March 2005

Process Industry PracticesStructural

PIP STE02465Augered Cast-in-Place Piles Design Guidelines

PURPOSE AND USE OF PROCESS INDUSTRY PRACTICES

In an effort to minimize the cost of process industry facilities, this Practice hasbeen prepared from the technical requirements in the existing standards of majorindustrial users, contractors, or standards organizations. By harmonizing thesetechnical requirements into a single set of Practices, administrative, application, andengineering costs to both the purchaser and the manufacturer should be reduced. Whilethis Practice is expected to incorporate the majority of requirements of most users,individual applications may involve requirements that will be appended to and takeprecedence over this Practice. Determinations concerning fitness for purpose andparticular matters or application of the Practice to particular project or engineeringsituations should not be made solely on information contained in these materials. Theuse of trade names from time to time should not be viewed as an expression ofpreference but rather recognized as normal usage in the trade. Other brands having thesame specifications are equally correct and may be substituted for those named. AllPractices or guidelines are intended to be consistent with applicable laws andregulations including OSHA requirements. To the extent these Practices or guidelinesshould conflict with OSHA or other applicable laws or regulations, such laws orregulations must be followed. Consult an appropriate professional before applying oracting on any material contained in or suggested by the Practice.

This Practice is subject to revision at any time by the responsible Function Team andwill be reviewed every 5 years. This Practice will be revised, reaffirmed, or withdrawn.Information on whether this Practice has been revised may be found at www.pip.org.

© Process Industry Practices (PIP), Construction Industry Institute, TheUniversity of Texas at Austin, 3925 West Braker Lane (R4500), Austin,Texas 78759. PIP member companies and subscribers may copy this Practicefor their internal use. Changes, overlays, addenda, or modifications of anykind are not permitted within any PIP Practice without the express writtenauthorization of PIP.

PIP will not consider requests for interpretations (inquiries) for this Practice.

Not printed with State funds

March 2005

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Process Industry PracticesStructural

PIP STE02465Augered Cast-in-Place Piles Design Guidelines

Table of Contents

1. Introduction..................................21.1 Purpose ............................................. 21.2 Scope................................................. 2

2. References....................................22.1 Process Industry Practices ................ 22.2 Other References .............................. 2

3. Definitions ....................................2

4. General .........................................3

5. Preaward Meeting ........................3

6. Inspection.....................................4

7. Spoils Handling............................4

8. Grout .............................................4

9. Codes............................................5

10.Pile Integrity Testing ..................5

11.Reinforcement ............................6

12.Obstructions and Payment forPiles .............................................6

13.Basis of Payment ....................... 6

14.Surveying.................................... 7

15.Underground Utility Location.... 7

16.Construction Permits................. 7

17.Test Piles .................................... 7

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1. Introduction

1.1 PurposeThis Practice provides recommendations for the design and installation of augeredcast-in-place piles for use by the engineers and specifiers of augered cast-in-placepiles.

1.2 ScopeThis Practice supplements PIP STS02465 and provides assistance to the engineer inthe preparation of contract documents for furnishing and installing augered cast-in-place piles.

This Practice is modeled on the DFI Augered Cast-in-Place Piles Manual. Foradditional information, refer to that manual and also to the DFI Inspector’s Guide toAugered Cast-in-Place Piles.

This Practice does not describe requirements for lateral displacement or drilleddisplacement piles, also known as augered cast-in-place displacement (ACIP-D)piles. ACIP-D piles may be a good substitute for augered cast-in-place piles in somesoil types/conditions. Because of reduced or eliminated spoils, ACIP-D piles may bea good choice in contaminated soil conditions. However, the different types ofproprietary ACIP-D piles may be more or less suited for different soil conditions.Appropriate engineering, including geotechnical engineering, is required. DFI isdeveloping a practice manual on ACIP-D piles, and the Federal HighwayAdministration is developing a manual on augered cast-in-place piles that addressesACIP-D piles. Both manuals are due out in 2005.

2. References

Applicable parts of the following PIP Practice and other references should be reviewed bythose preparing contract documents for augered cast-in-place piles.

2.1 Process Industry Practices (PIP)– PIP STS02465 - Augered Cast-in-Place Pile Installation Specification

2.2 Other References

• Deep Foundations Institute (DFI)– Augered Cast-in-Place Piles Manual– Inspector’s Guide to Augered Cast-in-Place Piles

• American Society of Civil Engineers (ASCE)– ASCE 7-2002 - Minimum Design Loads for Buildings and Other Structures

3. Definitions

engineer of record: The engineer responsible for structural design of the project

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geotechnical engineer: The party responsible for performing the geotechnical investigationand/or geotechnical consulting during the piling work

inspector: The party responsible for performing inspection during the pile work

owner: The party who owns the facility wherein the augered cast-in-place piles will beinstalled

purchaser: The party who awards the contract to the supplier. The purchaser may be theowner or the owner’s authorized agent.

supplier: The party responsible for furnishing and installing augered cast-in-place piles

4. General

4.1 The recommendations given in this Practice should be considered in design andconstruction of augered cast-in-place pile foundation systems.

4.2 These recommendations are provided because of the unique features of the systemand should be considered because they improve the final product and reduceproblems during construction. These recommendations are not all inclusive, and thespecifications and plans should be reviewed by a geotechnical professionalexperienced in augered cast-in-place pile design and construction.

5. Preaward Meeting

A preaward or preconstruction meeting, including at a minimum the supplier, purchaser,engineer of record, geotechnical engineer, and inspector, should be held to discuss topicssuch as the following.

a. Safety requirements

b. Site entry procedures

c. Available subsurface information

d. Underground utility identification and location

e. Survey for elevation and location of piles

f. Reinforcing steel placement

g. Grout

h. Excavated materials disposal

i. Action required if potentially contaminated soil is encountered

j. Testing and inspection

k. Responsibility for required reports

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6. Inspection

6.1 The inspection data requirements for augered cast-in-place piles during installationdiffer from the data typically obtained for driven piles.

6.2 During pile installation, problems that are difficult to detect can occur, which canreduce the load carrying capacity of the pile. For these reasons, careful, purchaser-retained inspection by an experienced professional (preferably a geotechnicalengineer) on a full-time basis is considered essential.

6.3 Careful attention should be given to the inspection requirements by an experiencedprofessional. Modifications should be made to the inspection requirements to fit thespecific requirements of each project.

6.4 For the inspection, automated instrumentation and monitoring systems to measurevarious elements of the installation process and to produce readout by computer areavailable. If this type of instrumentation is desired and is to be provided by thesupplier, the requirements should be stated by adding an addenda coversheet toinvoke and modify PIP STS02465, Section 4.2.3. The instrumentation will be anadditional cost to the purchaser. Even if the instrumentation is provided by thesupplier, a qualified inspector should be present during the pile work. The specialinstrumentation is not normally used or available for piles installed in areas havingrestricted headroom conditions.

7. Spoils Handling

7.1 The drilling process produces spoils in the form of excess grout and soil returned tothe surface by the augers.

7.2 The contract documents should clearly state which party is responsible for removingand disposing spoils, any restrictions on the disposal, and location of a disposal areathat the owner can provide, if any.

7.3 If the soil is contaminated, handling and disposal costs should be considered indetermining the feasibility of the system.

7.4 If contaminated spoil disposal is an issue, but drilled piles are preferred over drivenpiles, augered cast-in-place displacement (ACIP-D) piles may be considered (seeSection 2, this Practice). All types of ACIP-D piles do not necessarily eliminatespoils, but they at least significantly reduce the quantity of spoils.

8. Grout

8.1 The required grout strength should be designated on the plans if other than the4,000 psi (27,580 kPa) at 28 days “default” given in PIP STS02465,Section 4.3.2.7.3.

8.2 Allowable maximum grout temperature and holding time stated in PIP STS02465,Section 4.3.2.7.5, differ from the temperatures and holding times given in the DFIAugered Cast-in-Place Piles Manual guideline specification. However, as also notedin the DFI Augered Cast-in-Place Piles Manual commentary, opinions differ aboutthe allowable maximum temperature, and some think that 90°F (32°C) should be the

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maximum (same as given in PIP STS02465). The DFI Augered Cast-in-Place PilesManual also notes that excessive mixing time and temperature can be detrimental togrout strength.

8.3 As stated in Section 8.2 (this Practice), the requirements in PIP STS02465 are basedon 90°F (32°C) allowable maximum temperature. As a result, if a higher andpotentially detrimental grout temperature is considered on a particular project or isrequested by the supplier, the engineer of record is alerted and given the opportunityto consider whether to allow higher temperatures. If greater temperatures and/orextended holding times are allowed, special procedures for grouting should bedeveloped and followed. It is recommended that additional strength test cubes thatrepresent grout placed at high temperatures and/or after extended holding times bemade. To prepare for an occurrence of low strength test results, definitions ofremedial actions and assignment of responsibility for the actions should be made andagreed upon beforehand.

8.4 The minimum theoretical grout volume specified in PIP STS02465, Section 4.4.6.13,should be increased as necessary to match the volume used in the test piles and/orthe recommendations of the geotechnical engineer, which are made according to soiltype encountered during soil borings.

9. Codes

9.1 Governing codes should be checked for limitations that are more restrictive thanthose in PIP STS02465. Some building codes place specific limits on design stresses(and/or maximum loads) for this type of pile.

9.2 Codes should be checked for other limitations, such as spacing between pilesconstructed within 24 hours of one another, reinforcing cover, length to diameterratio, etc.

10. Pile Integrity Testing

10.1 Low-strain integrity testing is a relatively quick and inexpensive method ofnondestructive assessment of pile cross-sectional integrity, though subject tolimitations. If questions arise about the acceptability of piles, such testing may be auseful tool for the engineer to help assess possible problems.

10.2 In some cases, it may be appropriate to perform low-strain integrity testing on a pre-determined portion of the completed piles. The engineer should determine thenumber of piles to be tested. Low-strain integrity testing should be limited to pileswith length-to-diameter ratios of less than 30. The use of low-strain integrity testingcan cause coordination problems and increase job costs even if the piles aredetermined to be acceptable. This is especially true if the tests are not completed atthe same time that the pile installation is completed.

10.3 Cross-hole sonic logging has been used to evaluate integrity of larger (diametersgreater than 24 inches (600 mm) piles. Single-hole sonic logging can be used forpiles with diameters of 24 inches (600 mm) or less. The viability of this system mustbe carefully assessed for usefulness on a particular project.

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10.4 Specifications should cover acceptance requirements if integrity problems areindicated by these methods.

10.5 Pile integrity testing does not reduce the need for qualified, full-time pile installationinspection. A qualified inspector should be present during the pile work regardless ofwhether pile integrity testing is performed.

11. Reinforcement

11.1 Reinforcement cages, if required, should be limited in length to the minimumactually needed for moment and shear resistance.

11.2 Cages longer than about 20 to 25 ft (6 to 8 m) are difficult or impossible to install. Ifpossible, cages should be limited to approximately 15-ft (4.5-m) length. Installationof cages longer than 25 ft (8 m) is normally unsuccessful.

11.3 Full-length single bar reinforcement is commonly employed for tension piles.

11.4 Longitudinal reinforcement and spiral confining steel (or suitable alternativereinforcement) may be needed to withstand seismic pile-soil interaction loadingconditions, particularly if these piles derive a significant share of their support in endbearing resistance during and immediately after a major earthquake. Competentgeotechnical and structural engineers should confirm the suitability of thesefoundation elements for the expected loading/distortion conditions.

11.5 According to ASCE 7-2002, Section A9.7.5.4.1, full-length reinforcement cages arerequired in piles for structures in Seismic Design Category E or F. Accommodationsin the design should be made by the engineer of record to facilitate the installation offull-length cages, such as bending reinforcement bars toward the center at the bottomof the cage so that the cage does not catch on the sides of the pile grout hole. In suchcases, the supplier should provide a plan to assure that a full-length cage can beinstalled. In certain soil conditions with deep piles, this requirement may precludethe use of augered cast-in-place piles. A sufficient quantity of grout to complete apile should be at the site before pile installation begins.

12. Obstructions and Payment for Piles

12.1 Requirements should be stated for handling piling installation obstructions ifencountered.

12.2 Even with a rock bit, augered cast-in-place pile rigs cannot penetrate a significantdistance into hard rock, and rock bits may not penetrate many obstructions.

12.3 A payment calculation method for short piles terminated because of obstructionsshould be stated in the contract documents. Commonly, a pile that cannot becompleted to full length because of an obstruction is completed otherwise inaccordance with the pile termination requirements, and the supplier is paid for thelength installed.

13. Basis of Payment

13.1 The basis for payment should be stated in the contract documents.

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13.2 Typically, the best pricing for the purchaser can be obtained by requesting lump sumbids for the entire installation of the piles and requesting unit pricing for over andunder the bid quantity of piles.

14. Surveying

14.1 The contract documents should clearly state which party is responsible for the surveylocating the piles and marking cut-off elevations.

14.2 Location of benchmarks and description of datum plane should be provided, ifappropriate.

15. Underground Utility Location

The responsibility for identifying, locating, and marking underground utilities should beclearly defined.

16. Construction Permits

16.1 Responsibility for permits should be made clear in the contract documents.

16.2 Permits required from regulatory agencies should normally be stated to be theresponsibility of the supplier.

16.3 Permits that the supplier shall obtain from the owner/purchaser should be clearly andcompletely described.

17. Test Piles

17.1 The contract drawings should show the location, length, number, etc., of probeand/or test piles. See PIP STS02465, Section 4.4.5.1.

17.2 The type of load tests (compression, tension, and lateral) should be designated on thecontract drawings. See PIP STS02465, Section 4.4.5.2.

17.3 Details of telltales or strain gauges for test piles should be provided. SeePIP STS02465, Section 4.4.5.5.

17.4 The type of test loading procedure should be designated for compression load tests ifdifferent from PIP STS02465, Section 4.4.5.12.

17.5 If tension or lateral testing is required, the type of test loading procedure should bedesignated.

17.6 If dynamic load testing is required, a written procedure for dynamic load testingshould be provided.

17.7 If dynamic load testing is required, written assurance should be provided from aprofessional engineer that the dynamic load testing procedure will yield results thatdefine the allowable load capacities of the piles.

17.8 The viability of dynamic load testing, its applicability to a specific project, theassurance that the testing will not harm the structural integrity of the pile, and the

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justified degree of confidence to be assigned to the results should be considered inchoosing to allow this type of testing and accounted for in selecting the pile designcapacities. Further, the applicable building code must be checked to determinewhether dynamic testing is allowed.