36C25622R0094 316500 Helical Piles.doc

REPLACE AHU #104 AND DUCTWORK BLDG. 7

DEPARTMENT OF VETERANS AFFAIRS HEALTH CARE SYSTEM-ALEXANDRIA, LA

PROJECT NO.: 502-19-107

SECTION 31 65 00

HELICAL PILES

PART 1 - GENERAL

1.1 PURPOSE OF SPECIFICATION

The purpose of this specification is to detail the furnishing of all designs, materials, tools, equipment, labor and supervision, and installation techniques necessary to install Helical Piles as detailed on the drawings, including connection details. This shall include provisions for load testing that may be part of the scope of work.

1.2 SCOPE OF WORK

This work consists of furnishing all necessary engineering and design services, supervision, labor, tools, materials, and equipment to perform all work necessary to install the Helical Piles per the specifications described herein, and as shown on the drawings. The Contractor shall install a Helical Pile that will develop the load capacities as detailed on the drawings. This also includes provisions for load testing to verify Helical Pile capacity and deflection, if part of the scope of work.

Table-1. Tasks and Responsibilities to be allocated for Helical Pile Work The Helical Pile contractor shall be responsible for the following:

TASK

1.3 QUALIFICATIONS OF THE HELICAL PILE CONTRACTOR

The Helical Pile Contractor shall be experienced in performing design and construction of Helical Piles and shall furnish all materials, labor, and supervision to perform the work. The Contractor shall be trained in the proper methods of design and installation of Helical Piles.

The Helical Pile Contractor shall not sublet the whole or any part of the contract without the express written permission of the Government.

1.4 DEFINITIONS

A. Contractor: The person/firm responsible for performing the Helical Pile work.

Coupling: Central steel shaft connection means formed as integral part of the plain extension shaft material. For Helical Piles, couplings are internal or external sleeves, or hot upset forged sockets.

Coupling Bolt(s): High strength, structural steel fasteners used to connect Helical Pile segments together. For Type SS segments, the coupling bolt transfers axial load. For Type RS segments, the coupling bolts transfer both axial and torsional forces.

Helix Plate: Generally round steel plate formed into a ramped spiral. The helical shape provides the means to install the helical pile, plus the plate transfers load to soil in end bearing. Helix plates are available in various diameters and thickness.

B. Helical Pile: A bearing type foundation element consisting of a lead or starter section, helical extension (if so, required by site conditions), plain extension section(s), and a pile cap. A.k.a. helical screw pile, screw pile, helical screw foundation.

Installation Torque(T) : The resistance generated by a Helical Pile when installed into soil. The installation resistance is a function of the soil type, and size and shape of the various components of the Helical Pile.

C. Lead Section: The first Helical Pile foundation component installed into the soil, consisting of single or multiple helix plates welded to a central steel shaft. A.k.a. Starter Section.

D. Pile Cap: Connection means by which structural loads are transferred to the Helical Pile. The type of connection varies depending upon the requirements of the project and type of Helical Pile material used.

E. Plain Extension: Central steel shaft segment without helix plates. It is installed following the installation of the lead section or helical extension (if used). The segments are connected with integral couplings and bolts. Plain extensions are used to extend the helix plates beyond the specified minimum depth and into competent load bearing stratum.

F. Safety Factor: The ratio of the ultimate capacity to the working or design load used for the design of any structural element.

G. Square Shaft (SS): Solid steel, round-cornered-Square central Shaft elements ranging in size from 1-1/4" to 2-1/4". A.k.a. Type SQ.

H. Torque Strength Rating: The maximum torque energy that can be applied to the helical pile foundation during installation in soil, a.k.a. allowable, or safe torque.

1.5 ALLOWABLE TOLERANCES

The tolerances quoted in this section are suggested maximums. The actual values established for a particular project will depend on the structural application.

A. Centerline of Helical Piles shall not be more than 3 inches from indicated plan location.

B. Helical Pile plumbness shall be within 2( of design alignment.

C. Top elevation of Helical Pile shall be within +1 inch to –2 inches of the design vertical elevation.

1.6 QUALITY ASSURANCE

A. Helical Piles shall be installed by contractor with a minimum of 10 years’ experience in Helix Foundations. These Contractors shall have satisfied the certification requirements relative to the technical aspects of the product and installation procedures as therein specified. Certification documents shall be provided upon request to the Government or their representative.

B. The Contractor shall employ an adequate number of skilled workers who are experienced in the necessary crafts and who are familiar with the specified requirements and methods needed for proper performance of the work of this specification.

C. All Helical Piles shall be installed in the presence of a designated representative of the Government unless said representative informs the Contractor otherwise. The designated representative shall have the right of access to any and all field installation records and test reports.

D. Provides a standard three-year warranty on materials and workmanship of the product.

E. Design of Helical Piles shall be performed by an entity as required in accordance with IBC 2012 code requirements or established local practices. This design work may be performed by a licensed professional engineer.

1.7 DESIGN CRITERIA

A. Helical Piles shall be designed to meet the specified loads and acceptance criteria as shown on the drawings. The calculations and drawings required from the Contractor or Engineer shall be submitted to the Government for review and acceptance in accordance to Section 3.1 “Construction Submittals”.

B. The allowable working load on the Helical Piles shall not exceed the following values:

1. For compression loads:

Pallowc = 0.4 * fyshaft * Ashaft Where:

Pallowc = allowable working load in compression (kip) fyshaft = minimum yield strength of central steel shaft (ksi)

Ashaft = area of central steel shaft (with corrosion allowance if required) (in.2)

C. The ultimate structural capacity shall be determined as:

1. For compression loads:

Pultc = fyshaft * Ashaft

Where:

Pultc = ultimate structural capacity in compression (kip) fyshaft = minimum yield strength of central steel shaft (ksi)

Ashaft = area of central steel shaft (with corrosion allowance if required) (in.2) D. For tension loads:

Pultt = Sut

Where:

Pultt = Ultimate structural capacity in tension (kip)

Sut = Minimum ultimate tensile strength of central steel shaft (kip)

E. The overall length and installed torque of a Helical Pile shall be specified such that the required in-soil capacity is developed by end-bearing on the helix plate(s) in an appropriate strata(s).

It is recommended that the theoretical end-bearing capacity of the helix plates be determined using HeliCAP® Engineering Software or equal commercially available software. The Government shall determine the allowable response to axial loads.

F. Lateral Load and Bending: Helical Piles will be subject to lateral or base shear loads as indicated on the plans, the bending moment from said loads shall be determined using lateral load analysis program such as LPILE or equal commercially available software. The combined bending and axial load factor of safety of the Helical Pile shall be as determined by the Government.

G. Critical Buckling Load: Where Helical Piles are installed into low strength soil, the critical buckling load shall be determined using lateral load analysis program such as LPILE or equal commercially available software, or various other methods.

H. The Helical Pile attachment (pile cap) shall distribute the design load (DL) to the concrete foundation such that the concrete bearing stress does not exceed those in the ACI Building Code and the stresses in the steel plates/welds does not exceed AISC allowable stresses for steel members.

I. Corrosion Protection

All install components shall be galvanized.

1.9. GROUND CONDITIONS

The Geotechnical logs of soil borings attached in the contract documents shall be considered to be representative of the in-situ subsurface conditions likely to be encountered on the project site. Said Geotechnical borings shall be used as the basis for Helical Pile design using generally accepted engineering judgement and methods.

PART 2 - SUBMITTALS

2.1 CONSTRUCTION SUBMITTALS

A. The Contractor or Engineer shall prepare and submit to the Government, for review and approval, shop drawings and design calculations for Helical Piles intended for use. All submittals shall be signed and sealed by a Registered Professional Engineer. The Contractor shall submit a detailed description of the construction procedures proposed for use to the Government for review. The Contractor shall submit a detailed description of the construction procedures proposed for use to the Government for review. This shall include a list of major equipment to be used.

B. The Shop Drawings shall include the following:

1. Helical Pile number, location, and pattern by assigned identification number

2. Helical Pile design load

3. Type and size of central steel shaft

4. Helix configuration (number and diameter of helix plates)

5. Minimum effective installation torque

6. Minimum overall length

7. Inclination of Helical Pile

8. Cut-off elevation

9. Helical Pile attachment to structure relative to grade beam, column pad, pile cap, etc.

C. The Contractor shall submit shop drawings for all Helical Pile components, including corrosion protection and pile top attachment to the Government for review and approval. This includes Helical Pile lead/starter and extension section identification (manufacturer’s catalog numbers).

D. If required, the Contractor shall submit certified mill test reports for the central steel shaft, as the material is delivered, to the Government for record purposes. The ultimate strength, yield strength, % elongation, and chemistry composition shall be provided.

E. The Contractor shall submit plans for pre-production (optional) and production testing for the Helical Piles to the Government for review and acceptance prior to beginning load tests. The purpose of the test is to determine the load versus displacement response of the Helical Pile and provide an estimation of ultimate capacity.

F. The Contractor shall submit to the Government copies of calibration reports for each torque indicator or torque motor, and all load test equipment to be used on the project. The calibration tests shall have been performed within forty-five (45) working days of the date submitted. Helical Pile installation and testing shall not proceed until the Government has received the calibration reports. These calibration reports shall include, but are not limited to, the following information:

1. Name of project and Contractor

2. Name of testing agency

3. Identification (serial number) of device calibrated

4. Description of calibrated testing equipment

5. Date of calibration

6. Calibration data

G. Work shall not begin until all the submittals have been received and approved by the Government. The Contractor shall allow the Government a reasonable time to review, comment, and return the submittal package after a complete set has been received. All costs associated with incomplete or unacceptable submittals shall be the responsibility of the Contractor.

2.2 INSTALLATION RECORDS

The Contractor shall provide the Government copies of Helical Pile installation records within 24 hours after each installation is completed. Records shall be prepared in accordance with the specified division of responsibilities as noted in Table-1. Formal copies shall be submitted on a weekly basis. These installation records shall include, but are not limited to, the following information.

A. Name of project and Contractor

B. Name of Contractor’s supervisor during installation

C. Date and time of installation

D. Name and model of installation equipment

E. Type of torque indicator used

F. Location of Helical Pile by assigned identification number

G. Actual Helical Pile type and configuration – including lead section (number and size of helix plates), number and type of extension sections (manufacturer’s SKU numbers)

H. Helical Pile installation duration and observations

I. Total length of installed Helical Pile

J. Cut-off elevation

K. Inclination of Helical Pile

L. Installation torque at one-foot intervals for the final 10 feet

M. Comments pertaining to interruptions, obstructions, or other relevant information

N. Rated load capacities

2.3 TEST REPORTS

The Contractor shall provide the Government copies of field test reports within 24 hours after completion of the load tests. Records shall be prepared in accordance with the specified division of responsibilities as noted in Table-1. Formal copies shall be submitted within a reasonable amount of time following test completion. These test reports shall include, but are not limited to, the following information (note Section 6 – Helical Pile Load Tests).

A. Name of project and Contractor

B. Name of Contractor’s supervisor during installation

C. Name of third-party test agency, if required

D. Date, time, and duration of test

E. Location of Helical Pile by assigned identification number

F. Type of test (i.e. tension or compression)

G. Description of calibrated testing equipment and test set-up

H. Actual Helical Pile type and configuration – including lead section, number, and type of extension sections (manufacturer’s SKU numbers)

I. Steps and duration of each load increment

J. Cumulative pile-head movement at each load step

K. Comments pertaining to test procedure, equipment adjustments, or other relevant information

L. Signed by third party test agency rep. or registered professional engineer.

2.4 CLOSEOUT SUBMITTALS

A. Warranty: Warranty documents specified herein

1. Project Warranty: Refer to Conditions of the Contract for project warranty provisions

2. Warranty Period: 5 years commencing on date of Substantial Completion

3. Manufacturer’s Warranty: Submit, for Government’s Acceptance, manufacturer’s standard warranty document executed by authorized company official. Manufacturer’s warranty is in addition to, and not a limitation of, other rights the Government may have under Contract Document.

PART 3 - PRODUCTS AND MATERIALS

2.5 CENTRAL STEEL SHAFT:

The central steel shaft, consisting of lead sections, helical extensions, and plain extensions, shall be Type SS (Square Shaft) or RS (Round Shaft) or a combination of the two (SS to RS Combo Pile) as manufactured by CHANCE Civil Construction (Centralia and Independence, MO).

A. SS5 1-1/2" Material: Shall be hot rolled Round-Cornered-Square (RCS) solid steel bars meeting dimensional and workmanship requirements of ASTM A29. The bar shall be modified medium carbon steel grade (similar to AISI 1044) with improved strength due to fine grain size.

1. Torque strength rating = 5,500 ft-lb

2. Minimum yield strength = 70 ksi

B. SS125 1-1/4"; SS1375 1-3/8"; SS150 1-1/2"; SS175 1-3/4; SS200 2"; SS225 2-1/4" Material: Shall be hot rolled Round-Cornered-Square (RCS) solid steel bars meeting the dimensional and workmanship requirements of ASTM A29. The bar shall be High Strength Low Alloy (HSLA), low to medium carbon steel grade with improved strength due to fine grain size.

1. Torque strength rating: SS125 = 4,000 ft-lb; SS1375 = 5,500 ft-lb; SS150 = 7,000 ft-lb; SS175 = 11,000 ft-lb; SS200 = 16,000 ft-lb; SS225 = 23,000 ft-lb

2. Minimum yield strength = 90 ksi

C. Type RS2875 2-7/8" OD Material: Structural steel tube or pipe, welded or seamless, in compliance with ASTM A500 or A513. Wall thickness is 0.165", 0.203" or 0.262".

1. Torque strength rating: RS2875.165 = 4,500 ft-lb; RS2875.203 = 5,500 ft-lb; RS2875.262 = 7,500 ft-lb.

2. Minimum yield strength = 50 ksi

D. Type RS3500 3-1/2" OD Material: Shall be structural steel tube or pipe, seamless or straight-seam welded, per ASTM A53, A252, ASTM A500, or ASTM A618. Wall thickness is 0.300" (schedule 80).

1. Torque strength rating = 13,000 ft-lb

2. Minimum yield strength = 50 ksi

E. Type RS4500 4-1/2" OD Material: Shall be structural steel tube or pipe, seamless or straight-seam welded, per ASTM A500 or A513. Wall thickness is 0.337" (schedule 80).

1. Torque strength rating = 23,000 ft-lb

2. Minimum yield strength = 50 ksi

F. SS to RS2875 Combo Pile Material: Shall be Type SS and RS2875 material as described above with a welded adapter for the transition from SS to RS2875.

G. SS to RS3500 Combo Pile Material: Shall be Type SS and RS3500 material as described above with a welded adapter for the transition from SS to RS3500.

H. SS to RS4500 Combo Pile Material: Shall be Type SS and RS4500 material as described above with a welded adapter for the transition from SS to RS4500.

2.6 HELIX BEARING PLATE:

Helix Bearing Plate shall be hot rolled carbon steel sheet, strip, or plate formed on matching metal dies to true helical shape and uniform pitch. Bearing plate material shall conform to the following ASTM specifications.

A. SS5 Material: Per ASTM A572, or A1018, or A656 with minimum yield strength of 50 ksi. Plate thickness is 3/8".

B. SS125 and SS1375 Material: Per ASTM A572 with minimum yield strength of 50 ksi. Plate thickness is 3/8" or ½".

C. SS150 and SS175 Material: Per ASTM A656 or A1018 with minimum yield strength of 80 ksi. Plate thickness is 3/8" or ½".

D. SS200 and SS225 Material: Per ASTM A656 or A1018 with minimum yield strength of 80 ksi. Plate thickness is ½".

E. RS2875 Material: Per ASTM A36, or A572, with minimum yield strength of 36 ksi. Plate thickness is 3/8" or ½".

F. RS3500 Material: Per ASTM A36, or A572, or A1018, or A656 depending on helix diameter, per the minimum yield strength requirements cited above. Plate thickness is 3/8" or ½".

G. RS4500 Material: Per ASTM A572 with minimum yield strength of 50 ksi. Plate thickness is ½".

2.7 BOLTS:

The size and type of bolts used to connect the central steel shaft sections together shall conform to the following ASTM specifications.

A. SS125 1-1/4" Material: 5/8" diameter bolt (2 per coupling) per SAE J429 Grade 8.

B. SS1375 1-3/8" Material: ¾" diameter bolt (2 per coupling) per SAE J429 Grade 8.

C. SS5 and SS150 1-1/2" Material: ¾" diameter bolt per ASTM A320 Grade L7 or ASTM A325.

D. SS175 1-3/4" Material: 7/8" diameter bolt per ASTM A193 Grade B7.

E. SS200 2" Material: 1-1/8" diameter bolt per ASTM A193 Grade B7.

F. SS225 2-1/4" Material: 1-1/4" diameter bolt per ASTM A193 Grade B7.

G. RS2875 2-7/8" OD Material: ¾" diameter bolts (2 or 4 per coupling) per SAE J429 Grade 5 or 8.

H. RS3500 3-1/2" OD Material: ¾" diameter bolts (3 or 4 per coupling) per SAE J429 Grade 5 or 8.

I. RS4500 4-1/2" OD Material: ¾" diameter bolts (4 per coupling) per SAE J429 Grade 8.

2.8 COUPLINGS:

For type SS5, SS150, SS175, SS200, and SS225 material, the coupling shall be formed as an integral part of the plain and helical extension material as hot upset forged sockets. For Type SS125 and SS1375 material, the coupling shall be a cast steel sleeve with two holes for connecting shaft sections together.

For Type RS2875, RS3500, and RS4500 material, the couplings shall either be formed as an integral part of the plain and helical extension material as hot forge expanded sockets, or as internal sleeve wrought steel connectors. The steel connectors can be either tubing or solid steel bar with holes for connecting shaft sections together.

2.9 PLATES, SHAPES, OR PILE CAPS:

Depending on the application, the pile cap shall be a welded assembly consisting of structural steel plates and shapes designed to fit the pile and transfer the applied load. Structural steel plates and shapes for HELICAL PILE top attachments shall conform to ASTM A36 or ASTM A572 Grade 50.

2.10 CORROSION PROTECTION

A. Galvanization: All material shall be hot-dipped galvanized in accordance with ASTM A153 after fabrication.

PART 4 - EXECUTION

2.11 Site Conditions

A. Prior to commencing Helical Pile installation, the Contractor shall inspect the work of all other trades and verify that all said work is completed to the point where Helical Piles may commence without restriction.

B. The Contractor shall verify that all Helical Piles may be installed in accordance with all pertinent codes and regulations regarding such items as underground obstructions, right-of-way limitations, utilities, etc.

C. In the event of a discrepancy, the Contractor shall notify the Government.

2.12 INSTALLATION EQUIPMENT

A. Shall be rotary type, hydraulic power-driven torque motor with clockwise and counterclockwise rotation capabilities. The torque motor shall be capable of continuous adjustment to revolutions per minute (RPM’s) during installation. Percussion drilling equipment shall not be permitted. The torque motor shall have torque capacity 15% greater than the torsional strength rating of the central steel shaft to be installed.

B. Equipment shall be capable of applying adequate down pressure (crowd) and torque simultaneously to suit project soil conditions and load requirements. The equipment shall be capable of continuous position adjustment to maintain proper Helical Pile alignment.

2.13 INSTALLATION TOOLING

A. A torque indicator shall be used during Helical Pile installation. The torque indicator can be an integral part of the installation equipment or externally mounted in-line with the installation tooling.

1. Shall be capable of providing continuous measurement of applied torque throughout the installation.

2. Shall be capable of torque measurements in increments of at least 500 ft-lb

3. Shall be calibrated prior to pre-production testing or start of work. Torque indicators which are an integral part of the installation equipment, shall be calibrated on-site. Torque indicators which are mounted in-line with the installation tooling, shall be calibrated either on-site or at an appropriately equipped test facility. Indicators that measure torque as a function of hydraulic pressure shall be calibrated at normal operating temperatures.

4. Shall be re-calibrated, if in the opinion of the Government and/or Contractor reasonable doubt exists as to the accuracy of the torque measurements.

2.14 INSTALLATION PROCEDURES

A. Central Steel Shaft: (Lead and Extension Sections)

1. The Helical Pile installation technique shall be such that it is consistent with the geotechnical, logistical, environmental, and load carrying conditions of the project.

2. The lead section shall be positioned at the location as shown on the working drawings. Battered Helical Piles can be positioned perpendicular to the ground to assist in initial advancement into the soil before the required batter angle shall be established. The Helical Pile sections shall be engaged and advanced into the soil in a smooth, continuous manner at a rate of rotation of 5 to 20 RPM’s. Extension sections shall be provided to obtain the required minimum overall length and installation torque as shown on the working drawings. Connect sections together using coupling bolt(s) and nut torqued to 40 ft-lb.

3. Sufficient down pressure shall be applied to uniformly advance the Helical Pile sections approximately 3 inches per revolution. The rate of rotation and magnitude of down pressure shall be adjusted for different soil conditions and depths.

2.15 TERMINATION CRITERIA

A. The torque as measured during the installation shall not exceed the torsional strength rating of the central steel shaft.

B. The minimum installation torque and minimum overall length criteria as shown on the working drawings shall be satisfied prior to terminating the Helical Pile installation.

C. If the torsional strength rating of the central steel shaft and/or installation equipment has been reached prior to achieving the minimum overall length required, the Contractor shall have the following options:

1. Terminate the installation at the depth obtained subject to the review and acceptance of the Government, or:

2. Remove the existing Helical Pile and install a new one with fewer and/or smaller diameter helix plates. The new helix configuration shall be subject to review and acceptance of the Government. If re-installing in the same location, the top-most helix of the new Helical Pile shall be terminated at least (3) three feet beyond the terminating depth of the original Helical Pile.

D. If the minimum installation torque as shown on the working drawings is not achieved at the minimum overall length, and there is no maximum length constraint, the Contractor shall have the following options:

1. Install the Helical Pile deeper using additional extension sections, or:

2. Remove the existing Helical Pile and install a new one with additional and/or larger diameter helix plates. The new helix configuration shall be subject to review and acceptance of the Government. If re-installing in the same location, the top-most helix of the new Helical Pile shall be terminated at least (3) three feet beyond the terminating depth of the original Helical Pile.

3. De-rate the load capacity of the Helical Pile and install additional Helical Pile(s). The de-rated capacity and additional Helical Pile location shall be subject to the review and acceptance of the Government.

E. If the Helical Pile is refused or deflected by a subsurface obstruction, the installation shall be terminated, and the pile removed. The obstruction shall be removed, if feasible, and the Helical Pile re-installed. If the obstruction can’t be removed, the Helical Pile shall be installed at an adjacent location, subject to review and acceptance of the Government.

F. If the torsional strength rating of the central steel shaft and/or installation equipment has been reached prior to proper positioning of the last plain extension section relative to the final elevation, the Contractor may remove the last plain extension and replace it with a shorter length extension. If it is not feasible to remove the last plain extension, the Contractor may cut said extension shaft to the correct elevation. The Contractor shall not reverse (back-out) the Helical Pile to facilitate extension removal.

G. The average torque for the last three feet of penetration shall be used as the basis of comparison with the minimum installation torque as shown on the working drawings. The average torque shall be defined as the average of the last three readings recorded at one-foot intervals.

PART 6 - HELICAL PILE LOAD TESTS

2.16 PRE-PRODUCTION TESTS

Load tests shall be performed to verify the suitability and capacity of the proposed Helical Pile, and the proposed installation procedures prior to installation of production helical piles. Two sacrificial test helical piles shall be constructed immediately prior to the start of work on the production piles.

Pre-production Helical Pile installation methods, procedures, equipment, and overall length shall be identical to the production Helical Piles to the extent practical except where approved otherwise by the Government.

The Contractor shall submit for review and acceptance the proposed Helical Pile load testing procedure. The pre-production test proposal shall be in general conformance with ASTM D1143 and/or D-3689, and shall provide the minimum following information:

A. Type and accuracy of load equipment

B. Type and accuracy of load measuring equipment

C. Type and accuracy of pile-head deflection equipment

D. General description of load reaction system, including description of reaction anchors

E. Calibration report for complete load equipment, including hydraulic jack, pump, pressure gauge, hoses, and fittings.

F. If the pre-production test fails to meet the design requirements, the Contractor shall modify the Helical Pile design and/or installation ethods and retest the modified anchor, as directed by the Government.

2.17 LOAD TEST EQUIPMENT

A. The load test equipment shall be capable of increasing or decreasing the applied load incrementally. The incremental control shall allow for small adjustments, which may be necessary to maintain the applied load for a sustained, hold period.

B. The reaction system shall be designed so as to have sufficient strength and capacity to distribute the test loads to the ground. It should also be designed to minimize its movement under load and to prevent applying an eccentric load to the pile head. Test loads are normally higher than the design loads on the structure. The direction of the applied load shall be collinear with the Helical Pile at all times.

C. Dial gauge(s) shall be used to measure Helical Pile movement. The dial gauge shall have an accuracy of at least +/-0.001-in. and a minimum travel sufficient to measure all Helical Pile movements without requiring resetting the gauge. The dial gauge shall be positioned so its stem is parallel with the axis of the Helical Pile. The stem may rest on a smooth plate located at the pile head. Said plate shall be positioned perpendicular to the axis of the Helical Pile. The dial gauge shall be supported by a reference apparatus to provide an independent fixed reference point. Said reference apparatus shall be independent of the reaction system and shall not be affected by any movement of the reaction system.

D. The load test equipment shall be re-calibrated, if in the opinion of the Government and/or Contractor reasonable doubt exists as to the accuracy of the load or deflection measurements.

2.18 TESTING PROGRAM

A. The hydraulic jack shall be positioned at the beginning of the test such that the unloading and repositioning of the jack during the test shall not be required. The jack shall also be positioned co-axial with respect to the pile-head so as to minimize eccentric loading. The hydraulic jack shall be capable of applying a load not less than two times the proposed design load (DL). The pressure gauge shall be graduated in 100 psi increments or less. The stroke of the jack shall not be less than the theoretical elastic shortening of the total Helical Pile length at the maximum test load.

B. An alignment load (AL) shall be applied to the Helical Pile prior to setting the deflection measuring equipment to zero or a reference position. The AL shall be no more than 10% of the design load (i.e., 0.1 DL). After AL is applied, the test set-up shall be inspected carefully to ensure it is safe to proceed.

C. Axial compression or tension load tests shall be conducted by loading the Helical Pile in stepwise fashion as shown in Table-3 to the extent practical. Pile-head deflection shall be recorded at the beginning of each step and after the end of the hold time. The beginning of the hold time shall be defined as the moment when the load equipment achieves the required load step.

D. Test loads shall be applied until continuous jacking is required to maintain the load step or until the test load increment equals 200% of the design load (DL) (i.e., 2.0 DL), whichever occurs first. The observation period for this last load increment shall be 10 minutes. Displacement readings shall be recorded at 1, 2, 3, 4, 5 and 10 minutes (load increment maxima only).

E. The applied test load shall be removed in four approximately equal decrements. The hold time for these load decrements shall be 1 minute, except for the last decrement, which shall be held for 5 minutes.

2.19 ACCEPTANCE CRITERIA FOR HELICAL PILE VERIFICATION LOAD TESTS

Both of the following criteria must be met for approval:

A. The Helical Pile shall sustain the compression design capacities (1.0 LOAD) with no more than ½ in. (mm) total vertical movement of the pile-head as measured relative to the top of the Helical Pile prior to the start of testing.

B. Failure does not occur at the 2.0 LOAD maximum compression and tension test loads. The failure load shall be defined by one of the following definitions – whichever results in the lesser load:

1. The point at which the movement of the Helical Pile tip exceeds the elastic compression/tension of the pile shaft by 0.08 B, where B is defined as the diameter of the largest helix. (Note that tension loads are limited to the minimum ultimate tensile strength of the coupling joint(s) of the central steel shaft. It is recommended to use the minimum ultimate tensile strengths as published by Chance Civil Construction (shown in Table-1A & 1B of the Appendix).

2. The point at which the slope of the load versus deflection (at end of increment) curve exceeds 0.05 inches/kip.

The Contractor shall provide the Government copies of field test reports confirming Helical Pile configuration and construction details within 24 hours after completion of the load tests. Formal copies shall be submitted as per Section 3.3. This written documentation will either confirm the load capacity as required on the working drawings or propose changes based upon the results of the pre-production tests.

When a Helical Pile fails to meet the acceptance criteria, modifications shall be made to the design, the construction procedures, or both. These modifications include, but are not limited to, de-rating the Helical Pile load capacity, modifying the installation methods and equipment, increasing the minimum effective installation torque, changing the helix configuration, or changing the Helical Pile material (i.e., central steel shaft). Modifications that require changes to the structure shall have prior review and acceptance of the Government. The cause for any modifications of design or construction procedures shall be decided in order to determine any additional cost implications.

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