The scope of Soil investigation
should be such as to clarify the soil conditions in order that satisfactory and
economical foundations can be designed and proposed recommendations for suitable
types of foundation and establishing the reliable soil parameter based on the
analysis of the geotechnical data.
These investigations should be
performed immediately after the Contract Award. The Contractor should submit
the investigations program to the Owner for approval. The program approval does
not relieve the Contractor from his obligation to undertake additional
investigations of the soil based on the Owner’s request, and that may be the
result of the soil investigation first report evaluation.
Investigation and elaboration of
reports on investigation results and structures foundations conditions should
be entrusted to an institution specialized for soil mechanics and foundation.
Such an institution and the Report should be approved of by the Owner.
The work shall include but not
limited to the mobilization and demobilization, transports and furnishing of
all machines, equipment and installations necessary to perform the works
specified hereafter, such as drilling rigs, rods, bits, casings, CPT, power
generators, compressors, pumps, vehicles, cisterns and all other matters deemed
necessary by the Contractor to perform the foreseen investigations as indicated
in Book II, "Summary of Work" and Book IIIA refers to "Civil and
Architectural Requirements".
CODES AND STANDARDS
The Contractor shall comply with
the requirements of Book II, "Codes and Standards".
The Codes and standards of the
following organizations extracted from Book II, "Codes and Standards"
are specifically applicable to the design, manufacture and testing of the work
included in this specification.
ASTM : American Society for
Testing and Materials
BS : British Standard
AASHTO : American Association of
State Highway and Transportation Officials.
WORKS EXECUTION
SCOPE OF INVESTIGATION
The following minimum of the
investigations program is compulsory:
a. 22 bore
holes on new site with total depth of 880 m
b. 15
static cone penetrations test on shore to the depth of 30 m in average.
c. In each
of the bore holes, undisturbed samples of soil shall be taken in 5.00 m
interval and minimum 1 (one) at each different layer, vane test and SPT test
shall be performed in 1.00 m interval.
d. Testing
laboratory for undisturbed and disturbed samples of soil properties.
CORE DRILLING
PROCEDURE
Core
drilling will be carried out by rotational method with clear water flush or on
the request of the Owner without any flush at all.
Core recovery is required on the
entire length of all drillings. A minimum core recovery of 90% is requested.
Only material not altered or damaged by the drilling process will be considered
as “core“. Zones where SPT, vane tests or undisturbed sampling performed are
considered as zones with recovered core.
Cores have to be handled
carefully in order to prevent deformation or breaking.
DEPTH
Drilling equipment must be able
to perform bore holes to a depth of 50 m.
The final depth of the bore
hole, as well as the depth achieved with every core run will be measured with
the drill rods in accuracy of 5 cm.
If a boring does not reach the
required depth, an additional hole has to be drilled and no compensation will
be given for the abandoned hole.
The Owner is entitled to change
the length of borings based on geological features.
DIAMETERS
The initial diameter shall have
to be chosen by the Contractor. The final core diameter should not be less than
54 mm.
In order to allow proper
telescoping, core barrels, bits and casing for several diameters should be on
the site.
OTHER OBLIGATIONS TO THE CONTRACTOR
The
Contractor shall assist the Owner during core logging and for all other works
related to the preparation and supervision of the Contractor's work.
The Contractor shall take
colored picture of all cores. Two copies 9 x 13 cm and the negative shall be
handed over to the Owner.
Each finished bore hole shall be
marked by a concrete block cast in place, with a minimum base dimension of 40 x
40 cm and a minimum height above ground surface of 10 cm. The number of the
bore holes has to be engraved in the concrete.
EQUIPMENT
Rigs shall meet the following
specifications :
- Hydraulic or mechanical feed : Transmission
gear to adjust spindle speed (e.g. 60 to 300 rpm).
The core barrels shall be in
perfect, which guarantee the request core recovery. The use of single tube core barrels is not allowed.
Diamond bits and hardened steel
bits in perfect condition from a well known manufacture shall be used.
The Contractor shall supply all
necessary flush water for the execution of boring and pertinent tests.
Facilities for sedimentation and water reservoir of adequate capacity may be
necessary. Only clear water shall be used.
The Contractor shall establish
the sequence of drilling and testing based on the frequent requirements for the
different bore hole tests to guarantee testing and sampling in natural soil
conditions and to allow for a reasonable drilling progress. The sequence shall
be approved by the Owner.
Core boxes should be made of
good and durable material and covered by a lid with hinges.
The inner length of a core box
shall be 1 m and for each meter of bore hole one meter of core box shall be
foreseen. The end of each core, as well as other pertinent information (e.g.
core loss, extracted sample, etc) has to be made immediately in the core boxes
with indication of actual depth.
Inscriptions on the boxes have
to be punched into aluminum or plastic straps.
The boxes must show the
following indications on the inside of the lid :
-
Job site
-
Number of bore hole
-
Date of finishing the bore hole
-
Number of the box
-
Depth interval
The boxes must show the
following indications on the outer small side :
-
Job site
-
Number of bore holes
-
Number of the boxes
Core boxes have to be stored in
such a way that they are protected against rain and sun.
STANDARD PENETRATION TEST (SPT)
The test shall be made according
to the following standards :
ASTM Designation D 1586 or BS
1377, Test 19.
The extracted sample shall be
packed and sealed in a plastic bag and placed in the core box. It shall be
labeled for identification with date, bore hole number, depth and number of
blows.
With the sampler resting on the
bottom of the hole, drive the sampler with blows from the 140 pound hammer
falling 75 cm until either 45 cm have been penetrated or refusal (defined as
100 blows per 15 cm or less of penetration) has been reached.
Standard reporting shall give
the number of blows for the first, second and third penetration of 15 cm. If
the number of blows for the first 15 cm would exceed 20, the penetration depth
for the first, second and third 20 blows shall be reported. Further more it
shall be reported if the hammer is free chopping or fixed by a rope
VANE TEST
The test shall be done according
to the standard ASTM D 2573, AASHTO T223, BS 1377,T18 or another standard
approved by the Owner.
To allow for calibration it
shall be performed just below the location of a SPT test.
The test shall be performed in
such a way that the rods are isolated from the soil, i.e. that no friction
occurs between the rods and the soil.
The maximum and residual value
of torque and corresponding shear strength shall be reported.
PERMEABILITY TEST
If there were any sandy layers
of the subsoil, the permeability shall be measured with the falling head test
method.
The test shall be performed
where such a layer is encountered or as directed by the Owner.
In general, not more than 2
tests shall be performed in one sand layer and no test shall be closer than 3 m
to the next one.
Before perform the test, the
bottom of the bore hole shall be cleaned and the water within the casing shall
be clear. The ground water level at the time of the test shall be registered.
For the test, the casing shall
be filled with clear water and the falling of the head in function of time shall
be measured. Registration time may be up to 20 minutes.
After the test, the depth of the
bore holes has to be controlled.
If the casing is telescoped,
special measures are needed to avoid water loss at the level of diameter
change.
The record of tests shall
include:
-
depth of boring
-
depth of ground water level
-
duration of test
-
diameter of casing at
depth of casing and water level measurements
-
array of data with time
and fall of water level during test.
The Contractor shall interpret
the data and give the permeability of the measured soil layer.
Data and interpretation shall be
handed over to the Owner on approved forms within 48 hours.
The compensation for test is
independent of the diameter of the depth below surface where the tests were
performed.
The supply of the required water
volume for flushing the hole and testing is understood to be part of the test
and the Contractor is not entitled to any additional payment irrespective of
the volume of water lost in preparation and performance of the test.
SAMPLING
In the course of the field
investigations, 3 types of samples shall distinguish:
All samples are taken from the
drillings. Within counting the SPT
samples, one sample shall be taken every in 1 m interval.
Undisturbed soil samples are extracted
from bore holes with a special instrument, as defined in ASTM D 1587, in fine
grained or cohesive soils.
The instrument is subject to the
Owner's approval.
Undisturbed soil samples shall
be taken in appropriate soils every 5 m interval or at regular intervals, as
directed by the Owner.
Disturbed samples shall be of
soil, taken from cores and packed and sealed in plastic bags or plastic tubes.
Number, type and size of these samples are directed by the Owner.
All samples shall be labeled.
The label shall indicate the project, site, bore hole, depth and date of
extraction.
On the site, the samples shall
be stored in a special place sheltered from sun and rain.
CONE PENETRATION TEST (CPT)
CPT equipment and testing
procedure shall be in accordance with the recommended standard, established by
the subcommittee on Standardization of Penetration Testing in Europe published
i.e. in the Conference Papers of ICSMFE. Tokyo 1977, vol.3, pg.95 ff.
Deviations from that standard
shall be indicated in the test report and need to be approved by the Owner.
Based on the actual geological
knowledge depth are envisaged for testing: 30 m.
The test results shall be
presented in a plot of cone resistance and total side friction versus depth.
Additionally, but not
alternatively the Contractor may offer the measurement of the pore water
pressure versus depth. In this case the Contractor shall submit a description
of this equipment and indicate the price for such readings per linear meter as
an over item to the price of CPT.
The test records shall be handed
over to the Owner within 48 hours after test performance.
They shall also be integrated in
the Final Report.
Such payment includes also the
set up of the test equipment at each location.
LABORATORY TESTING
The samples taken in the field
shall be transported to the laboratory at least every fortnight.
The Contractor is then
responsible for adequate storage, extraction, description and preparation of
each sample. All this work shall be included in the unit prices of tests and no
extra compensation is given for such work.
The Contractor will receive,
from the Owner, a test list indicating the tests to be performed for each
sample. If, for any reason, this test program can not be followed, the
Contractor shall immediately inform the Owner and furnish reasons.
The number of each test given is
the minimum requirement.
Variations from the given
quantities may be directed by the Owner.
For each test, the Contractor
shall indicate the standard he will follow.
Deviations from any standard or
the use of other standards than the ones specified hereafter need the written
approval of the Owner.
The following tests for soil
properties shall be performed in accordance with ASTM and/or AASHTO and/or BS
standards. Test and data recording shall include:
-
Particle size analysis of soil,
ASTM D422 or AASHTO T88 or BS1377.
-
Liquid limit of soil, ASTM D423 or
AASHTO T89 or BS 1377.
-
Natural water content, ASTM D2216
or BS 1377.
-
Natural (moist) unit weight, BS
1377.
-
Specific gravity, ASTM D854 or
AASHTO T100 or BS 1377.
-
Organic matter, ASTM C40 or ASTM
T21 or BS 1377.
-
Permeability, ASTM D2434
-
Unconfined compression strength,
ASTM D2166 or AASHTO T208 or BS 1377.
-
Consolidation, ASTM D2435 or AASHTO
T216 or BS 1377
-
Triaxial shear strength, AASHTO
T266 or BS 1377
-
Direct shear strength, AASHTO T236
REPORTS
DAILY REPORTS ON FIELD WORK
The driller will daily carry out
a report, containing:
-
Diameter and type of bit
-
Diameter and depth of casing
-
Rotation velocity
-
Drilling pressure
-
Total water losses
-
Pressure of clear water flush, color of flush
-
Depth and time interval of core runs
-
Types of soil
-
Water level in hole at beginning and at end of shift,
intermediate measurements
-
Any other pertinent information
The form of the daily report is
subject to the Owner's approval.
There is no extra compensation
for the daily reports.
FINAL REPORT ON FIELD WORK
The Final Report will obtain the
following items:
Activity time schedule of
investigation program (table)
Layout of the area where PLTU
Kalimantan Selatan (2 x 65 MW) is to be constructed, with structures locations
indicated, and the positions of investigations shall be carried out.
Drilling equipment used by the
Contractor on site (list)
Comments on the performed work.
Drawings of the bore logs.
Complete data and interpretation
for all field tests as SPT and permeability.
List of all extracted samples
(SPT, disturbed and undisturbed ) Logs of CPT.
DRAFT
REPORT.
A draft of the Final Report is
subject to the Owner's approval. It shall be. delivered not later than 1 week
after termination of the field work.
PROGRESS REPORT OF LABORATORY WORK.
Every two weeks, the Contractor
shall prepare and forward to the Owner one report with the following features :
-
Samples received
-
Tests performed
-
Deviation from the test program
-
Comments on the test program and on the test result
-
An annex containing all test results of the given period
No extra compensation is
foreseen for the Progress Reports.
TEST RECORD
All
forms for the test readings and interpretations shall be approved in advance by
the Owner. The Owner may also require additional forms or different plots.
FINAL REPORT ON LABORATORY WORK
The final report shall contain
the following items:
-
a sample list
-
a list of performed tests
-
Summaries of test results, arranged according to
technical, geological or geotechnical
features
-
all test results, readings, plots and interpretations.
The Contractor shall first
prepare a draft issue of the Final Report and submit it to the Owner for
approval. It shall be delivered not later than 4 weeks after termination of the
field works.
All forms and reports shall be
in English.
The Contractor shall hand over 5
copies of the Final Reports to the Owner. Furthermore shall provide to the
Owner, the original of all text and data sheets and a transparent copy of all
drawings.
The lump sums for reporting
shall include all data collections, typing, copying, interpretation,
calculation, designing, drawings, reproducing, posting, as well as all paper and
other material and work necessary, to provide the required and approved
reports.
The contract work is regarded to
be terminated after the Owner has accepted in writing, the draft of the Final
Reports and after the Contractor has delivered all originals and copies of the
Final Reports in correspondence with the accepted Draft Reports, as specified
above.