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DRILLED SHAFT INSPECTORS GUIDELINE
GEOTECHNICAL ENGINEERING MANUAL
GEM-18
Revision #2
AUGUST 2015
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EB 15-025 Page 1 of 30
GEOTECHNICAL ENGINEERING MANUAL:
DRILLED SHAFT INSPECTORS GUIDELINES
GEM-18
Revision #2
STATE OF NEW YORK
DEPARTMENT OF TRANSPORTATION
GEOTECHNICAL ENGINEERING BUREAU
AUGUST 2015
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EB 15-025 Page 2 of 30
TABLE OF CONTENTS
1. INTRODUCTION................................................................................................................3
1.1 Purpose .....................................................................................................................3
1.2 Role and Responsibilities of the Inspector ...............................................................3
1.3 Definition of Terms..................................................................................................4
2. CONTRACT REQUIREMENTS ........................................................................................6
2.1 Specifications ...........................................................................................................6
2.2 Plans .........................................................................................................................6
3. PRECONSTRUCTION MEETING ....................................................................................7
4. DRILLING ...........................................................................................................................9
5. CONCRETING ..................................................................................................................10
6. INTEGRITY TESTING .....................................................................................................12
7. CONSTRUCTION MONITORING ..................................................................................15
7.1 Monitoring Aids .....................................................................................................15
7.2 Guidelines for Filling Out Drilled Shaft Monitoring Forms ..................................20
7.2.1 Drilled Shaft In Rock - Field Record Page 1 .............................................20
7.2.2 Drilled Shaft In Soil - Field Record Page 1 ...............................................25
7.2.3 Drilled Shaft In Rock or Soil - Field Record Page 2..................................25
REFERENCES ..............................................................................................................................29
APPENDIX ....................................................................................................................................30
A Drilled Shaft In Rock - Field Record Page 1 ...................................................... A-1
B Drilled Shaft In Soil - Field Record Page 1 ......................................................... B-1
C Drilled Shaft In Rock or Soil - Field Record Page 2............................................C-1
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1. INTRODUCTION
1.1 Purpose
These guidelines along with the Drilled Shaft Inspectors Manual, prepared by ADSC: The
International Association of Foundation Drilling and DFI: Deep Foundation Institute, providesthe inspector or Engineer-In-Charge (EIC) with a working knowledge of drilled shaft
construction techniques. To become familiar with drilled shaft installation techniques, a working
knowledge of the tools used by contractors is also essential. The Drilled Shaft Inspectors
Manual will provide the individual with a working knowledge of drilled shaft installation
equipment in addition to familiarity with actual construction techniques. Lastly, these guidelines
will provide the individual with monitoring aids to facilitate the inspection procedures and
enhance the transfer of information from the inspector to the designer. The monitoring aids
consist of methods to obtain necessary field data as well as inspection forms on which to record
this data.
There is no substitute for direct contact between the inspector and the geotechnical engineer whodesigned the drilled shaft foundation. Contact with the geotechnical engineer will give the
inspector access to information he/she may not have possessed otherwise, as well as insight into
why drilled shafts were utilized on this project. The geotechnical engineer will be responsible for
reviewing the construction information recorded by the inspector, as well as, evaluating the
foundation for acceptability. For this reason alone, it is prudent that the inspector/EIC and the
geotechnical engineer have a good working relationship. At the very least, the geotechnical
engineer should sit down with the inspector/EIC before construction begins and discuss any
concerns either have.
1.2 Role and Responsibilities of the Inspector
The primary role of the inspector is to make sure that construction is done in accordance with the
plans and specifications contained on the project. Thus it is imperative that the inspector is
familiar with the plans and specifications of the project. Any deviation from the plans or
specifications should be promptly noted and reported to the proper authorities, who will
determine what actions to take.
The inspectors secondary function is to record and transmit information. The drilled shaft
inspector is there to observe and document the contractors installation of the drilled shaft. In
this regard he/she should also try to be as complete and as concise as possible when recording
and transmitting this information to the proper authorities. The quality of this information mustbe very high as it will be used to make important decisions such as the approval or rejection of
the drilled shaft.
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1.3 Definition of Terms
Casing Method - A method of shaft construction, consisting of advancing and cleaning a
cased hole, placing the reinforcing cage, and concreting the shaft while
extracting temporary casing (if used).
Casing (Shell) - A steel shell used to construct the drilled shaft. The casing can help
advance the hole, and supports the sides of the hole. Casing may be
permanent or temporary.
Drilling Mud - A slurry made using bentonite or polymers (see Slurry).
Drilled Shaft - A cylindrical structural column transmitting loads to soil and/or rock. The
drilled shaft is constructed in a hole with a circular cross section. The hole
is filled with concrete and may be reinforced with steel.
Dry Construction A method of shaft construction consisting of drilling the shaft, removingMethod - the water and material from the excavation, placing the reinforcing cage,
and concreting the shaft in a relatively dry condition.
Permanent Casing - A casing that acts as a form, but remains in place permanently. It is
usually not designed to carry structural loads.
Quality Assurance - A test or procedure that acts to verify the quality of the work or product.
Quality Assurance procedures would include static load testing, Osterberg
Cell testing, coring, cross hole sonic logging, and other non-destructive
testing.
Rock - Rock is identified in the boring logs. Rock may also be defined at the shaft
installation site by a Departmental Engineering Geologist. Keep in mind
that the state defines rock by its load bearing capacity and often, the
contractor will define rock by the effort or tools required to progress the
excavation through the material. These conflicting criteria will often result
in different definitions of rock at a site. Refer to the Contract Plans for
guidance on how rock is defined for the project.
Seat - The act of placing the tip of a casing in intimate contact on rock for its
entire circumference.
Slurry - A mixture of water and bentonite, or water and polymers, which provides
hydrostatic pressure that supports the sides and bottom of the hole,
lubricates and cools the drill tools, and aids clean out. Slurry cannot be
made from native materials, or material from the excavation.
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Sound Rock - Competent, massive, and unweathered rock, typically with a Rock Quality
Designation (RQD) of at least 70%. Elevation of sound rock is always
determined by a Departmental Engineering Geologist. Be aware that
sound rock is not always required for a drilled shaft rock socket.
Surface Casing - Temporary casing installed to prevent sloughing of the surrounding soilnear the surface of the shaft excavation.
Temporary Casing - A casing that serves its function during construction of the drilled shafts. It
serves no permanent structural function, and is extracted during
concreting.
Top of Socket - The highest location of the rock socket that is capable of resisting axial
and lateral design loads. At any given location, the top of socket elevation
is usually below the top of rock elevation. This distance depends on the
type and quality of rock, and the Contractors drilling methods and
equipment.
Tremie - A method to place concrete under water. Refer to Section 555 - Structural
Concrete of the NYSDOT Standard Specifications.
Trial Shaft - A hole for a drilled shaft constructed on the project site, but outside the
proposed footing limits. It is not to be incorporated into a structure or
foundation. A trial shaft is constructed prior to installing production drilled
shafts, according to the methods detailed in the Contractors submittals. Its
function is to verify the proposed excavation methods, and permit the
Inspectors to become familiar with the excavation procedure. Upon
inspection and acceptance, the trial shaft is backfilled with unreinforcedconcrete.
Wet A method of shaft construction consisting of using slurry to maintain
Construction stability of the hole while advancing the excavation to the final depth,
Method - placing the reinforcing cage, and concreting the shaft.
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2. CONTRACT REQUIREMENTS
2.1 Specifications
The inspector should be familiar with the drilled shaft specification. The specification contains
the following information that will be essential for the inspector to consult during construction:
Construction Tolerances - The specification contains all the allowable shaft tolerances, such as
location, verticality (plumbness), cutoff elevation, rebar stick up, and diameter. Failing to meet
these tolerances will result in a rejected shaft.
Drilling and Excavation Methods - The specification contains the allowable procedures for the
different shaft drilling methods. They also provide the requirements of each procedure. The
contractor must adhere to these requirements or once again the shaft could be rejected.
Rebar, Concrete Placement, and Temporary Casing Removal - The specification contains the
allowable procedures and requirements for the above operations. Again, the contractor mustadhere to these requirements or risk rejection of the shaft.
The specification also contains additional miscellaneous information on shaft requirements that
the inspector should become familiar with. A good working knowledge of the specification is
essential in proper drilled shaft construction monitoring.
2.2 Plans
The contract plans are another important source of information for the inspector. The contract
plans contain all of the specific requirements of that particular project as opposed to the
specification which covers only general requirements. The specifications refer to the contract
plans many times (for example: ....as shown on the contract plans....). The plans also refer back to
the specification for direction where applicable (for example: ....as per Item xxx.xx...). The
inspector should be familiar with the contract plans and know where to find information in them.
The contract plans contain the actual shaft design and any and all requirements not covered in the
specification. These requirements are what the contractor bid on, and what he/she must construct.
Any unauthorized deviation from the contract plans should be reported immediately through the
proper channels.
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EB 15-025 Page 7 of 30
3. PRECONSTRUCTION MEETING
Since the acceptance or rejection of a drilled shaft is usually based solely on results of integrity
tests and inspection records of the shafts installation, a preconstruction meeting is essential. This
meeting will be in addition to the usual preconstruction meeting which is standard on all DOT
projects. The primary focus of this meeting is to go over the contractors submittals to determineif there are any concerns. This meeting should be between the Engineer-In-Charge (EIC), the
inspector(s), the Regional Geotechnical Engineer, and the designer of the shaft.
This meeting will allow the EIC and his inspector and the design engineer to go over the
contractors submittals to see if there are any concerns on either side. It will also alert the
inspector as to what aspects of the construction submittal could potentially affect the
performance of the shaft. The designer should have reviewed (and commented back to the
contractor, if necessary) these submittals prior to the meeting. As per the current drilled shaft
specification, here is what the contractor must submit to the designer before construction can
begin:
a. Method describing how the Contractor will progress through obstructions and rock.
b. Details and method describing how the Contractor will keep the hole for the drilled shaft
open.
c. Drawings showing and details describing the proposed sequence of drilled shaft
installation. Include the sequence for each shaft, the overall construction sequence, and
the sequence of shaft construction in bents or groups.
d. Information describing the type of equipment to be used, including drill rig, cranes,
drilling tools, final cleaning equipment, desanding equipment, slurry pumps, sampling
equipment, tremies or concrete pumps, casing(including: casing dimensions, material and
splice details), etc.
e. Proposed method for cleaning out the shaft excavations. Include a description of how the
Contractor will perform spoil removal and disposal.
f. Information that shows that the Contractor, Driller, and Foreman meet the pre-
qualification requirements stated previously. Include the name and telephone number of
someone for each project cited who can be contacted as a reference.
g. Shaft excavation methods, and final shaft dimensions.
h. If slurry is to be used, indicate the method proposed to mix, circulate, and desand slurry.
Include methods of slurry disposal in the submittal.
i. Method of reinforcement placement, including support and centralization type and
methods.
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j. Details and method of concrete placement, curing, and protection.
k. If the concrete mix is modified (i.e., retarders), include the new mix design, and test
results of cylinder breaks from an independent laboratory. Also, include test results that
demonstrate a slump loss versus time relationship.
l. A description and details of the slurry sampling tool to be used. Provide a tool capable of
taking a slurry sample at a specific depth, without being contaminated by slurry from
another depth.
m. When slurry is used, include an alternate procedure to be used which will secure the shaft
in the event of slurry loss.
n. A description of the type of feet to be used to support the rebar cage in the drilled shaft.
o. An emergency construction joint procedure, to be used in the event when concrete
placement for the drilled shaft is unexpectedly interrupted.
p. A procedure for filling voids between permanent casing and the soil.
q. A description of equipment and methods to be used for drilled shaft inspection. The
Inspector will use these methods and equipment to inspect the drilled shafts. The
inspection program must be thorough enough to assure the Department that each drilled
shaft meets the requirements contained in this specification.
Each one of these items should be gone over in detail, so that all concerned parties will know
what to except and what to look for during construction. Deviation from the approved submittals
by the contractor must not be tolerated, and will result in rejection of the shaft. Depending on thedesign, different portions of these submittals will be critical. The designer should make the
inspector aware of which operations/equipment are crucial for the acceptance of the shaft.
The meeting will also open the channels of communication between the EIC and the designer.
This too is essential as information (such as the inspection forms and integrity test reports) will
be transmitted from the EIC to the designer for approval. Also in the case of problems during
construction, a solution can be more easily achieved if everyone is on the same page.
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4. DRILLING
Most drilled shaft excavations are done using rotary drilling machines. These machines come in
many different sizes and designs. The capacity of a drill rig is expressed in terms of the
maximum torque that can be applied to the drilling tool, as well as the downward force, or
crowd, that the rig can apply to the drilling tool. Torque and crowd are transmitted from therig to the drilling tool by a shaft of steel, known as a Kelly bar. Most Kelly bars are square in
cross section, but do not have to be. Kelly bars start off as a set length but can be telescoped to
drill at greater depths. The Kelly bar passes through a rotary table that is turned by a power unit.
Drill rigs can be mounted on trucks, cranes, or crawlers.
Refer to Chapter 3 of the Drilled Shaft Inspectors Manual for in-depth information on drilling
tools, techniques, and what to be looking for during inspection of the drilling procedure.
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EB 15-025 Page 10 of 30
5. CONCRETING
Concrete for drilled shafts must be designed and placed in a manner that is unique to drilled
shafts. The basic characteristics of concrete for drilled shafts are (from Drilled Shafts:
Construction Procedures and Design Methods):
Excellent Workability - It is essential that the concrete have the ability to flow readily
through the tremie, to flow laterally through the rebar cage, and to impose a high lateral
stress against the sides of the borehole. From a geotechnical perspective, the objective of
placing concrete is to reestablish the lateral stresses in the ground around the drilled shaft
that existed before the borehole was excavated. This objective can best be met by using
concrete that is highly fluid.
Self-Weight Compaction - Vibration of concrete in a borehole is impractical, except very
near the surface. In some cases this will lead to defects in the completed shaft by causing
ground water, drilling fluid, or soil to mix with the concrete.
Resistance to Segregation - The concrete mix should have a high degree of cohesion and
should be free of large-sized aggregate; otherwise, it may segregate during placement,
particularly if free fall is allowed, resulting in inferior concrete.
Resistance to Leaching - In some instances flowing ground water could cause a
weakening of the concrete after it is placed. A properly designed mix should be resistant
to such flow. However, if the rate of flow is substantial, a permanent casing or liner will
be necessary. Furthermore, when concrete is placed under a drilling fluid (slurry or
water), there is inevitable contact between the concrete and the fluid, which is a condition
that also requires the mix to be resistant to leaching.
Controlled Setting - Drilled shaft concrete should retain its fluidity throughout the depth
of the borehole during the full time required for complete placement of the concrete in the
borehole to maximize the lateral pressures that are imposed by the fluid concrete. Slow
setting is also required to allow for inevitable delays that may occur during concreting,
such as: interrupted concrete supply, difficulties in extracting casing, etc. At the same
time, it should attain an appropriate strength within a reasonable time after placement.
Good Durability - If the subsurface environment is potentially corrosive or can become
corrosive during the life of the foundation, the concrete should be designed to have high
density and low permeability so that the concrete is able to resist the negative effects ofthe environment.
Appropriate Strength and Stiffness - The size of most drilled shafts will be controlled by
the peripheral area and base area that are needed to develop the required axial load
resistance. Therefore, high-performance concrete is usually not needed. The mechanical
properties of the hardened concrete can be satisfied in such instances without difficulty.
However, provision of appropriate compressive strength where high levels of combined
bending and axial stress occur must be dealt with in some cases.
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Low Heat of Hydration for Large Volumes of Concrete - Careful attention must be given
to the design of concrete for bells and for large-diameter drilled shafts so that excessive
heat does not produce thermal tensile cracking.
Refer to Chapter 4 of the Drilled Shaft Inspectors Manual for in-depth information on concreteplacement techniques and what to be looking for during inspection of the concreting procedure.
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6. INTEGRITY TESTING
The most common types of integrity tests performed on completed drilled shafts are the
following:
Sonic Echo Test
This test consists of striking the head of the drill shaft with a hand-held hammer. A sonic wave is
generated that travels down the shaft, is reflected from the shaft base or from a defect in the shaft,
and is picked up by an accelerometer. This is a very crude test which can only detect major
defects such as a major soil inclusion or bases of shafts that were drilled to the wrong depth.
Impulse-Response Test
This test is similar to Sonic-Echo testing except that a more sophisticated method of processing
the data is used. In addition to recording the motion at the head of the shaft versus time, the
force applied by the hammer is also recorded versus time. The same limitations that apply toSonic Echo testing apply to Impulse-Response testing, but the data is usually easier to interpret.
Impedance Log
Further computer processing of data from a Sonic Echo/Impulse-Response test can be performed
to produce a graph of the cross-sectional area of the shaft as a function of depth. The result of
this processing is an impedance log, which will provide a clear indication of average shaft
diameter versus depth. Impedance Log testing has the same general limitations of the previous
two tests, but is less prone to false positive results.
Parallel Seismic Test
A water filled tube is installed parallel to the shaft, then a piezo-electric receiver is lowered down
the tube, and lastly, the shaft is struck with a hand-held hammer. The receiver can be moved up
and down the tube to test the shaft at any point. The shaft does not have to be struck on its top, so
the test is useful when the top of a shaft is not accessible. A change in arrival rate from the
hammer blow indicates the presence of a major defect. The base of the shaft can also be
determined in this way. As with the previous small-strain tests, small defects are not likely to be
detected.
Internal Stress Wave Test
This test is the same concept as Sonic Echo, except that the receivers are embedded in the shaft
at varying depths. This test will give clearer results as the noise level is much reduced when
compared to Sonic Echo testing. The test has the same general limitations as Sonic Echo testing,
and since the receivers are embedded in the shaft, the decision to use the test must be made
before construction.
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EB 15-025 Page 13 of 30
Crosshole Acoustic (Sonic and Ultrasonic) Test
Crosshole Acoustic testing or Crosshole Sonic Log testing consists of installing several metal or
plastic tubes attached to the rebar cage of the drilled shaft. The tubes have sufficient diameter to
admit probes and are filled with water (to better transmit energy from the wall of the tube to the
probe). To perform the test, an acoustic transmitter is lowered into one of the fluid filled tubes,and a receiver is lowered to the same depth, in another tube. The transmitter emits an acoustic
signal which is picked up by the receiver. The test is repeated at many depths along the entire
length of the shaft. The travel time of the signal is measured. If there is a defect in the shaft, the
travel time increases. By testing all combinations of tubes, a defect, its magnitude, and its
location in the shaft can be mapped out. The two limitations of the test are that the access tubes
are installed during construction of the shaft, so the decision to use the test must be made before
construction, and the test cannot detect defects outside of the rebar cage, as only concrete
between tubes can be tested.
Gamma-Gamma Testing
As with Crosshole Sonic Log testing, access tubes are installed in the shaft during construction.
A source of ionizing radiation is lowered down the tubes. The tubes cannot be made of steel as
this would prevent the gamma rays from penetrating the concrete. The instrument containing the
radioactive source also contains a gamma ray detector. The gamma rays emitted are reflected
back by the surrounding concrete. The reflected gamma ray count per unit time is calibrated to
the concrete density. If the density measured falls below the expected density of normal concrete,
a defect in the concrete is indicated. The access tubes must be installed during construction of the
shaft, so the decision to use the test must be made in design. The only other limitation of the test
is that the area of concrete tested is relatively small, no more than 4 in. (100 mm) from the edge
of the access tube. So even with several access tubes, most of the concrete area of a shaft cannot
be tested. Note that the area outside of the rebar can however, be tested with this method.
Coring
If a shaft is suspected of having a major defect, it can be cored and the concrete sampled along its
entire length. Coring is expensive and time consuming. Since the area cored is small when
compared to the shaft area, small defects will not be detected.
New York State DOT Practice
The New York State DOT practice is to specify Crosshole Sonic Log testing on all production
drilled shafts. If the testing indicates a major defect, the shaft is then cored at various locations to
determine the nature and extent of the defect.
As Crosshole Sonic Log testing is our primary method of determining a shafts integrity, the
inspector should pay close attention to the installation of the access tubes. The tubes should be
undamaged and should comply with our specifications. They should be attached to the rebar cage
securely at the designed locations. During lowering of the rebar cage into the hole, care should be
taken to avoid damage to the tubes (such as crushing them against the sides of the shaft or
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bending them at the bottom). Access tubes that are not attached correctly or damaged during
installation will often result in the testing indicating a defect in the concrete when there is none.
Keep in mind that the test assumes a constant distance between access tubes. If these distances
change due to improper installation or damage, the distance between tubes will vary. This will
result in a different wave speed through the concrete at different depths. This differing wavespeed will be interpreted as a defect in the shaft, resulting in the subsequent expensive and time
consuming coring of the shaft.
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7. CONSTRUCTION MONITORING
7.1 Monitoring Aids
The next four pages provide the following drilled shaft construction monitoring aids:
1) Suggested Method to Check Shaft Plumbness if Horizontal Tolerance is Known - describes a
quick procedure to determine if the shaft is out of plumb (required verticality). As specified
in the specification the allowable tolerance from the required verticality is 2% for vertical
shafts, 3% for battered shafts. This procedure assumes that the actual tolerance for the shaft
has been computed, based on the allowable tolerance from the required verticality (either 2%
or 3%) and the total shaft length. This test should be performed when the shaft excavation is
completed.
2) Suggested Method to Check Shaft Plumbness - describes a procedure to determine a shafts
plumbness at any point during construction. It is essentially the same procedure as above. The
figure shows three measurements for each check. Keep in mind that if the casing iscontinuous (i.e. one piece) or no casing is used, only one measurement is required for a
plumbness check. This procedure should be performed periodically as the shaft is progressed
to maintain correct shaft verticality.
3) Suggested Method to Check Concrete Level - describes a procedure to determine the concrete
level during pouring. Determining the correct concrete level during the pour is essential for
the completion of the concrete curve (a key part of the inspection forms). Basically a tape
measure with its end attached to something that will sink in water and other drilling fluids,
but will float on the wet concrete is used for this procedure. This will allow the inspector to
determine the level of concrete in the shaft at any point during the pour, even if the shaft is
filled with water or drilling fluid.
4) Shaft Areas and Volumes Table - Is a self explanatory table that aids the inspector in
determining the shafts volume.
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Shaft Areas and Volumes
Per Linear Foot Per Linear Meter
Shaft
Diameter
(in.)
Volume
(yd3)
Side Shear
Area
(ft2)
Bearing
Area
(ft2)
Shaft
Diameter
(cm)
Volume
(m3)
Side Shear
Area
(m2)
Bearing
Area
(m2)
12 0.03 3.14 0.79 30 0.07 0.94 0.07
14 0.04 3.67 1.07 35 0.10 1.10 0.10
16 0.05 4.19 1.40 40 0.13 1.26 0.13
18 0.07 4.71 1.77 45 0.16 1.41 0.16
20 0.08 5.24 2.18 50 0.20 1.57 0.20
22 0.10 5.76 2.64 55 0.24 1.73 0.24
24 0.12 6.28 3.14 60 0.28 1.88 0.28
26 0.14 6.81 3.69 65 0.33 2.04 0.33
28 0.16 7.33 4.28 70 0.38 2.20 0.38
30 0.18 7.85 4.91 75 0.44 2.36 0.44
32 0.21 8.38 5.59 80 0.50 2.51 0.50
34 0.23 8.90 6.31 85 0.57 2.67 0.57
36 0.26 9.42 7.07 90 0.64 2.83 0.6438 0.29 9.95 7.88 95 0.71 2.98 0.71
40 0.32 10.47 8.73 100 0.79 3.14 0.79
42 0.36 11.00 9.62 105 0.87 3.30 0.87
44 0.39 11.52 10.56 110 0.95 3.46 0.95
46 0.43 12.04 11.54 115 1.04 3.61 1.04
48 0.47 12.57 12.57 120 1.13 3.77 1.13
50 0.51 13.09 13.64 125 1.23 3.93 1.23
52 0.55 13.61 14.75 130 1.33 4.08 1.33
54 0.59 14.14 15.90 135 1.43 4.24 1.43
56 0.63 14.66 17.10 140 1.54 4.40 1.54
58 0.68 15.18 18.35 145 1.65 4.56 1.65
60 0.73 15.71 19.63 150 1.77 4.71 1.7762 0.78 16.23 20.97 155 1.89 4.87 1.89
64 0.83 16.76 22.34 160 2.01 5.03 2.01
66 0.88 17.28 23.76 165 2.14 5.18 2.14
68 0.93 17.80 25.22 170 2.27 5.34 2.27
70 0.99 18.33 26.73 175 2.41 5.50 2.41
72 1.05 18.85 28.27 180 2.54 5.65 2.54
74 1.11 19.37 29.87 185 2.69 5.81 2.69
76 1.17 19.90 31.50 190 2.84 5.97 2.84
78 1.23 20.42 33.18 195 2.99 6.13 2.99
84 1.43 21.99 38.48 210 3.46 6.60 3.46
90 1.64 23.56 44.18 225 3.98 7.07 3.98
96 1.86 25.13 50.27 240 4.52 7.54 4.52
102 2.10 26.70 56.75 255 5.11 8.01 5.11108 2.36 28.27 63.62 270 5.73 8.48 5.73
114 2.63 29.85 70.88 285 6.38 8.95 6.38
120 2.91 31.42 78.54 300 7.07 9.42 7.07
126 3.21 32.99 86.59 315 7.79 9.90 7.79
132 3.52 34.56 95.03 330 8.55 10.37 8.5
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7.2 Guidelines for Filling Out Drilled Shaft Monitoring Forms
7.2.1 DRILLED SHAFT IN ROCK- FIELD RECORD Page 1
TITLE BLOCK/JOB STAMP
Project Stamp- This area should contain the Project Stamp. The Project Stamp
contains the project name, the PIN, the BIN, the Contract Number, the
town or city, and the county.
Structure- Structure refers to the specific substructure this particular shaft willsupport. For example: Bridge 2, North Abutment.
Shaft Number- The shafts number as designated in the Contract Plans.
Date- Date form was initiated.
GENERAL SHAFT INFORMATION
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Date Excavation- The date and the time the shaft was begun. Preliminary work such as
Started staking out the shafts location does not constitute the beginning of the
shaft. Installing a temporary surface casing or actual drilling usually
constitutes the beginning of a shaft.
Date Bottom - The date when the bottom of the shaft was cleaned out and checked,Cleaned usually right before the concrete is poured.
Date Concrete - The date and the time the shaft was concreted.
Placed
DESIGN- The appropriate value as it appears in the Contract Plans.
AS-BUILT- The appropriate value as it was installed in the field.
Station- The center of the shafts station as referenced to a specified station
line.
Offset- The center of the shafts offset from the station line.
Top Elevation- The top elevation of the shaft as referenced in the Contract Plans. By
this we mean however the top of the shaft is defined in the Contract
Plans is the way it should be defined in the field. For example if the
Contract Plans define the top of the shaft as the top of a permanent
casing, it should be defined in the field as such, not by some other
means, such as the top of a temporary casing.
Bottom - The bottom elevation of the shaft as referenced in the Contract Plans
Elevation (see Top Elevation).
Shaft Diameter - Diameter of the shaft, not including temporary casings.
Shaft Length- Total length of shaft from defined top elevation to defined bottom
elevation.
Rock Socket - The diameter of the rock socket (if applicable). The rock socket is
Diameter typically smaller (usually 6 in. (150 mm)) than the overall shaft
diameter.
Rock Socket - The length of the socket measured from the top of sound rock to the
Length bottom of the shaft.
Plumbness- The overall plumbness of the shaft. This should be calculated using a
plumb bob as described in the manual (Suggested Method to Check
Shaft Plumbness).
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EB 15-025 Page 22 of 30
Design Capacity- This is copied right from the Contract Plans. It is on the form as a
reference for the inspector.
Observed - This is the observed groundwater elevation in the shaft during drilling.
Groundwater
Elevation
Remarks- Any remarks the inspector wishes to make should be placed here.
SHAFT SCHEMATIC (Casing Information)
OGS Elevation- The original ground surface elevation at the shaft site prior to drilling.
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Top of Rock - The elevation of the top of the rock socket as determined by the plans.
Socket Elev. Keep in mind that this is not necessarily the top of rock elevation.
Shaft Bottom - The bottom of the shaft as measured in the field (the same as the table
Elev. entry As-Built Bottom Elevation).
Surface Casing- A temporary casing used to start the hole. It is usually only a few feet
or meters deep.
Permanent or - If a casing is used, circle which type. This casing is used to progress
Temporary the shaft through the soils.
Casing
Top Elev.- The top elevation of the casing in question. This should be referenced
to the top of the shaft elevation.
Bottom Elev. The bottom elevation of the casing in question. Again referenced to thetop of the shaft elevation.
Length - Length of casing, top to bottom elevation.
Thickness- Thickness of casing.
O.D. - Outside diameter of casing.
DR- Diameter of rock socket (same as As-Built Rock Socket Diameter).
LR- Length of rock socket (same as As-Built Rock Socket Length).
Plumbness - By using the Suggested Method to Check Shaft Plumbness with a
Measurements plumb bob you would get an average horizontal distance from the
plumb bob to the reference edge of the casing, this distance would be
X. The distance from the top elevation of the shaft to the plumb bob
would be Y. Using these measurements you can calculate the
plumbness and enter it in the General Shaft Information Table.
Alternatively, if you calculated the horizontal distance tolerance using
the specifications, your X would be this tolerance while your Y
would have to be the entire shaft length for the shaft to be withinhorizontal tolerance (refer to section of the manual entitled Suggested
Method to Check Shaft Plumbness if Horizontal Tolerance is
Known).
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EB 15-025 Page 24 of 30
DRILLING INFORMATION
Date and Time - Date and time specific strata was drilled through.
Depth- Depth measured from the top of OGS to the top of the strata
documented in this entry.
Soil or Rock - The NYS Geotechnical Engineering Bureau soil/rock description for
Description the strata encountered (refer to STP-2 - An Engineering Description of
Soils Visual-Manual Procedure). For example: Silty SAND,
LIMESTONE, Sandy GRAVEL, etc. It is especially important to noteunexpected soil types and problematic soil types (such as clays,
organics, or miscellaneous fills).
Tool- The tool used to progress the shaft through the material being noted
(i.e. auger, muck bucket, core barrel, etc.).
Observations - Any unexpected occurrences, such as encountering obstructions,
breakdowns of the rig, loss of water or drilling fluids, or caving of the
hole should be noted with as much detail as possible. This can aid in
evaluating the shaftafter installation.
CONTRACTOR/ENGINEER RECORD
General Contractor- The General Contractor of the project.
Drilling Contractor- The drilling subcontractor who actually installs the drilled shaft.
Engineer-in-Charge- The EIC of the project.
Inspector - The construction inspector filling out these forms.
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EB 15-025 Page 25 of 30
7.2.2 DRILLED SHAFT IN SOIL- FIELD RECORD Page 1
This form is filled out identically to the Drilled Shaft in Rock - Field Record Page 1. Instead
of rock socket information entries this form contains the following bell information entries:
Bell Diameter- The diameter of the bell as appears on the plans for the Design entryand as installed for the As-Built entry.
Bell Height- The height of the bell, as designed and as installed. Bell height should
also be labeled on the schematic in its appropriate space.
7.2.3 DRILLED SHAFT IN ROCK OR SOIL- FIELD RECORD Page 2
CONCRETE PLACEMENT INFORMATION
Concrete - The general method by which the concrete is placed into the drilled
Placement shaft. Three methods are listed: Air - pouring or dropping concrete
Techniques directly into shaft, no water can be present in shaft; Tremie - placement
of concrete under water, either poured or pumped; Pump - concrete is
pumped into drilled shaft. When concrete is tremie pumped into shaft,
both the tremie and the pump boxes should be checked.
Type of Priming- Describes the specific method by which the concrete is transported
Plug from the mixer to the shaft.
CONCRETING CURVE
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This section contains space for a concrete curve. This allows the inspector to compare
theoretical shaft concrete volume with actual measured shaft concrete volume. Using the
Shaft Volume chart contained in the manual, the inspector should first graph the theoretical
concrete volume curve on the chart. This curve represents the volume of concrete by depth if
the shaft were installed perfectly (concrete volume equals theoretical shaft volume). As the
concrete is being poured the inspector should carefully keep track of the poured volume. Thelevel of concrete can be measured using the Suggested Method to Check Concrete Level
contained in Section 7 of these guidelines. The actual measured concrete volume should then
be placed on the chart. Comparing the two curves will tell the inspector if concrete was lost
or gained. Lost concrete would be obvious as the measured concrete volume curve would be
greater than the theoretical concrete volume curve. Concrete gain caused by soil squeezing or
hole collapse would also be obvious as the measured volume would be less than the
theoretical volume. Gains and losses from soil caving could also be detected (soil caving
would at first lower the measured volume by displacing concrete with soil, then increase the
measured volume as the concrete level gets to the area of the shaft that caved).
SHAFT CROSS SECTION SKETCH
This section allows the inspector to document the shaft reinforcement and any integrity test
access tubes that were incorporated into the shaft. The cross section of the shaft should be
sketched in by the inspector. The cross section should show any reinforcement as it is placed.
The position of integrity test access tubes is especially important, as it would be useful in
evaluating the tests later, and they should be noted carefully.
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REINFORCEMENT PROFILE
Rebar Cage Information
Bar Size - The size designation of the rebar in the cage.
Number of Bars- The total number of bars in the cage.
Top Elev.- The top elevation of the rebar cage in question.
Bottom Elev.- The bottom elevation of the cage in question.
Cage Diameter - The outside diameter of the rebar cage.
(O.D.)
Integrity Testing Access Tubes Information
Tube Size (O.D.)- The outside diameter of the access tubes.
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Number of - The total number of access tubes in the shaft.
Tubes
Top Elev.- The top elevation of the access tubes.
Bottom Elev.- The bottom elevation of the access tubes.
If the shaft has any secondary reinforcement, or even a second rebar cage, it can be noted by
sketching it in the profile schematic.
CONCRETE TEST DATA SECTION
Class - The class of the concrete used in the shaft from the StandardSpecifications (class A or G typically).
Slump - The measured slump of the concrete.
Air - The measured air content of the concrete.
Date Tested - The date the concrete was tested.
Cylinder - The test cylinder designation number.
Number
Usually the concrete of each drilled shaft is sampled and tested.
OBSERVATIONS SECTION
This section gives the inspector a place to note any irregularities which might have occurred
during the shaft installation. Types of irregularities which should be noted are listed in the
title block of the section. These irregularities should be noted with as much detail as possible,
as it will help the engineers in evaluating the shaft later.
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REFERENCES
1. FHWA-IF-99-025 Drilled Shafts: Construction Procedures and Design Methods, by
Michael W. ONeil and Lymon C. Reese, 1999.
2. Drilled Shaft Inspectors Manual, prepared by the Joint Caisson - Drilled ShaftCommittee of the ADSC: The International Association of Foundation Drilling and DFI:
Deep Foundation Institute, 1989.
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EB 15-025 Page 30 of 30
APPENDIX
Monitoring Forms
The following three pages are the actual monitoring forms. The inspector should make enough
copies for all the drilled shafts on the project. Note that only one of the first two forms (Drilled
Shaft in Rock or Drilled Shaft in Soil) are required for each shaft, depending on the project. The
third form is required for all drilled shafts. Therefore, construction of each drilled shaft should be
documented by two inspection forms.
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EB 15-025 A-1
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EB 15-025 B-1
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