02466Drilled Shafts

DRILLED SHAFTS

PART 1 GENERAL

1.1SECTION INCLUDES

foundations

1.2RELATED SECTIONS

1.3REFERENCES

Concrete Reinforcement

Reinforcement

Ultrasonic Crosshole Testing

Drilled Shafts

1.4DEFINITIONS

been changed by the placement process, such as with excess water or segregation; or concrete containing unintended materials, such as soil or rock from the excavation.

to measure uniformity and integrity of the concrete in deep foundations through use of measured ultrasonic pulses between parallel CSL pipes.

an offset distance between the reinforcing steel and the wall of the drilled shaft hole.

diameter than the supported column and that has a reinforcing steel cage larger than and independent of the column’s reinforcing steel cage.

bottom of drilled shaft hole

to measure uniformity and integrity of the concrete in deep foundations through temperature measurements associated with the heat of hydration generated by concrete as it cures.

position sensors at specific depths along the length of the drilled shaft. The cable is connected to a recording apparatus to collect thermal data for reporting.

1.5SUBMITTALS

which the drilled shaft contractor has installed drilled shafts of a diameter and length similar to those shown, and in similar subsurface conditions

representatives who can verify the drilled shaft contractor’s participation on the listed projects.

Drilled Shafts

shaft superintendent who will be in charge of drilled shaft operations for this project

the listed projects.

are installed according to this Section

concrete pumps, casings, and inspection devices

elevation.

and concrete placement

1) Casing details, size, length, materials, and thickness 2) Description of the method of advancing the casing

report for SID to be used.

centralization methods

concrete placement times

methods.

it workable, for example, admixtures such as retarders or high range water reducers.

where encountered

contain and dispose of water if encountered

required. Include at least the following:

Drilled Shafts

three years in which the integrity testing organization has tested drilled shafts of a diameter and length similar to those shown, and with the same testing method to be used

1) Include the date of recording, shaft number, and camera position in the recording.

the Department’s website for each shaft. 1) Refer to http://www.udot.utah.gov/go/standardsreferences.

placement log for each shaft.

integrity testing is required

results identify substandard concrete integrity, anomalies, or are inconclusive.

date and time of test

versus depth for each pipe pair tested for CSL testing

each thermal wire cable, and the average temperature of all thermal wire cables for TIP testing

inconclusive

by a Professional Engineer (PE) or Professional Structural Engineer (SE) licensed in the State of Utah having at least three years of experience in the interpretation of CSL/TIP results

Drilled Shafts

1.6ACCEPTANCE

concrete compressive strength is less than the specified 28-day minimum compressive strength. Refer to Section 03055.

strength to the measured length of each shaft containing concrete with tested strength less than the specified compressive strength.

required, meeting construction tolerances, and other construction documentation.

as Single-hole Sonic Logging, Gamma-Gamma Nuclear Density Logging, 3D Tomography, and surface Sonic Echo and Impulse Response tests.

competent in the chosen NDT methods.

conditions if the integrity testing and NDT results are inconclusive.

grouting of core holes.

PART 2 PRODUCTS

2.1CONCRETE

2.2REINFORCING STEEL

to Section 03211.

Refer to Section 03211.

Drilled Shafts

to Section 03211. 1) Bars meeting AASHTO M 31, Grade 60 may be substituted if they meet the ductility requirements of ASTM A 706.

foundations.

2.3CASINGS

stresses, and loads from earth and wet concrete.

drilled shaft as shown, but not more than six inches larger.

2.4EQUIPMENT

location, alignment, and to a depth of at least 10 ft beyond the depths shown, in the type of materials present at the shaft locations.

cleanliness of bottom of shaft excavation when required. SID must include at least the following:

the bottom of the drilled shaft hole

steel cage into the drilled shaft.

Drilled Shafts

against a 20 ft head of concrete measured from the discharge end of the pump hose extension of the tremie pipe when placing concrete underwater.

tight couplings straight to within ½ inch in 10 ft.

pump discharge hose but not more than one half the inside diameter of the reinforcing steel cage.

smooth flow of power to the bit, both in rotation and down thrust.

least 15 gallons of water per minute at 200 psi.

of 200 psi, and equipped with a pressure gauge ranging from 0 psi to 1,000 psi.

2.5NON-SHRINK GROUT

CONCRETE REPAIR MORTAR

03924.

PART 3 EXECUTION

3.1GENERAL

Disposal Plan. Follow the authorized Drilled Shaft Integrity Testing Plan when applicable.

compacted.

where top of shaft elevation is above finished ground surface.

Drilled Shafts

3.2DRILLED SHAFT HOLES

determined by Engineer.

during drilling operations.

center, or closer, to an adjacent completed shaft until at least 48 hours after placing concrete for the completed shaft.

diameters center to center from an adjacent completed shaft until at least 24 hours after placing concrete for the completed shaft.

excavation operation is stopped. 1) Install a safety cover. 2) Use a temporary casing to protect the safety of the shaft excavation, surrounding soil, adjacent facilities, and stability of the sidewalls. 3) The Engineer will evaluate design impacts to the shaft due to delays in completion.

holes before placing concrete.

1) Remove loose or disturbed material until at least 50 percent of the bottom of each drilled shaft hole has less than ½ inch of loose or disturbed material. 2) The maximum depth of loose or disturbed material at any location is 1 inch.

throughout its length

drilled shaft hole from caving

present

anticipated

Contractor.

Drilled Shafts

3.3CONSTRUCTION TOLERANCES

3.4REINFORCING STEEL PLACEMENT

before placement of the reinforcing steel.

needed to retain its configuration during handling and installation.

access.

shaft hole.

and alignment during placement.

handling and construction.

drilled shaft, if applicable.

3.5MISCELLANEOUS EMBEDDED ELEMENT PLACEMENT

applicable.

3.6CONCRETE PLACEMENT

A Dry Hole Placement

drilling the shaft hole.

Drilled Shafts

reinforcing steel cage.

concrete.

drilling the shaft hole.

1) Insert a sturdy plastic ball or equivalent into the top of the pump hose extension before connecting the hose from the concrete pump. 2) The ball must fit snugly into the pump hose extension when the hose is filled. The hose must be strong enough to resist rupture. 3) Prime the hose and pipe with cement slurry.

to determine the top surface of concrete.

penetration can be immediately determined.

with soil from the bottom of the hole.

reinforcing steel cage and tremie pipe in the hole.

surface is 10 ft above the bottom of the pipe.

concrete until the placement is complete.

of concrete if the pipe floats.

the top of the concrete surface when withdrawing.

loss of the seal at the end of the tremie pipe occurs:

concrete, and purge it.

Drilled Shafts

placement and continue pumping concrete until all contaminated concrete has lifted to the top of the shaft.

concrete is expelled.

concrete.

surface of the shaft concrete before finishing.

drilled shaft until authorization of integrity test report is received.

make placement of steel reinforcing as shown more difficult.

3.7INTEGRITY TESTING

placement and as recommended by the CSL testing organization. 1) The Engineer may require a longer time if special retarders, mix designs, or other factors result in slower-setting concrete.

substandard concrete integrity or shows inconclusive results.

1½ inch to 2 inch that are compatible with the equipment and methods of the CSL testing organization. 1) Do not use galvanized steel. 2) Provide pipes with a round, regular internal diameter free of defects or obstructions. 3) Provide pipes that are watertight and free from corrosion with clean internal and external faces. 4) Use threaded pipe joints with watertight couplings for pipe extensions.

compounds. Drilled Shafts

5) Fit pipes with a watertight shoe on the bottom and a removable cap on the top.

steel cage: 1) Shafts with diameters up to 48 inch

2) Shafts with diameters greater than 48 inch

rounding up 3) Position pipes parallel to each other and at least 3 inch clear to longitudinal reinforcing

longitudinal reinforcement where the drilled shaft reinforcement prevents this minimum clear spacing

cage. 1) Wire-tie to the reinforcing steel cage at least every 3 ft, or as required for the pipes to stay in position during placement of reinforcing cage and concrete.

least 3 ft above the top of shaft, or if the shaft top is subsurface, at least 3 ft above the ground or water surface. 1) Do not allow the pipes to rest on the bottom of the drilled shaft hole.

after placement of the reinforcing steel (no later than four hours after placement) and cap or seal the pipe tops to keep out debris. 1) Use an ethylene glycol mixture instead of water if shaft construction occurs during winter months and the air temperature near the exposed pipe ends is expected to drop below 30 degrees between the time of concrete placement and the authorization of the integrity test report. 2) Avoid excessive torque, hammering, or other stresses which could break the bond between the tubes and the concrete when removing caps or plugs from the pipes after concrete placement.

integrity test report may identify need for further testing or testing after repair of identified defects.

Drilled Shafts

report has been authorized, required repair of defects has been completed, and the shaft has been repaired to the Engineer’s satisfaction, as follows: 1) Shafts where the supported structure provides at least 3 inch of permanent concrete cover over the top of the shaft across its full diameter

of the drilled shaft. 2) Shafts where the supported structure does not provide at least 3 inch of permanent concrete cover over the top of the shaft across its full diameter

inch below the top of the drilled shaft.

to 3 inches from the top of the pipe. 1) Mix grout to a flowable consistency according to the manufacturer’s instructions.

permanent cover over the cut end of the CSL pipe after the grout sets. 1) Place mortar to the level of the concrete surface +1/8 inch. 2) Follow the manufacturer’s recommendations for finishing and curing.

Embedded Thermal Sensors.

concrete, usually between 12 hours and 4 calendar days after concrete placement, and as recommended by the TIP testing organization.

substandard concrete integrity or shows inconclusive results.

reinforcing steel cage and parallel to the longitudinal reinforcing steel. 1) Shafts with diameters up to 48 inch

Drilled Shafts

2) Shafts with diameters greater than 48 inch

rounding up

an even number of cables to simplify interpretation of results 3) Extend cables to 6 inch from the bottom of shaft. 4) Provide 10 ft of cable length above the top of the shaft. 5) Arrange sensors in a straight line with each sensor spaced at 20 inch or less and at approximately the same elevation as sensors along other thermal sensor wire cables.

of the shaft.

reinforcing steel using nylon zip-ties. 1) Space zip ties at 12 to 20 inch spacing, located midway between sensors along each cable. 2) Do not leave segments of unsecured cable which can be snagged and damaged by movement of the rebar cage or concrete placement.

reinforcing steel cage and before concrete placement.

apparatus shortly after concrete placement. 1) Document which cable is connected to which recording apparatus. 2) Attach the recording apparatus to a secure location well above the top of the concrete.

3.8CORE DRILLING OF DRILLED SHAFT CONCRETE

fully identify the anomaly and determine a course of action when directed by the Engineer.

inner barrel.

excessive wear or loss of diamonds.

Drilled Shafts

there will not be more than 5 ft of laterally unsupported drill rod between the bottom of the drill spindle (chuck) and the top of the shaft concrete when the hydraulic feed is in the up position.

when longer laterally unsupported sections of the drill stem are necessary.

shaft depth at each interval of core recovery.

testing.

as represented by the core samples, is determined to be sound, and notification to continue construction is given by the Engineer.

manufacturer’s instructions.

END OF SECTION

Drilled Shafts