drilled shaft inspector guideline

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DRILLED SHAFT INSPECTORS GUIDELINE

GEOTECHNICAL ENGINEERING MANUAL

GEM-18

Revision #2

AUGUST 2015


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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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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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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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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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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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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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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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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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EB 15-025 Page 29 of 30

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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drilled shaft inspector guideline

Documents