COMPLETE REVISION February Process Industry Practices Structural. PIP STE02465 Augered Cast-in-Place Piles Design Guide

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1 February 2012 Process Industry Practices Structural PIP STE02465 Augered Cast-in-Place Piles Design Guide

2 PURPOSE AND USE OF PROCESS INDUSTRY PRACTICES In an effort to minimize the cost of process industry facilities, this Practice has been prepared from the technical requirements in the existing standards of major industrial users, contractors, or standards organizations. By harmonizing these technical requirements into a single set of Practices, administrative, application, and engineering costs to both the purchaser and the manufacturer should be reduced. While this Practice is expected to incorporate the majority of requirements of most users, individual applications may involve requirements that will be appended to and take precedence over this Practice. Determinations concerning fitness for purpose and particular matters or application of the Practice to particular project or engineering situations should not be made solely on information contained in these materials. The use of trade names from time to time should not be viewed as an expression of preference but rather recognized as normal usage in the trade. Other brands having the same specifications are equally correct and may be substituted for those named. All Practices or guidelines are intended to be consistent with applicable laws and regulations including OSHA requirements. To the extent these Practices or guidelines should conflict with OSHA or other applicable laws or regulations, such laws or regulations must be followed. Consult an appropriate professional before applying or acting on any material contained in or suggested by the Practice. This Practice is subject to revision at any time. Process Industry Practices (PIP), Construction Industry Institute, The University of Texas at Austin, 3925 West Braker Lane (R4500), Austin, Texas PIP Member Companies and Subscribers may copy this Practice for their internal use. Changes or modifications of any kind are not permitted within any PIP Practice without the express written authorization of PIP. Authorized Users may attach addenda or overlays to clearly indicate modifications or exceptions to specific sections of PIP Practices. Authorized Users may provide their clients, suppliers and contractors with copies of the Practice solely for Authorized Users purposes. These purposes include but are not limited to the procurement process (e.g., as attachments to requests for quotation/ purchase orders or requests for proposals/contracts) and preparation and issue of design engineering deliverables for use on a specific project by Authorized User s client. PIP s copyright notices must be clearly indicated and unequivocally incorporated in documents where an Authorized User desires to provide any third party with copies of the Practice. PRINTING HISTORY March 2005 Issued February 2012 Complete Revision Not printed with State funds

3 February 2012 Process Industry Practices Structural PIP STE02465 Augered Cast-in-Place Piles Design Guide Table of Contents 1. Introduction Purpose Scope References Process Industry Practices Industry Codes and Standards Government Regulations and Documents Definitions General General Guidelines Meetings Design of ACIP Piles Submittals Materials Equipment Execution Quality Assurance Inspection ACIP Pile Integrity Verification ACIP Pile Capacity Verification Payment Guidelines Basis of Payment Obstructions and Payment for Obstructed Piles Process Industry Practices Page 1 of 30

4 1. Introduction 1.1 Purpose This Practice provides guidelines for the design and installation of augered cast-in-place (ACIP) piles. 1.2 Scope 2. References This Practice complements PIP STS02465 and provides assistance to the engineer in the preparation of contract documents for furnishing and installing ACIP piles. This Practice is modeled on DFI TM-ACIP-1 (Augered Cast-in-Place Piles Manual). For additional information, refer to that manual and also to DFI TM-ACIP-2 (Augered Castin-Place Piles Inspector s Guide). This Practice does not provide guidelines for lateral displacement or drilled displacement piles, also known as augered cast-in-place displacement (ACIP-D) piles. DFI manuals, the Federal Highway Administration documents and a geotechnical engineer with experience designing ACIP-D piles should be consulted for guidance on ACIP-D piles. Applicable parts of the following Practices, industry codes and standards, and other references shall be considered an integral part of this Practice. The edition in effect on the date of contract award shall be used, except as otherwise noted. Short titles will be used herein where appropriate. 2.1 Process Industry Practices (PIP) PIP STS Augered Cast-in-Place Piles Installation Specification 2.2 Industry Codes and Standards American Concrete Institute (ACI) ACI 212.3R - Report on Chemical Admixtures for Concrete ACI Specifications for Structural Concrete ACI 301M - Specifications for Structural Concrete (Metric) American Society of Civil Engineers (ASCE) ASCE/SEI 7 - Minimum Design Loads for Buildings and Other Structures ASTM International (ASTM) ASTM C494/C494M - Standard Specification for Chemical Admixtures for Concrete ASTM D1143/D1143M - Standard Test Methods for Deep Foundations Under Static Axial Compressive Load ASTM D Standard Test Method for Low Strain Impact Integrity Testing of Deep Foundations ASTM D Standard Test Method for Integrity Testing of Concrete Deep Foundations by Ultrasonic Crosshole Testing Deep Foundations Institute (DFI) TM-ACIP-1 - Augered Cast-in-Place Piles Manual (Second Ed. 2003) Process Industry Practices Page 2 of 30

5 TM-ACIP-2 - Augered Cast-in-Place Piles Inspector s Guide (Second Ed. 2010) 2.3 Government Regulations and Documents 3. Definitions Federal Highway Administration Geotechnical Engineering Circular No. 8 Design and Construction of Continuous Flight Auger (CFA) Piles April 2007 Occupational Safety and Health Administration (OSHA) 29CFR Part 1926 Safety and Health Regulations for Construction constructor: The party responsible for supplying the materials, equipment, tools, supervision, and labor for the installation of the ACIP piles in accordance with the contract documents. The term constructor shall apply also to the constructor s subcontractor(s) and vendor(s). contract documents: Any and all documents, including codes, studies, design drawings, specifications, sketches, practices, and data sheets, that the purchaser or engineer of record has transmitted or otherwise communicated, either by incorporation or reference, and made part of the legal contract agreement or purchase order between the purchaser and the constructor engineer of record: Purchaser s authorized representative with overall authority and responsibility for the engineering design, quality, and performance of the civil works, structure, foundations, materials, and appurtenances described in the contract documents. The engineer of record shall be licensed as defined by the laws of the locality in which the work is to be constructed, and be qualified to practice in the specialty discipline required for the work described in the contract documents. geotechnical engineer: The professional engineer responsible for performing the geotechnical investigation and/or geotechnical consulting during foundation design, construction of civil works, installation of foundations, or other services as required by the owner, purchaser or engineer of record inspector: Third party inspector retained by the constructor, responsible for observation and recording of material verification, pile installation, and other quality control documentation. (This is not the qualified geotechnical representative.) owner: The party who has authority through ownership, lease, or other legal agreement over the site, facility, structure or project wherein the ACIP piles will be installed professional engineer: An engineer, other than the engineer of record licensed as defined by the laws of the locality in which the project is to be constructed and qualified to practice in the specialty discipline required for the work described in the contract documents purchaser: The party who awards the contract to the constructor. The purchaser may be the owner or the owner s authorized agent. qualified geotechnical representative: The qualified geotechnical representative shall be a graduate geotechnical engineer, graduate geologist, or geotechnical technician provided the technician has at least ten years of relevant field exploration and logging experience. The qualified geotechnical representative shall work under the supervision of the geotechnical engineer. Process Industry Practices Page 3 of 30

6 4. General 4.1 General Guidelines Guidelines in this Practice should be considered in design and construction of ACIP pile foundation systems These guidelines address the unique features of the system and should improve the final product and reduce problems during construction. These guidelines are not all inclusive, and the specifications and plans should be reviewed by a geotechnical engineer experienced in ACIP pile design and construction ACIP piles typically have diameters from 12 to 36 in (300 to 900 mm) and lengths commonly up to 100 ft (30 m) with longer piles in some cases. The trend in the US is towards the larger 24- to 36-in (600- to 900-mm) diameters. European practice has included up to 60 in (1500 mm) diameter piles. US practice will likely follow Advantages of ACIP Piles 1. Construction cost is generally lower than driven piles and drilled piers, partly due to local crane rental, smaller installation equipment and locally available materials (grout and rebar) 2. Noise and vibration disturbances are much lower than driven piles 3. Auger protects hole from caving, reducing potential for ground movement 4. Pressure injected grout provides good bond and provides some compaction of the soil 5. Useable in a wide variety of soils 6. Automated monitoring can provide continuous record of grout installed Disadvantages of ACIP Piles 1. Lower load capacity than driven piles or drilled piers 2. Quality and integrity highly dependent on skills of the operators 3. Augering in loose sands can lower the soil lateral stresses 4. Equipment breakdowns can cause pile abandonment 5. Reinforcing steel placement can be difficult if dense reinforcement is required 6. Typically ACIP piles cannot be used in soils with cobbles or boulders due to excavation difficulty 7. Typically ACIP piles cannot be used in soft, highly organic soils because the soil compresses excessively using large volumes of grout 8. There is no check on capacity during construction such as the blow count during driving of driven piles. Auger torque is apparently not useful as an indicator Contracting / Responsibility Contract documents should specify the party responsible for all tasks. Split contracting is not advisable. Generally, the constructor should be Process Industry Practices Page 4 of 30

7 responsible for all phases of constructing the ACIP piles including safety, construction permits, sourcing of materials, suitable equipment, experienced manpower, installation schedule, third-party testing, load testing, and other items required for the successful installation. Specifically, the constructor of the ACIP piles should be responsible for safety, drilling, grout procurement, grout placement, reinforcing assembly procurement whether site-built or shop-fabricated, installation of reinforcing assembly, monitoring ACIP piles for grout settlement, maintaining grout level in ACIP piles with grout, protection of ACIP piles against contamination, during curing, and pile load testing The engineer of record and design engineer should review the subsurface investigation and the structural load report before designing the piles and foundation necessary to carry the loads Data from subsurface investigation(s) must be reviewed by the constructor. Such data should not be construed to represent subsurface conditions at locations other than the specific boring/sounding location indicated. Constructor should understand the soil conditions at the site and provide suitable equipment to function under the conditions at the site. Additional investigations may be performed at the constructor s own discretion and expense with the approval of the engineer of record provided the results are reviewed by the owner s geotechnical engineer Surveying Contract documents should specify the party responsible for the survey laying out the piles and marking cut-off elevations Location of benchmarks and description of datum plane should be provided, if appropriate Contract documents should specify the party responsible for the survey locating the as-built pile locations and elevations Underground Utility Location Contract documents should specify the party responsible for identifying, locating, and marking underground utilities Construction Permits Contract documents should specify the party responsible for providing construction permits Obtaining construction permits from regulatory agencies should typically be the responsibility of the constructor Construction permits that the owner/purchaser furnishes to the constructor should be clearly and completely described in the contract documents. Process Industry Practices Page 5 of 30

8 4.2 Meetings Pre-award Meeting A pre-award meeting, attended by the constructor, purchaser, engineer of record, geotechnical engineer, qualified geotechnical representative, and inspector, should be held to discuss topics such as the following: a. Safety requirements including safety inspection of cranes to be used for pile installation b. Site entry procedures c. Available subsurface information d. Underground utility identification and location e. Survey for elevation and location of piles f. Grout submittal, delivery and placement requirements g. Excavated materials disposal h. Action required if potentially contaminated soil is encountered i. Planning for integrity testing, load testing, and inspection j. Test pile installation and procedures. Qualification and experience of the operator(s) to be assigned on the job for installation of production piles. k. Project pile specification review l. Grout pump calibration and computation of minimum required pump strokes m. Procedures for drilling the piles n. Procedures for grout placement o. Procedures for re-drilling and re-grouting piles p. Procedures for finishing pile tops to final grade (topping off or bailing grout below ground surface) q. Chain of communication for piles not meeting specification requirements r. Responsibility for required reports Pre-Construction Meeting A pre-construction meeting should be held immediately before start of work. This meeting should be attended by the people assigned to the work and who are ultimately responsible for the actual field pile installation work. These people include the constructor, inspector, field superintendent, foremen, operators, installation crew, and grout supplier. The topics addressed should be similar to those listed in Section but should go into greater detail on actual installation procedures (e.g., grout pump installation, rebar spacers, rebar cage handling, and other functional topics). The project specifications should be reviewed with the construction personnel to ensure full understanding of the requirements. The constructor, purchaser, engineer of record, qualified geotechnical Process Industry Practices Page 6 of 30

9 representative, and geotechnical engineer, should also attend to discuss or explain topics Pre-construction meeting topics list: Comment: 4.3 Design of ACIP Piles 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. Grout submittal and placement requirements. g. Excavated materials disposal h. Action required if potentially contaminated soil is encountered i. Testing and inspection j. Test pile installation and procedures k. Review project pile specification l. Grout pump calibration and computation of minimum required pump strokes m. Procedures for drilling the piles including pile spacing requirements. n. Procedures for grout placement o. Procedures for re-drilling and re-grouting piles p. Procedures for installation of reinforcing cages, center reinforcing bars, centralizers, and NDT access tubes. q. Procedures for finishing pile tops to final grade (topping off or bailing grout below ground surface, setting top forms, also known as cut-off ) r. Chain of communication for piles not meeting specification requirements s. Responsibility for required reports See the DFI TM-ACIP-2 for more information and commentary on the pre-construction meeting The engineer of record and design engineer are directed to the Federal Highway Administration Geotechnical Engineering Circular No. 8 for a comprehensive review of design methods for ACIP piles Normally a minimum of 115% of the theoretical grout volume is placed in each 5-ft (1.5-m) increment of pile. The geotechnical engineer normally determines the minimum grout volume for the soil stratigraphy. In some very stiff soils or soft rock, the unit volume could be reduced to 100% through the very stiff soils. Process Industry Practices Page 7 of 30

10 In soft soils or soils with voids the unit grout volume can be significantly larger than the theoretical volume. In some instances, the grout head will exceed the shear capacity of the soil resulting in very large grout unit volumes. In such an instance, ACIP piles may not be suitable Design loads for ACIP piles shall be determined in accordance with minimum load requirements described in ASCE/SEI Governing building codes should be checked for limitations that are more restrictive than those in PIP STS Some building codes place specific limits on design stresses and/or maximum loads for ACIP piles. Local codes may also restrict spacing between piles constructed within 24 hours of one another, reinforcing cover, length to diameter ratio, etc. 4.4 Submittals Preconstruction Submittals The following items should be submitted to the engineer of record for review at least 14 calendar days before mobilization begins: a. Description of the pile drilling and pumping equipment to be used on the project, including the hollow stem auger, drill bit, leads/torque arm, drive box (horsepower, weight, and torque), hydraulic power unit, torque converter, grout pump, and safety inspection report of crane(s) to be utilized at site for pile installation b. Description of anticipated production in linear feet (meters) of completed piling per rig, per day c. Proposed grout mix, admixtures, and descriptions of grout components. Grout mix proportioning and compliance verification should be in accordance with ACI 301/ACI 301M. d. Drawings indicating the arrangement of the pile static load test and all design calculations, when applicable. A professional engineer shall seal the drawings and calculations. Calibrations of load-cell and jack/jack manometer shall also be included. Calibrations shall be current for this project only and shall be performed immediately before equipment is brought to the site. e. Descriptions and calibrations of the dynamic loading equipment and qualifications of the testing technicians, when applicable f. Permits as required by the contract documents g. Piling plan layout referenced to the drawings, including a numbering system capable of identifying each individual pile h. Certified mill test reports for reinforcing steel, when applicable i. A complete pile installation procedure in accordance with the project specifications, this practice, and the DFI manuals referenced above. Installation procedures and equipment should be the same as those used to install the test piles. Constructor should notify the engineer of record immediately if the pile installation procedure and/or equipment are changed for any reason. Process Industry Practices Page 8 of 30

11 j. Details of methods to be used for centering reinforcing in the piles k. Written statement that mobilized equipment will be capable of accessing the location and installing the ACIP piles at the required location and depth in accordance with the contract documents l. Checked reinforcement bar fabrication drawings showing details of splice length for vertical bars and tie details m. Drawing and written description of teeth design and material, and picture of the rock-cutting bit to be used if applicable n. Descriptions of automated installation-monitoring equipment o. Descriptions of low-strain pulse echo (LSPE) integrity testing equipment and procedures and qualifications of testing technician if specified as a responsibility of the constructor Construction Submittals Inspector shall prepare a pile installation record using the attached data form PIP STS02465-D or PIP STS02465-DM (as applicable) for each pile and provide to the qualified geotechnical representative for immediate review. Inspector shall distribute one copy each to: the constructor, the purchaser, the engineer of record, and the geotechnical engineer within 2 working days of installation. The inspector shall record the following information at a minimum: a. Pile number b. Project name, number, and location c. Name of constructor d. Date of installation, weather conditions, and temperature e. Pile inspector s name and signature f. Rig: identification number, model number and operator s name g. Grout supplier, grout truck number, grout ticket number, time grout was batched, grout truck arrival time on-site, batch volume (load) h. Amount and type of admixture(s) added to each grout truck on-site i. Amount of water added to each grout truck on-site j. Grout mix number, grout sampling time, grout temperature k. Flow cone time in seconds [Cone orifice diameter is 3/4 inch (20 mm) as required by specification] l. Grout cube /cylinder sets made by the inspector with time and identification m. Drawing numbers of pile detail and pile location n. Design pile diameter o. Auger diameter (note actual diameter each time measured in field) Process Industry Practices Page 9 of 30

12 p. Auger pitch (note actual pitch each time measured in field; average the measured length between a minimum of six auger flights) q. Ground surface elevation r. Pile top elevation (cut-off) s. Design tip of pile elevation, t. As-built length of pile u. Alignment of crane leads (vertical or battered with angle) v. Augering start time (pile excavation began) w. Number of auger revolutions per 5-ft (1.5-m) increment of pile penetration while drilling down x. Augering stop time (pile tip elevation reached) y. Total time of excavation (note in blank space) z. Depth of pile aa. Pile tip elevation (subtract depth from ground surface elevation) bb. Theoretical volume (calculate from auger diameter and depth of pile) cc. Time grout pumping began dd. Grout pump strokes for each 5-ft (1.5-m) increment of pile grout [2-ft (0.6-m) increment if automated monitoring equipment is used] ee. Grout factor per increment (calculate actual/theoretical volume) (Convert pump strokes into quantity of grout placed for each 5-ft (1.5-m) increment of pile versus theoretical quantity of grout [2-ft (0.6-m) increment if automated monitoring equipment is used] ff. Time grout pumping ceased gg. Total time of grout placement (note in blank space) hh. Pump strokes for grout placed to build initial pressure head ii. jj. Total pump strokes to complete pile Grout return (grout head when the grout is first observed at the ground surface) kk. Overall grout factor (actual grout volume pumped into the pile divided by theoretical grout volume; the grout factor shall not include the grout required to fill the lines or auger, nor any excess grout pumped at the ground surface.) ll. Reinforcing steel placed (time, meets drawing requirements, centralizers, etc.) mm. Elevation of top of steel nn. Pile top form placed and finished (time) oo. Any unusual occurrences during the pile installation Process Industry Practices Page 10 of 30

13 pp. Theoretical volume of excavation (theoretical diameter = diameter of auger) qq. Total number of pump strokes to complete pile (actual grout volume) rr. ss. Grout settlement, description of communication with adjacent piles (if any) Printed copy of automated measuring and recording equipment output Grout compression test results should be submitted to the purchaser within five days of performing test. Engineer of record should be notified immediately if any test indicates that the grout is below the specified strength Constructor should provide an electronic QA/QC spreadsheet that links the pile installation records with cube strength values and other test results. The spreadsheet should be updated daily during ACIP pile installation and on receipt of cube strength or other test results Constructor should provide to the purchaser a printed copy of the automated measuring and recording equipment output as described in Section 4.4.3, and should provide a copy with the pile installation record described in Section Inspector should notify the constructor immediately of any concerns regarding the pile installation, and should document the concern on the pile installation record Inspector s qualifications should be reviewed and approved by the geotechnical engineer Inspection records should be reviewed by the geotechnical engineer within three business days of pile installation. Deficiencies identified in the pile installation record should be resolved; such resolution may include testing as specified by the geotechnical engineer Automated Instrumentation and Monitoring Submittal Constructor should provide to the purchaser information describing the automated instrumentation and monitoring equipment to be used for all piles on the job As a minimum the submittal should contain the following information: a. Manufacturer and model of the equipment and components. b. Description of the equipments function c. Sample of the information and printout provided d. Certification that the equipment can measure the parameters desired by the engineer of record and by the constructor e. Operating manual of the equipment Process Industry Practices Page 11 of 30

14 4.5 Materials Component materials should be as specified in PIP STS Grout Mixes Required grout strength should be specified on the plans if other than the 4,000 psi (28 MPa) at 28 days default specified in PIP STS02465, Section Allowable maximum grout temperature and holding time stated in PIP STS02465, Section , are the same as the temperatures and holding times given in DFI TM-ACIP-1. However, as noted in the DFI TM-ACIP-1 commentary, opinions differ about the allowable maximum grout temperature, and some think that 90 F (32 C) should be the maximum. The DFI TM-ACIP-1 warns that excessive mixing time and temperature can be detrimental to grout strength. Comment: Typically a grout with cementitious materials of 750 lb (340 kg) of Portland cement and 225 lb (102-kg) of fly ash and proper combination of admixtures can have a slow heat gain that permits placement at a greater temperature. Testing is necessary to ensure the desired properties are maintained. Grout suppliers sometimes change admixtures and mix design without notice. Note that in hot weather, the grout is placed in a drilled hole whose temperature can be significantly less than ambient Requirements in PIP STS02465 are based on 100 F (38 C) allowable maximum temperature and 70 F (21 C) minimum delivery temperature. If a higher or lower grout temperature that could be potentially detrimental is requested by the constructor and/or grout supplier, the engineer of record and geotechnical engineer should be alerted and given the opportunity to consider whether to permit higher temperatures. Typical delivery time should be 30 to 45 minutes depending on weather and other conditions. At 100 F (38 C) the maximum delivery time is two hours; maximum placement temperature will depend on mix design, weather, and other factors Greater or lower grout temperatures and/or extended holding times are permitted provided special procedures for grouting are developed and followed. Additional strength test cubes that represent grout placed at higher or lower temperatures and/or after extended holding times should be made. To prepare for an occurrence of low strength test results, definitions of remedial actions and assignment of responsibility for the actions should be made and agreed upon beforehand. Comment: Cubes are used for sand grout with a maximum size aggregate of #16 sieve (1.18 mm). Small cylinders [3 in x 6 in (75 mm x 150 mm)] may be used for pea gravel concrete. Full size cylinders [6 inches x 12 in (150 mm x 300 mm)] should be used for concrete with 3/4 in (20 mm) aggregate. If used, ensure that equipment is sized to utilize grouts or concretes specified. Process Industry Practices Page 12 of 30

15 Minimum theoretical grout volume (115%) as specified in PIP STS02465, Section , should be increased as necessary in accordance with the volume used in the test piles and/or the recommendations of the geotechnical engineer, based on the soil type encountered during soil borings Chemical admixtures are often used to improve the performance of the grout. See ACI 212.3R for use of admixtures. Admixtures should meet the requirements of ASTM C494/C494M. Use of air entraining admixture as a substitute for fluidifier or other admixtures should be prohibited due to the potential for causing poor grout strength Initial mixing time after final addition of all ingredients is typically one minute for the first cubic yard (0.75 m 3 ) and additional 15 seconds for each cubic yard (0.75 m 3 ) thereafter Grout mix should be assigned a mix number that will be included on the grout delivery tickets for identification purposes so the independent testing agency s inspector can verify that the correct mix was delivered and placed in the production piles Sufficient quantity of grout to complete a pile should be at the site before pile installation begins. Comment: This is for each pile in turn not the whole day or job. The grout trucks are to be readily available at the job site Grout test cubes should be prepared during mix design development, during daily installation operations, and for each load tested pile During daily installation operations of 8 to 10 hours, two sets of grout cubes from different grout trucks for each pile installation rig. If extended hour daily operations are used, no more than four sets of cubes per rig should be prepared in a 24-hour day unless directed by the inspector Grout cubes prepared for test piles should be tested as follows: two cubes at 7 days, two cubes at 14 days, two cubes at 28 days, two cubes on the same day the pile load test is conducted and four cubes held in reserve A simple cup test can be used by the inspector in the field to determine approximate time of initial set. The inspector simply fills a number of Styrofoam drink cups with grout and places them in a shaded and cool place. At intervals, the inspector will turn a single cup over and note the time and behavior of the grout. At the time the grout comes out as a cupshaped block and only slightly plastic, that is the time of initial set. Initial set is the minimum time between which adjacent piles can be placed. Note that PIP STS02465, Section requires that 12 hours elapse before adjacent piles can be placed Workability/consistency is measured using a flow cone which should be in accordance with ASTM C939, except that the cone shall be modified to provide a 3/4-in (20-mm) opening. Grout flow rates should be between 10 and 25 seconds. Process Industry Practices Page 13 of 30

16 4.5.2 Reinforcement General Reinforcing Practice 1. Reinforcement cage bars should be limited to the minimum length required for moment, shear and/or tension resistance. 2. P-y analysis should be provided by the geotechnical engineer for piles subject to moment, shear and tension. (Soil resistance p vs. pile deflection y) 3. Typically, ACIP pile reinforcing steel cages are designed using bars of the same length. If cages can be kept to 15 to 25 ft (4.5 to 8 m), it is unlikely that there are benefits in stopping bars at different locations. Shortening the reinforcing steel cage to this length can help reduce construction problems and increase pile installation rates. 4. Cage design should consider the need for grout to freely flow between the bars. Multi-layer cages are very difficult to install. Consider using larger diameter piles with single-layer cages composed of larger diameter bars. 5. Stiffen the reinforcing cages for handling by tying all bar intersections tightly with wire. Tie material must be compatible with the reinforcing. Reinforcing cages or bars must be clean and free of deleterious material before insertion into the grout to assure good adhesion. In hot weather, the cages or bars should be sprayed with water just before insertion to cool the reinforcing. This improves the bar to grout bond. 6. Tops of the piles should be carefully screened to fresh concrete before reinforcing is placed. 7. Reinforcing steel should not be forced into the grout filled pile shaft using a backhoe or other mechanical equipment. 8. Pile Installation Records should be annotated if the reinforcing steel was placed into the pile smoothly without encountering any obstructions Long Reinforcing Cages 1. Reinforcing cages longer than 20 to 25 ft (6 to 8 m) can be difficult or impossible to properly install, as are multi-layered cages. If longer cages are required, the structural engineer and geotechnical engineer should review the soil profile and revise the minimum grout quantity and diameter to ensure proper placement. 2. Sufficient spacing should be provided between reinforcing bars to permit free flow of grout. If the reinforcing spacing is less than five times the maximum diameter of the aggregate, a larger diameter pile should be specified, or the reinforcing bar size should be adjusted to improve the flow of grout. Process Industry Practices Page 14 of 30

17 3. Separate crane to handle and install long reinforcing cages should be considered. A crane can improve the cage installation, reduce damage to the cage, reduce contamination of the cage due to mud, and release the drilling rig to continue work. Typically, few problems are experienced if the cages are placed within 10 to 15 minutes of pile top screening. 4. Tension piles typically use a single full-length reinforcement bar. 5. Longitudinal reinforcement and spiral confining steel (or suitable alternative reinforcement) can be used to withstand seismic pilesoil interaction loading conditions, particularly if these piles derive a significant share of their support in end bearing resistance during and immediately after a major earthquake. Geotechnical and structural engineers, competent in seismic design, should confirm the suitability of these foundation elements for the expected loading/distortion conditions Full-Length Reinforcement Cages 1. Refer to ASCE/SEI 7 for requirements for full-length reinforcement cages in piles for structures in high Seismic Design Categories. 2. Cage design should facilitate the installation of full-length cages (e.g., bending reinforcement bars toward the center at the bottom of the cage to reduce the likelihood that it will catch on the sides of the pile grout hole). 3. Constructor should provide a plan to assure that a full-length cage can be installed. 4. Full-length reinforcing cages can preclude the use of ACIP piles as deep piles in some soil conditions Reinforcement Hooks 1. Requirements for hooks on the reinforcing cages should be carefully evaluated as hooks can cause difficulty in placement. 2. Often the top of the pile is below ground and the hooks are field bent. Field bending of reinforcing bars is essentially limited to # 7 bars (#22 metric bars) or less. Larger bars bend more slowly and require special procedures. 3. Bar bends should be limited to 90-degree bends. 4. Pre-assembled cages with hooked bars can be difficult to assemble, place efficiently on delivery trucks, and handle in the field. To maintain the desired # 7 bar (#22 metric bars) size, the number of bars may be increased. If increasing the number of bars reduces the spacing below the minimum, the diameter of the pile may be increased. Process Industry Practices Page 15 of 30

18 4.6 Equipment Automated Instrumentation and Monitoring Purchaser and engineer should require in the contract documents, the use of automated monitoring equipment instrumentation to monitor pile installation Electronic and paper printout recording should be made of all acquired data Data should include grout pressure and grout volume (obtained via magnetic flow meter) versus both depth and time and should include angle of pile installation Minimum specified grout ratio or volume per unit pile length should be clearly displayed and recorded to guide the constructor and purchaser during pile installation Equipment should also record auger rotation and hydraulic torque drive pressures Automated instrumentation and monitoring equipment should be calibrated to ensure recording data within +/-3% tolerance of the unit measured whether volume, length, pressure or torque Display device(s) should be supplied for data monitoring by constructor and purchaser during installation of each pile for depth increments not to exceed 2 ft (0.6 m) Printed results and an electronic copy of the data should be provided to the inspector and purchaser immediately following completion of each pile. The electronic data should be furnished in spreadsheet, raw data, and in plot formats Automated instrumentation and monitoring equipment should be provided in accordance with the requirements of this specification for all pile installations except those installed using limited access/low-overhead equipment due to the need to remove auger segments during grouting. Comment: Continuous pile installation electronic monitoring is recommended to provide good QA/QC evidence for each pile. Such monitoring will provide clear documentation of the installation of the pile. Instrument can be arranged to provide immediate feedback to the operator to adjust the installation. Many geotechnical engineers and agencies believe electronic monitoring should be required for all ACIP piles. See DFI TM-ACIP-1, Appendix A for more information Gear Box and Power Unit Purchaser and engineer must be assured that the equipment is of adequate construction to install the ACIP piles. To accomplish the task, the gear box should be rated to provide a minimum of 20,000 ft-lb (27,100 Nm) of torque and apply a reaction of minimum of 4,000 lb (1,800 kg) of down-force (crowd). The down-force may be either dead Process Industry Practices Page 16 of 30

19 weight of components or mechanical force. The power unit should be rated to provide a minimum of 200 hp Equipment provided must be capable of advancing the auger of specified diameter to the specified embedment within the bearing strata. Constructor should be required to prove or demonstrate to the geotechnical engineer specifications and proof that the equipment can and has been used to install piles similar to those specified and in similar conditions. Because encountering subsurface obstructions can cause the unit to rotate and endanger personnel, the contractor should provide procedures or information on restraining the unit. Smaller and lighter equipment used to install low-overhead piles should be evaluated by the engineer on a case-by-case basis Engineer should reserve the ability to require equipment with greater torque and down- force or weight be provided to install ACIP piles in accordance with the contract documents and this Practice Augering Equipment Augers used are continuous flight, hollow stem types with a grout injection port at the bottom of the auger head below the part of the head containing the teeth. The opening should be arranged or equipped to prevent the ingress of soil or water. Some use disposable plugs Auger flighting should be continuous single-helix types without gaps or breaks. Gaps at auger joints may be up to 1 in (25 mm) Augers should have a uniform outer diameter within a tolerance of 3% of that specified in the contract documents. Diameter of the inner pipe should be chosen depending on the soil characteristics and type of continuous flight auger pile desired. The diameter of the inner pipe is often the constructor s decision. It may be desirable to displace some of the soil as the auger passes through using the large diameter grout pipe. Soil displacement often reduces the problem of soil mining Pitch of the auger flighting is often restricted to a spacing of about 9 inches (225 mm) in cohesionless soils to avoid soil mining. Cohesive soils such as clays can have greater flight spacing to aid in moving the soils. Soils with mixed layers should use the tighter spacing Auger penetration rates should be variable to adjust for the soils encountered to reduce the potential for soil mining. Normally penetration rates of 1.5 to 2 revolutions per flight are used in cohesionless soils and 2 to 3 revolutions per flight are used in cohesive soils. Soils with mixed layers should use the slower rate of penetrations per flight Piling leads are used as the guide for the auger head and augers for ACIP pile rigs that hang from a crane Intermediate stabilizing guides should be provided for augers longer than 40 ft (12 m) Piling leads should be prevented from rotating by a stabilizing arm which may also be used for fixing a batter angle. Rotation may also be Process Industry Practices Page 17 of 30

20 prevented by firmly placing the bottom of the leads into the ground or by other means approved by the engineer of record Leads should be clearly marked on both sides at 1-ft (0.3-m) intervals to facilitate measurement of auger penetration. The marks on the leads should be labeled with numerals every 5 ft (1.5 m) such that the inspector can easily determine the final drill depth and the grout return depth. The leads and grout pump should be positioned so the inspector and operator can clearly see the marks, pump pressure, and stroke counter while standing on the grout line Crane or drilling rig should be equipped with controls such that the auger withdrawal can be accomplished at a slow, continuous rate to maintain grout head pressure to avoid gaps or bulges in the pile Equipment furnished should be capable of installing piles at least 10 ft (3 m) longer than that required for bid length piles. Often the requirement is for 20% longer piles to assure that additional capacity is available if conditions warrant. It is also a good practice for the constructor to provide auger sections on hand for at least 20% greater length than the machine capacity If the logs of soil borings indicate that timber logs, cobbles, or other minor obstructions will be encountered before reaching required pile depth, then a rock-cutting bit should be supplied and used Pumping Equipment Pumping equipment used in handling the grout should be adequate to meet the requirements of this Practice and the contract documents and should maintain a homogeneous grout of the required volume and pressure Pump hoppers should be provided with a 3/4-in (20-mm) screen to exclude oversize lumps from creating a blockage Positive displacement pump capable of at least 350-psi (2,400-kPa) displacement pressure at the pump should be provided. Pump should be sized to assure smooth, continuous delivery of grout while limiting pressure fluctuations for the pile size during auger withdrawal Pump pressure gauge should be provided in clear view of the operator and readily accessible to the inspector. Positive pressure should be maintained on the grout at all times during withdrawal Pump should be calibrated on site prior to installation of the first pile and after modifications are made to pumps or other equipment or after a significant change in grout return depth or any time the grout pump is suspected of not operating correctly to accurately determine the volume of grout pumped per stroke. Pump should be capable of delivering grout volumes within 3% of the stated volume. Onsite pump calibration may be completed by recording the number of pump strokes required to fill at least 75% of a 55-gal (200-L) barrel or other accurately known volume container of similar size with grout. Container should be measured and the actual grout volume should be computed when the container is not completely filled at an even number of grout pump strokes. Inspector Process Industry Practices Page 18 of 30

21 should observe the calibration and provide documentation to the engineer of record. Because the computed grout calibration will be low, the grout should not be allowed to overflow the container Digital or mechanical grout pump stroke counter should be provided. Constructor should have at least one spare pump counter available onsite and should maintain the pump stroke counter in operating condition at all times Constructor should position the pump and leads such that the inspector and operator/foreman can clearly see the lead marks, pressure gage, and stroke counter while standing on the grout line near the grout pump. Inspector must remain close to the grout pump to count the number of grout pump strokes placed over each 5-ft (1.5-m) interval Mixing and Grout Transportation Equipment 4.7 Execution Mixing and transportation equipment used in preparing and handling the grout should be adequate to meet the requirements of this Practice and the contract documents and should produce a homogeneous grout of the required consistency Mixing plant equipment may be central mix or transit mix batch plant or an onsite volumetric mix plant. The plant must be calibrated to produce the grout required Transit trucks must be capable of continuously agitating the grout to maintain consistency General Supervision Piling materials, labor, tools, supervision, equipment, and supplies necessary for installing ACIP piles should be furnished in accordance with the contract documents and this Practice Construction should be in accordance with federal standards and instructions of the Occupational Safety and Health Administration (OSHA) and with additional requirements of state or local agencies that have jurisdiction where piles are to be installed To insure continuous installation of each pile, a sufficient quantity of grout to complete a pile should be at the site before pile installation begins. No open holes are permitted in ACIP pile work; otherwise these become drilled shaft piers which are governed by other practices Tolerances Pile centers should be located within a tolerance of +/- 3 in (75 mm) of the locations shown in the contract documents. Structural engineer s pile cap design should account for the tolerance in location Vertical piles should be plumb within 2% to avoid interference with each other and to assure uniform distribution of the loads to the soils below Battered piles should be installed to within 4% of the specified batter for proper load transfer and the reasons stated above. Process Industry Practices Page 19 of 30

22 Reinforcing cages or center bars should have a minimum of 3 in (75 mm) clearance from the wall of the augered hole to provide adequate grout flow and cover Adjacent Piles Piles should normally not be placed within 6 pile diameters, center to center, of adjacent piles containing grout that has set for less than 12 hours Structural engineer of record and geotechnical engineers should determine the allowable spacing and set time before installation of adjacent piles. This determination should consider the lateral strength of the soils and the initial set of the grout Initial grout set for ACIP piles can be field determined using a grout sample taken in a 10 to 20 fluid oz (0.3 to 0.6 L) disposable cup at the time the grout truck arrives on site. Field samples should be set in the shade and checked by the inspector to determine when the grout has set. Inspector should record this information on the pile report Often the constructor will install piles on an alternating pattern to provide time for grout to set. This may take creativity to devise a pattern that installs the piles without affecting adjacent piles and minimizing equipment movement Installation Procedures Length, drilling criteria, and installation procedures of production piles may be modified by the engineer of record from information obtained during the installation of the probe piles, reaction piles, test piles, and the pile load tests Production piles should be installed with the same equipment and identical procedures used for installation of probe piles and test piles Oversight should be provided by an experienced inspector to prevent excessive rotation of the auger, which can cause loss of ground in sands particularly those classified as running sands. Running sands tend to have relatively uniform diameter with low plasticity Drilling should advance at a continuous rate appropriate for the soil conditions until the required depth or refusal is reached If refusal is reached before the required depth, the engineer of record should be notified immediately Auger refusal is defined as a rate of auger penetration of less than 1 ft (0.3 m) per minute of drilling with maximum torque and weight applied to the auger using equipment approved by the engineer of record A plug should be provided in the bottom of the auger during drilling to prevent entry of soil or water into the hollow stem of the auger. Some equipment uses air pressure to avoid soil or water entry, see item at the end of this section When drilling with pressurized air flow through the hollow stem a plug is unnecessary. If the auger tip plugs with soil when drilling with air Process Industry Practices Page 20 of 30