetration per blow of hammer at end of driving.. A complete Driving Record in accordance with Appendix ａｾ Civil Engineering
Code of Practice Noo
4:
Foundations (page78)
should be appended.BIG.
If pile driving was interrupted,state idle period and any change in set per blow when driving re-commenced.
BII. Condition of pile head at end of drivingo
c.
Pile Driving Equipment Cl. Type of hammer and method of'operation.
C2. Weight of' ram and stroke or fall. If' a ､ｯｵ｢ｬ･ｾ｡｣ｴｩｮｧ ｨ｡ｲｾ･ｲ was used, state size, and number of blows per minute during final penetration.
C3. Weight of helmet with dolly and hammer anvil ..
c4.
Type of' packing and dolly on pile head and condition at end of driving.Do Test Method
Dl. Was the test made byg
(a) Dead load on the pile head? (b) Jacking against kentledge or
. " _1
6
-(c) Jacking against anchor piles? (d) Some other method. (Please
describe) Q
D2 0 In the case of method (a)
at what distance was kent ledge stored before transfer to the pile?
What provision was made to ensure centrally applied load?
In the case of method (b)
ｾｾ｡ｴ was the total kentledge load?
ｾ｢･ｲ･ was this supported in relation to the test pile? In the case of metborl (c)
ｾｾ｡ｴ was the position of
anchor piles and their lengths?
D3.
Was the test made by:(a) incremental steps of load? (b) maintaining a constant rate
of settJe ment?
(c) maintaining a constant rate of loading?
(d) some other method (please describe)?
n40
How was settlement measured? Give distances from test pile of any stakes carrying gauges orreference wires, and the nature and location of the reference datum.
Plan to be appended.
7
-D5.
vVhat was the preclslon of the measurement of settlement?With what error could readings be repeated?
E. Test Results
El. Was the pile loaded to failure?
E2. Test results should be appended. They should be in the form of a table gi ving tile load and settle-ment and the time of the observation, with any other relevant data. If diagrams or graphs have been prepared these should also be given.
E3. ｾｾ｡ｴ was the ultimate load at failure derived or estimated from the test?
E4.
What is proposed safe working loadper pile?
Fe Supplementary Observations
Fl. Are any records available of the heave or sinking of the ground
surface caused by piling operations?
F2. Were piles observed to rise due to the driving o'f adjacent piles?
Any records of lifting or redriving should be given.
F3. Are settlement records showing the behavior of the structure to which this report relates likely to be available in due course?
