SPECIFICATIONS Rev:

Transcription

1 SPECIFICATIONS Rev: Section Helical Steel Piles 1. General 1.1. Description The work of this section consists of furnishing and installing steel helical piles manufactured by MacLean-Dixie LLC, Birmingham, AL Steel helical piles shall be designed and installed to resist the unfactored design loads as shown on Sheet S-. The geotechnical report for the site dated by is included in this project manual as specification section Related work specified elsewhere: All work as described herein shall be performed in accordance with all applicable safety codes in effect at the time of installation Quality Assurance Installation contractor s qualifications: installation shall be by a MacLean- Dixie Helical Foundation Systems authorized installation contractor. Proof of current certification by MacLean-Dixie Anchoring Systems shall be submitted to the Owner or their representative prior to starting installation upon request of the Owner or their representative All helical piles shall be installed in the presence of a designated representative of the Owner unless the Owner or their representative informs the installation contractor otherwise Welding: procedures shall meet the requirements of AWS Structural Welding Code, D1.1, latest edition. All welders shall be AWS certified Helical pile system shall be ICC-ES listed. The installation contractor shall furnish evidence to the Owner or their representative by means of the ICC-ES Evaluation Report number PFC-5551 if required. 1 of 9

2 1.3. Allowable Tolerances The following tolerances are suggested maximums. The final tolerances for a given project will be established prior to the commencement of the installation of the helical piles and will depend on the specific requirements of the project The centerline of the helical piles shall be within 2 inches of the location as shown on the plans Helical piles shall be within 2 degrees of design alignment The top elevation of the helical pile shall be within +1 inch to -1 inch of plan elevation. 2. Submittals 2.1 Construction Submittals The contractor shall submit working drawings for the helical piles to the Owner or their representative prior to the start of construction for review and approval if required The contractor shall submit detailed construction procedures proposed for use along with a list of the major installation equipment to the Owner or their representative if required The working drawings shall include the following items: a. Helical pile number and location b. Helical pile design load c. Type and size of shaft d. Helical configuration and diameter of helical plates e. Minimum effective installation torque f. Minimum overall length g. Angle of installation of the pile, if other than vertical h. Pile head elevation i. Helical pile attachment to the structure The contractor shall submit shop drawings for the helical pile components, including the corrosion protection and pile top termination device to the Owner or their representative for review and approval The contractor shall submit copies of calibration reports for each torque indicator or torque motor to be used on the project if requested by the Owner or their representative. The calibration tests shall be performed within forty five (45) days of the submitted date. The installation of the 2 of 9

3 helical piles shall not commence until the Owner or their representative has received the calibration reports. The calibration reports shall include, but are not limited to, the following information: a. Name of project and contractor b. Name of testing agency c. Identification (serial number) of device calibrated d. Description of calibrated testing equipment e. Date of calibration Work shall not commence until all submittals have been received and approved by the Owner or their representative. The contractor shall provide the Owner or their representative a reasonable amount of time to review, comment, and return the submittal documents after a complete set has been received. 2.2 Installation Records The contractor shall provide the Owner or their representative copies of all helical pile installation records with 24 hours after each installation is completed. 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 the installation of the piles 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 diameter of helical plates, number and type of extensions sections (manufacturer s SKU numbers) h. Helical piles installation time and any observations i. Total length of installed helical pile j. Cut-off elevation k. Installation angle of the helical pile l. Installation torque at one-foot intervals for at least the final 10 feet of installation m. Comments regarding any interruptions, obstructions, or other installation relevant information n. Rated load capacities. 3 of 9

4 3. Products and Materials 3.1 Solid Shaft Piles (Lead section and extensions) The 1½, 1¾ and 2 inch round cornered square (RCS) solid steel shafts shall be formed from hot-wrought carbon steel and shall confirm to ASTM A576 and the following descriptions: Grade 10V45M or equal, having a minimum yield strength of 70 KSI Grade 1530M, having a minimum yield strength of 90 KSI The round cornered square (RCS) solid steel shafts shall conform to the following torque rating (torsional strength): ,000 ft-lbs for 1½ inch RCS shafts ,000 ft-lbs for 1½ inch RCS high strength shafts ,000 ft-lbs for 1¾ inch RCS shafts ,000 ft-lbs for 2 inch RCS shafts Bolt holes cannot exceed +1/16 inch the nominal bolt diameter 3.2 Pipe Piles (Lead and extensions) The 2-7/8, 3-1/2 and 4-1/2 O.D. pipe piles shall conform to ASTM A500 Grade B The coupling material shall confirm to AISI 8620 or SC1045 per ASTM A The pipe helical pile shall conform to the following torque rating: ,500 ft-lbs for P28 series 2⅞ inch O.D. Schedule 40 Pipe Pile ,000 ft-lbs for P28 series 2⅞ inch O.D. Schedule 80 Pipe Pile ,400 ft-lbs for P35 series 3½ inch O.D. Schedule 40 Pipe Pile ,300 ft-lbs for P35 series 3½ inch O.D. Schedule 80 Pipe Pile ,000 ft-lbs for P45 series 4½ inch O.D. Schedule 40 Pipe Pile ,000 ft-lbs for P45 series 4½ inch O.D. Schedule 80 Pipe Pile ,000 ft-lbs for P8 series 8-5/8 inch O.D wall thickness 4 of 9

5 3.3 Helical Plates Helical plates shall be either ⅜ or ½ inch thick and shall conform to the following specification: ASTM 1011/1018 HSLA 55 or equal The leading edge (leading edge of helix welded to the shaft intersection) of all helices must be in the same plane. 3.4 Bolts/Nuts The sizes and types of bolts and nuts used to connect the helix pile extensions to lead sections or another extension shall conform to the following ASTM specifications: Coupling bolts with ⅝, ¾, or ⅞ inch diameter shall comply with ASTM A325 Grade 5, and shall have a Class C, hotdipped, zinc coating that complies with ASTM A153 Coupling bolts with 1 1/8 diameter on the 2 RCS or ¾ diameter on the 8 5/8, P8 pipe pile shall comply with SAE J429 Grade 8 or ASTM A354 grade BD, and shall have yellow dichromate zinc coating Coupling nuts shall conform to ASTM A563 and shall have a Class C, hot-dipped, zinc coating that complies with ASTM A Connection (Coupling Leads and Extensions) 3.5 Finish Couplings (engagement) for round corner steel (RCS) extensions will be formed as an integral part of the shaft extension material through a forging process except the 2 RCS. For the 2 RCS, the engagement will be a cast coupling Pipe pile couplings must be square engagement with connecting bolts not subjected to shear or bending during installation Couplings for pipe piles shall be cast steel AISI 8620 or SC1045 grade 40/ All other materials, if galvanizing is specified, shall have a Class B1, hot-dipped, galvanized coating, complying with ASTM A Material may also be furnished black (non-galvanized). 5 of 9

6 4.0 Execution 4.1 Site Conditions 4.2 Equipment The contractor shall review the work of all other trades and verify that all said work is completed to the point where helical pile installations may commence without restriction. The contractor shall verify that all helical piles can be installed in accordance with all relevant codes and regulations regarding such items as underground obstructions, utilities, right-of-way limitations, etc. The contactor shall notify the Owner or their representative of any noted discrepancy. The contractor shall not proceed with the installation of helical piles in the area(s) of said discrepancies until the discrepancies have been resolved. All costs associated with unresolved discrepancies shall be the responsibility of the Owner Installation equipment shall be a rotary type, hydraulic power driven torque motor with equal forward and reverse torque capabilities. This equipment shall be capable of continual adjustment of the torque drive unit s revolutions per minute (RPM s) during installation. Percussion drilling equipment will not be allowed. The torque motor shall have a torque capacity at least 15% greater than the torsional strength of steel shaft to be installed Equipment shall be capable of simultaneously applying adequate down pressure and torque. The equipment shall be capable of continuous position adjustment to maintain the proper helical pile alignment. 4.3 Installation Tooling Installing tooling shall consist of a Kelly Bar Adapter (KBA) and drive tools for the helical pile types to be used on the project. All tooling shall be used in accordance with the manufacturer s written installation instructions A torque indicator shall be used during the installation of all helical piles. The torque being applied by the installing units shall be monitored throughout the installation by the contractor. The torque-monitoring device shall either be a part of the installing unit or an independent device in-line with the installing unit. Calibration for either unit shall be available for review by the owner. Torque indicators shall: 6 of 9

7 a. Be capable of providing continuous measurement of the applied torque throughout the installation. b. Be capable of torque measurements in increments of at least 500 ft-lbs. c. 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. Torque indicators that measure torque as a function of hydraulic pressure shall be calibrated at normal operating temperatures. d. Be recalibrated, if in the opinion of the Owner, their representative, and/or the contractor, reasonable doubt exists as to the accuracy of the torque measurements. 4.4 Installation procedures The helical pile 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 is established. Engage and advance the helical pile lead and extension sections in a smooth, continuous manner with the rate of pile rotation in the range of 5 to 20 RPM s. Extension sections shall be used to obtain the required minimum overall length and installation torque as shown on the working drawings. The coupling bolt(s) and nut(s) used to connection sections shall be torqued to 40 ft-lbs Apply sufficient down pressure to uniformly advance the helical sections at a rate per revolution approximately equal to the pitch of the helices. The pitch of the helices is approximately 3 inches for standard RCS and pipe helical piles. The rate of rotation and magnitude of down pressure must be adjusted for different soil conditions and depths in order to maintain the penetration rate. 4.5 Termination Criteria The torque as measured during the installation shall not exceed the torque rating (torsional strength) of the steel helical lead and extension shaft sections The minimum installation torque and minimum overall length criteria as shown on the working drawings shall be satisfied prior to terminating the installation of the helical pile The top most helix shall be located not less than 5 times its diameter below the bottom of the foundation for deep foundation behavior 7 of 9

8 considerations. However, other site specific conditions, such as, frost, fill, soft compressible soils, expansive soils, etc. may warrant a greater minimum depth If the torsional strength rating of the helical pile and/or installing equipment has been reached prior to satisfying the minimum length required, the installation contractor shall have the following options: Terminate the installation at the length obtained with the approval by and acceptance of the Owner or their representative, or Remove the existing helical pile and install a new pile with fewer and/or smaller diameter helical plates. This new pile configuration shall be subject to review by and acceptance of the Owner or their representative. If the new pile is installed at the same location as the original pile, then the top most helix of the new helical pile shall be terminated at least three times the diameter of top most helix of the new pile beyond the termination depth of the original pile If the minimum installation torque as shown on the working drawings is not achieved at the minimum overall length and there is no maximum overall length constraint, the installation contractor shall have the following options: Install the helical pile deeper using additional extension sections, or Remove the existing helical pile and install a new pile with additional and/or larger diameter helical plates. This new pile configuration shall be subject to review by and acceptance of the Owner or their representative. If the new pile is installed at the same location as the original pile, then the top most helix of the new helical pile shall be terminated at least three times the diameter of top most helix of the new pile beyond the termination depth of the original pile, or Derate the load capacity of the helical pile and install additional helical pile(s). The derated capacity and additional helical pile location(s) shall be subject to the review by and acceptance of the Owner or their representative If the helical pile reaches refusal or is deflected by a subsurface obstruction, the installation shall be terminated and the helical pile removed. The obstruction shall be removed, if feasible, and the helical pile shall be reinstalled. If the obstruction cannot be removed, the helical 8 of 9

9 pile shall be installed at an adjacent location subject to review by and acceptance of the Owner or their representative If the torsional strength rating of the helical pile shaft and/or installation equipment has been reached prior to the proper positioning of the elevation of the top of the helical pile, the contractor may remove the last extension and replace it with a shorter length extension. If it is not feasible to remove the last extension, the contractor may cut said extension to the proper elevation. The contractor shall not reverse (back-out) the helical pile to facilitate extension removal The average torque for the last 3 feet of penetration shall be used as a basis of comparison with the minimum recommended installation torque as shown on the working drawings. The average torque is the average of the last 3 torque readings recorded at one-foot intervals. This average torque is intended solely as an indication of the helical pile s ultimate bearing capacity The contractor shall maintain a written installation record for each helical pile. This record shall include information as noted in Section 2.2 Installation Records. End of Specification 9 of 9