Standards of Japanese Geotechnical Society
for Vertical Load Tests of Piles
(English Version)
• JGS 1811.-2002
Method for Static Axial Compressive Load Test of Single Piles
• JGS 1812-2002
Method for Static Pile-Toe Load Test of Single Piles
• JGS 1813-2002
Method for Static Axial Tensile Load Test of Single Piles
• JGS 1814-2002
Method for Static Axial Reciprocal Load Test of Single Piles
• JGS 1815-2002
Method for Rapid Load Test of Single Piles
• JGS 1816-2002
Method for Dynamic Load Test of Single Piles
April
2002
The Japanese Geotechnical Society
COPYRIGHT
The Japanese Geotechnical Society
Sugayama Building, Kanda Awaji-cho 2-23, Chiyoda-ku, Tokyo, 101-0063, Japan
Telephone 81-3-3251-7661, Telefax 81-3-3251-6688, E-Mail
jgs@jiban.or.jp
URL h!!P.J.f.:ww.~j!h<l!le_Q!",lli
Published in 2002
Edited by
committee for Standards for Vertical Load Tests of Piles, Standardization Division,
Japanese Geotechnical (Society Please note that the Japanese text must be considered as the standard manuscript and
the English version is provided only as a reference.)
All rights reserved. This material may not be reproduced or copied in whole or in part, in any printed, mechanical,
electronic, film, or other distribution and storage media, without the written consent of the publisher.
''V
The Japanese Geotechnical Society expresses its deep gratitude to the Committee on ISO Affairs
in Civil Engineering, the Japanese Society of Civil Engineers, for the grants in translation and
Publication
FOREWORD
The Japanese Geo technical Society has been taking the lead in establishing the standards for load
tests on vertically installed single piles subjected to axial loads by publishing the society
standards for 'vertical load test of piles' and 'pull-out test of piles'. This publication covers the
standards and basic descriptions concerning six different methods of load application for the
vertical load test of piles.
One important feature of this standard is consideration of the behavior (load-displacement
relationship) of pile under the action of vertical loads in terms of the basic equation of motion
during penetration of pile into the ground. It has been common to classify load test of piles as
static (pile head loading and pile toe loading) and dynamic. However, by considering the pile
behavior in terms of the equation of motion, it has been made possible to consider the different
load application methods ranging from static to dynamic in a consist manner, while at the same
time clarifying the scope of individual load test methods. This approach constitutes a
distinguishing feature of the current standard.
Until now it had been usual to consider the 'vertical load test of piles' as referring only to the
method of applying static load at the pile head to push the pile vertically downward. However,
the equipment for conventional static loading system became large in tandem with the higher
design capacity of piles in recent years and the consequent exponential increase in the cost meant
that load tests are seldom performed in general construction practice in recent years.
With the advent of performance based design, appropriate consideration of load-displacement
relationship becomes necessary in the design of pile foundations and the practice of determining
the pile capacity based solely on the pile bearing resistance, with disregard to settlement, would
not be desirable. The standard provides adequate choice to designers by covering six different
methods of vertical load test of piles. However, it is imperative that the designers fully
understand the scope and limitations of various methods, and select the method suitable for the
performance of the structure being designed, such that an efficient load test that provides a
optimum balance between cost required and information desired is adopted.
Finally, I would like to express my sincere appreciation to members in the committee for their
diligent work in course of this publication. I would also like to thank various individual members
of the Japanese Geotechnical Society who have contributed in various ways in the process of
developing this standard.
Hideaki KISHIDA
President, The Japanese Geotechnical Society
Apri12002
Committee for Standards for Vertical Load Tests of Piles,
Standardization Division, Japanese Geotechnical Society
Okahara, M. (Chairman)
Public Works Research Institute
Kuwahara, F. (Vice Chairman)
Nippon Institute of Technology
Kishida, H. (Adviser)
Tokyo University of Science
Fujita, K. (Adviser)
Geotech Corporation
Aoki, H. (Secretary General)
Japan Railway Construction Public Corporation
Ichimura, Y. (Secretary)
National Institute for Land and Infrastructure
Management
Ogura, H.
GEOTOP Corporation
Kishi, T.
Honshu-Shikoku Bridge Authority
(Ishida, M. )
National Institute for Land and Infrastructure
Management
Nishimura, S.
Fugro Geoscience Co., Ltd.
Fujisawa, H.
Jibanshikenjo Corporation
Inamura, T. (Member)
Toyotechno Corporation
Ogata, T.
Japan Railway Construction Public Corporation
Kikuchi, Y.
Port and Airport Research Institute
Sakimoto, J.
Obayashi Corporation
Hayashi, M.
NKK Corporation
Futaki, M.
National Institute for Land and Infrastructure
Management
Fuyuki, M.
Tokai University
Horikoshi, K.
Taisei Corporation
Maeda, Y.
Kyushu Kyoritsu University
Matsumoto, T.
Kanazawa University
Yamashita, K.
Takenaka Corporation
Yamato, S.
Asahi Kasei Construction Materials Co., Ltd.
Yajima, J.
Tokyu Construction Co., Ltd.
CONTENTS
Page
Designation:
JGS 1811-2002
Method for Static Axial Compressive Load Test of Single Piles • • • • • • • • • • • • • • • • • • • • • • • • •
Designation:
JGS 1812-2002
Method for Static Pile-Toe Load Test of Single Piles··•···········••···········•··•••••
Designation:
1
1
JGS 1813-2002
Method for Static Axial Tensile Load Test of Single Piles•···••••••••·•••••••••••••····· 13
Designation:
JGS 1814-2002
Method for Static Axial Reciprocal Load Test of Single Piles • • • • • • • • • • • • • • • • • • • • • • • • • • • 19
Designation:
JGS 1815-2002
Method for Rapid Load Test of Single Piles • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 25
Designation:
JGS 1816-2002
Method for Dynamic Load Test of Single Piles······•••·····••••••••···••••••••·•··•·· 31
Method for Static Axial Compressive Load Test of Single Piles
(JGS1811-2002)
1.GENERAL
the following points: the objectives of the test, the ground
conditions, the loading conditions, the required period
1.1
Scope
and costs, the installation methods, the pile dimensions,
These standards shall be applied to static load tests
the number of piles, the pile head level, and the
(hereafter referred to as "test(s)") in which a single pile
arrangement of working piles, etc.
vertically installed is subjected to a static axial
2.2
compressive load.
1.2
1)
Objectives of test
Planned maximum load
Based on the test objectives, the planned
maximum load shall be determined to be more
The objectives of the test are to obtain information on
than either the second-limit-resistance of a pile, or
the vertical bearing capacity of a single pile and/or to
the product value of the design load multiplied by
ensure the predetermined design capacity of a pile.
the safety factor.
1.3
Terminology
2)
Descriptions of terms specific to this standard:
When the conditions of the test pile(s) are
different to the working piles, the planned
Static load : A load under which test results shall not
maximum load shall be determined carefully
be affected by velocities and/or accelerations
considering the effects of the different conditions
of the pile body and soil.
upon the bearing capacity of the test pile(s).
Planned maximum
load
: The pre-specified
23
maximum load which is estimated to be
Specifications, number and location of test
pile(s)
adequate for achieving the test objectives.
1)
Step loading method : A loading method in which
Test pile(s) shall be designed to have the same
properties as working piles, and shall be planned
the load is applied in several loading steps,
separately from the working piles.
and is maintained for a period of time at
2)
each step.
Working piles can be used as test piles if the
working piles are strong enough, and the tests do
Continuous loading method : A loading method in
not affect the superstructure.
which the load is applied continuously in a
3)
The number of test piles and their locations shall
smoothly increasing and decreasing manner
be appropriately selected based on the objectives
without holding one load level for an
of the test.
extended period of time.
Tf!Orking pile : Pile that
2.4
is used as part of a
Test equipment
The reaction device shall be selected from (a) reaction
practical structure.
piles, (b) ground anchors, (c) kentledge, and (d) a
Test pile : Pile upon which tests are performed.
combination of the above devices.
Pile diameter : The outer diameter of a pile.
2 ..5
Maximum pile diameter : The largest of the
1)
Method of loading and measurements
The loading pattern shall be chosen from the step
diameters of a pile body or an enlarged
loading method and the continuous loading
section.
method to achieve the required test objectives. In
the step loading method, the numbers of loading
2. BASIC PIANNING
steps, the number of cycles, and the holding times
shall be decided. In the continuous loading
2.1
Basic items
method, the number of loading cycles and the
The basic items of the test are the number of tests, the
loading rate shall be decided.
planned maximum loads, the specifications and locations
2)
of the test piles, the loading and measuring methods, the
Measurement items and devices shall be arranged
according to the objectives of the test.
system of executions, and so on. In planning the test, the
basic items should be determined by taking into account
-1-
3. TEST PREPARATION
long enough to allow for the recovery of soil
strength and the hardening of pile materials such
3.1
Preparation of the execution plan
In advance of the test, an execution plan shall be
as concrete and cement mix, etc.
4)
During the curing period, care shall be taken not to
formulated and documented based on the basic plan and
apply any loads, impacts or vibrations to the test
field inspections.
pile(s) that might influence the test results.
The plan shall include the following items:
(1)
Test objectives
(2)
Ground conditions
(3)
Planned maximum load
(4)
3.4
1)
The test equipment shall be precisely set up
according to the execution plan.
2)
Specifications, locations, and installation
Adequate countermeasures against sunshine, wind
and rain shall be taken in order to avoid harmful
method of the test pile(s)
(5)
Setting up test equipment and test site
effects on the test results.
Assembly drawing of the test equipment
3) The effects of the construction work, machine and
(6)
Specifications of hydraulic jacks
vehicle operation nearby the site shall be
(7)
Design calculations of the reaction system
examined. As the occasion demands, some
(8)
Specifications and installation methods of
measures shall be taken to minimize their effects.
reaction bodies
(9)
4. TEST EQUIPMENT
Items to be measured
(10)
Compositions, specifications and positions of
4.1 Composition of test equipment
1) The test equipment consists of loading devices, a
the measurement devices
(11)
Loading method
(12)
Time sequence of measurements
reaction system and a measuring system.
(13)
Composition of testing personnel
(14)
Items to be recorded
2) The loading devices consist of hydraulic jacks, a
pumping unit and a base plate between the pile
(15)
Processing of test results
head and the hydraulic jack.
(16)
Schedule
(17)
Points to pay attention to during the test
3) The reaction system consists of reaction bodies,
such as piles or ground anchors, and loading
3.2 Design of test piles
1) The test pile(s) shall have strength with a sufficient
2)
beams together with their connectors.
4)
margin of safety against the planned maximum
devices, reference beams and reference points.
load.
The measuring devices consist of data acquisition
The test pile(s) shall have enough length above the
and display equipment as well as sensors such as
ground surface to allow setting up the loading
load
devices,
transducers and strain gages.
reaction
system,
reference
beams,
The pile head shall be reinforced adequately in
order to avoid damage due to accidental eccentric
2)
When friction cutting is performed, the potential
gages,
displacement
The hydraulic jacks shall be calibrated and
inspected before the test. The standard hydraulic
for a buckling failure of the pile body shall be
jacks shall have spherical seating.
considered.
3.3
1)
pressure
of safety against the planned maximum load.
loads.
4)
cells,
4.2 Loading devices
1) The loading devices shall have a sufficient margin
measurement devices, and so on.
3)
The measuring system consists of measuring
3)
The hydraulic jacks shall have a sufficient
capability for the planned maximum load, and a
Installation and curing of test piles
The test pile(s) shall be installed in the same
sufficient stroke length to follow the deformations
manner as the working piles.
of the test pile and the reaction system.
4)
2)
The installation process of the test pile(s) shall be
3)
The test pile(s) shall be cured for a period of time
The hydraulic jacks shall be set up correctly on the
center of the test pile without eccentricity.
recorded in detail.
5)
When several hydraulic jacks are used, the jacks
shall have identical specifications and shall be
-2-
controlled simultaneously.
6)
shall have adequate accuracy to achieve the test
The hydraulic pumping unit shall have a sufficient
oil supplying
capacity
objectives.
2) The sensors shall be firmly set in their appropriate
against the planned
maximum load and the planned loading rate.
7)
3)
The base plate shall be sufficiently rigid for the
planned
4.3
positions and proper directions.
maximum
load
and
shall
be
set
good care in order to prevent any influences due
horizontally.
to the displacement and/or the deformation of the
Reaction system
loading devices and reaction system.
1) The reaction system shall have a sufficient capacity
4.5
As a general rule, the reaction device shall be
piles or temporary piles.
2) When the reference points are located on a the
arranged symmetrically to the test pile.
3)
Reference points and reference beams
1) Reference points shall be located on either working
against the planned maximum load.
2)
The measurement devices shall be set up with
As a general rule, the distances between the centers
working piles, they shall be positioned away from
of the test pile and the reaction piles, or between
both the test pile and the reaction piles at distances
the centers of the test pile and the ground anchors,
of more than 2.5 times as long as the test pile
shall be more than 3 times the maximum diameter
diameter.
of the test pile, and also more than 1.5 meters.
3)
When the reference points are located on a
4) When working piles are used as the reaction piles,
temporary piles, they shall be positioned away
attention should be paid not to damage the
from the test pile at a distance of more than 5
working piles.
times as long as the diameter of the test pile, and
5) When ground anchors are used, elongation of the
tendons
shall
be
carefully
considered
more than 2 meters. Also they shall be positioned
and
away from the reaction piles at distances of more
countermeasures shall be taken to ensure the
than 2.5 times as long as the diameter of the
smooth execution of the test.
reaction piles.
6) The anchor body shall be installed at a depth where
7)
4) The reference points shall be positioned more than
its influence on the bearing capacity of the test
2.5 meters away from the ground anchors with
pile will be minimal.
their reaction plates, the supports for kentledge
Supports shall be provided in order that the
and the loading beams.
5)
weights of the loading beams and/or the actual
reaction weight do not directly rest on the test
reference points. Good care also shall be taken to
pile.
8)
minimize the influence of the deformation of the
Loading beams shall be safe against failures of
. beams due to fluctuations in temperature.
bending, shearing and buckling, and against
4.4
1)
The reference beams shall be firmly fixed on the
6)
The reference points and the reference beams shall
damages at reaction points, and also shall be
be sufficiently rigid so that they are not influenced
structurally stable against tumble.
by ground vibration etc.
Measurement devices
AH measurement devices shall be inspected and
Table-5.1 Standard load step sequence
Number of steps
Number of cycles
Rate of loading
Not less than 8 steps
1 cycle or not less than 4 cycles
During loading. :
planned maximum load
number of steps
/min
During unloading : twice the rate used for loading stage
New loading steps
a constant period not less than 30 min
Holding time for each loading
Unloading or reloading steps a constant period not less than 2 min
step
Unloading to zero load
a constant period not less than 15 min
-3-
Table-5.2 Standard sampling periods and intervals
Data samplings are conducted at 0, 1, 2, 5, 10 and 15 min from the start of
New loading steps
load holding for each new loading step. Data samplings are repeated at 15
min intervals after the elplased time of 15min.
Data samplings are conducted at 0 and 2 min from the start of load holding
Unloading or reloading steps for each new unloading or reloading step, and at a time just before
proceeding the next step.
Data samplings are conducted at 0, 5 and 15 min. from the start of load
Unloading to zero load
holding at zero load. Data samplings are repeated at 15 min intervals after the
elplased time of 15rnin.
5. LOADING AND MEASURING METHODS
6. EXECUTION OF THE TEST
5.1 Loading methods
1) When the step loading method is adopted,
6.1
Testing personnel shall consist of a test supervisor, a
thestandard number of steps and cycles, the
loading operator, a record keeper and a safety manager.
rate of loading and the holding time for each
6.2
loading step are shown in Table-5.1.
2)
supervisor shall arrange all the personnel, and
an appropriate number of cycles shall be selected
shall manage the test overall in order to
according to the objectives of the test. Also the
accomplish the test objectives safely and properly.
shall
be
continuously
increased
2) The testing personnel shall ensure the safety of the
and
decreased with a constant rate of loading.
loading system and the normal functioning of the
Items to be measured
equipment prior to the commencement of the test.
3)
The following items shall be measured depending on
the test objectives:
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
5.3
1)
4) The record keeper shall measure the items at the
Time
Applied load
Displacements at the pile head
Displacements at the pile toe, the middle
part of the pile, and the loading point
Axial strains along the pile
Horizontal displacements at the pile head
Movements of the reaction devices
Others
established times. Also the principal records
should be arranged and graphed so that the state
of the test can be confirmed.
5)
to the safety of the test equipment and the area
6.3
1) The test shall be commenced after ensuring the
conditions surrounding the site, preparations of all
equipment, and the suitability of the weather
load step are shown in Table- 5.2.
condition.
When the continuous loading method is adopted,
2) If any abnormal conditions are noticed during the
the sampling periods and intervals shall be
test, the test shall be interrupted promptly. The
selected short enough to obtain a smooth
test can only be resumed when the cause of the
load-displacement curve. The load shall be
abnormal condition has been detected and
smoothly increased and/or decreased even during
remedied.
the measurements. All items shall be recorded in
3) The test shall be completed when the objectives of
a time so short that the measurements can be
having
been
Commencement, interruption and completion
of the test
When the step loading method is adopted, the
as
The safety manager shall pay sufficient attention
surrounding the test site.
Sampling periods and intervals
regarded
The loading operator shall operate the loading
devices correctly according to the plan.
standard sampling periods and intervals at each
2)
Tasks of the testing personnel
1) In accordance with the execution plan, the test
When the continuous loading method is adopted,
load
5.2
Testing personnel
the test have been achieved, or when it is judged
performed
that abnormal conditions make it impossible to
simultaneously.
-4-
6.4
continue the test.
follows; the S - log t method and the LiS /
Test record
log t - P method, the load at the specific point
The following items shall be recorded at the site:
(1)
at which the residual displacement increases
suddenly, and so on, where P is the load, S is
Dates and times of commencement,
interruption and completion of the test
(2)
(3)
Names of the testing personnel
Weather conditions
(4)
Arrangement and dimensions of the test
the displacement at the pile head, and t is the
elapsed time at a new load step.
(2)
the
system and the test pile
(5)
(6)
The second-limit-resistance shall be defined as
largest
load
measured
within
the
displacement of the pile toe less than 10% of
Photographs of the test equipment and the
test conditions
the pile toe diameter.
(3)
Special items (Situations, reasons and
countermeasures when the actual execution
The vertical stiffness at the pile head may be
obtained as the secant gradient of the
load-displacement curve at a prescribed design
differs from the initial plan, etc.)
load.
3)
7. TEST REPORT
Diagrams for the distributions of the axial strains
and the axial forces shall also be plotted when the
7.1
1)
Based on the collected data, the following
From the distribution curve of the axial forces, the
relationships shall be graphed:
following
values
can
be
estimated:
the
Load- Time relationship
characteristics of the frictional resistance of the
(2)
Displacement - Time relationship
pile surface in element of the shaft, and the
(3)
Load - Displacement relationship
characteristics of the resistance of the pile toe.
(4)
(5)
Load - Elastic Rebound relationships
Load - Residual Displacement relationships
(6)
Others
(1)
2)
axial strains along the pile shaft are measured.
Processing of the test results
7.2
Report
The report shall include the following items:
(1)
The purpose of the test
Based on the purpose of the test, the characteristic
(2)
The test site conditions, and soil profile
values of the vertical bearing capacity of the pile
(3)
The test procedure
shall be determined. The characteristic values of the
(4)
The pile dimensions and the test pile
installation method
vertical bearing capacity include the-first-limitthe
(5)
The test equipment
vertical stiffness at the pile head. They are
(6)
The loading and measuring methods
respectively defined by the following methods:
(7)
The test results
(1)
(8)
Others
resistance,
the-second-limit-resistance
and
The first-limit-resistance shall be defined as
Additionally, summary logs of nearby boreholes and a
the load at the point of maximum curvature
which appears clearly in the log P - log S
list of the soil testing results shall be attached to the
curve.
report.
The first-limit-resistance
shall be
synthetically judged by several methods as
-5-