00963.30 939 Section 00963 - Signal Support Drilled Shafts
Description
00963.00Scope - This Work consists of excavating and constructing drilled, cast -in-place, reinforced
concrete shafts for signal supports according to the Specifications.
00963.01Definitions :
Drilled Shafts - Reinforced concrete sections, cast -in-place against in situ Soil, Rock or a casing.
Temporary Casing - Casing installed to facilitate D rilled Shaft construction only and removed during or after concrete placement.
00963.02Subsurface Investigation - The Soils and Geological Exploration Logs are available for
review through the Engineer's office. The data shown for each test boring or test pit applies only to that particular boring or test pit. Subsurface conditions may vary between borings or test pits. Core samples and laboratory test results, if obtained and performed for the Project, are available for review by contacting the Engineer.
Materials
00963.10Materials - Furnish Materials meeting the following requirements:
Furnish Commercial Grade Concrete meeting the requirements of Section 00440 except provide the mixture with a slump of 8 1/2 inches ± 1 1/2 inches.
00963.13Steel Casing - Furnish Temporary Casing meeting the requirements of ASTM A252 or
ASTM A36. Test each heat of steel at 40 °F with a minimum absorbed energy requirement of 15 foot pounds. Use casing of sufficient strength to resist handling, transportation and installation stresses and the external stresses of the subsurface materials. Ensure that the casing is clean and water tight prior to placement in the D rilled Shaft excavation. Use casing with an outside diameter not less than the specified D rilled Shaft diameter.
00963.19Quality Control - Provide quality control according to 00512.19
Labor
00963.30Personnel Qual ifications - Perform the D rilled Shaft construction Work using a company
and personnel experienced in D rilled Shaft construction work. Submit a list to the Engineer for approval identifying the on-site supervisors and drill rig operators assigned to the Project and the companies experience relevant to the Project . Experience shall be relevant to the anticipated subsurface materials, groundwater conditions, shaft size, depth, and all special construction techniques required. Before the preconstruction conference, provide the following information to verify the firm's experience and the qualifications of personnel scheduled to perform the D rilled Shaft construction:
• Submit a project reference list of at least three separate foundation projects, successfully completed in the last 5 years, with Drilled Shafts of diameters and depths equal to or larger than those shown in the Plans and in ground conditions similar to those indicated. Include a brief description of each project and the owner's contact person' s name and current phone number for each project listed. 00963.40 940 • On-site supervisors shall have at least 2 years ' experience in supervising construction of D rilled Shaft foundations of similar diameter and depth and scope to those shown in the Plans and in similar geotechnical conditions to those described in the geotechnical report. Experience shall include the direct supervisory responsibility for the on-site construction operations. • Drill operators shall have at least 1 year experience in the construction of D rilled Shaft foundations.
The Engineer will respond within 21 Calendar Days after receipt of the submittal. Do not begin Work on any D rilled Shafts until the qualifications have been approved. The Engineer may suspend the Drilled Shaft construction if the Contractor substitutes unapproved personnel during construction. Submit requests for substitution of either on- site supervisors or drill operators to the Engineer, who will have 7 Calendar Days to respond to each request. Additional costs resulting from the suspension of Work due to the changing of personnel will be the Contractor's responsibility, and no adjustment in Contract Time resulting from the suspension of Work will be allowed.
Construction
00963.40Submittals - Provide the following submittals to the Agency for review and approval:
construction, submit the following:
• The sequence of D rilled Shaft construction as it relates to the overall con struction plan. • A review of Equipment suitability based on the Contractor's understanding of the site subsurface conditions. Include a project history of the drilling Equipment that demonstrates the successful use of the Equipment for Drilled Shafts of equal or greater size in similar subsurface conditions. • Details of shaft excavation methods, including proposed drilling methods and a disposal plan for excavated material. Include details of methods used to perform final cleaning of the excavation. Includ e details of the methods and M aterials used to fill or eliminate all voids between the plan shaft diameter and excavated shaft diameter, or between the casing and surrounding Soil, if permanent casing is specified. Include a disposal plan for any water or contaminated concrete expelled from the top of the shaft if applicable. • Details of the proposed methods for ensuring D rilled Shaft stability during excavation and concrete placement. • Unstamped reinforcing steel shop drawings and details of reinforcement placement, including bracing, centering and lifting methods and the method for supporting the reinforcement on the bottom of the shaft excavation. Include details on the type, number and placement of spacers and other devices for ensuring the reinforcing c age position is maintained during construction. • Evidence that the proposed M aterials conform to all applicable Specifications. • Details of concrete placement, including proposed operational procedures for pumping and tremie methods. • Detailed procedures for T emporary Casing installation and removal. Include casing diameters, dimensions, and depths and the methods and Equipment for casing installation and removal. • Confinement methods required to contain drilling fluids, spoils, waste concrete and other produc ts from contacting sensitive environmental areas according to Section 00290 and all applicable regulatory permits. • Methods for protecting existing Structures according to 00170.82.
00963.43 941 The Engineer will approve or reject the D rilled Shaft installation plan wi thin 21 Calendar Days after receipt of all submissions. Provide any additional information and submit a revised plan, if requested, for review and approval. All procedural approvals given by the Engineer will be subject to trial in the field and will not relieve the Contractor of the responsibility to satisfactorily complete the Work . Submit requests for modification of adopted procedures to the Engineer. Allow 21 Calendar Days for approval of modifications. Do not begin Drilled Shaft construction Work until all Drilled Shaft submittals have been approved.
plan to the Engineer for approval. Furnish all Materials and Work , including engi neering analysis and design, needed to correct unacceptable Drilled Shafts, at no additional cost to the Agency. Do not begin repair operations before remedial procedures or designs are approved. Any modifications to the dimensions or M aterials of the D rilled Shafts shown that are proposed in the repair plan will require stamped calculations and Working Drawings according to 00150.35.
00963.41Drilled Shaft Coordination Meeting - Hold a Drilled Shaft coordination meeting at
least 7 Calendar Days befor e beginning any shaft construction Work at the site to discuss construction procedures, schedules, staging, personnel, Equipment to be used, and other elements of the approved shaft installation plan as specified in 00963.40. Those attending the meeting i nclude:
• Representing the Contractor - The superintendent, on- site supervisors, and all supervisors in charge of excavating the shaft, placing the T emporary Casing, placing the steel reinforcing bars, and placing the concrete.
• Representing the Contracting Agency - The Project Engineer, key inspection personnel, and designers of record or their appointed representatives.
If the Contractor's key personnel change, or if the Contractor proposes a significant revision of the approved shaft installation plan, an additional meeting shall be held before any additional shaft construction operations are performed.
00963.42Construction Tolerances - Excavate Drilled Shafts as accurately as possible at the
locations shown. Determine the D rilled Shaft dimensions and alignment with approved methods.
Frequently check the plumbness alignment and dimensions of the shaft during construction. Correct all out -of-tolerance shaft excavations and completed shafts to the satisfaction of the Engineer. Correct out-of-tolerance Drilled Shafts at no additional cost to the Agency, and no extension of the Project completion date will be granted. Materials and Work necessary to complete corrections for out-of-tolerance Drilled Shafts resulting from the removal of unexpected Drilled Shaft obstructions will be paid for according to 00195.20.
00963.43Drilled Shaft Excavation - Perform Drilled Shaft excavation according to the following:
Provide and maintain stabilized Drilled Shaft sidewalls for the full depth of the excavation, using approved Materials, Equipment and methods. If caving or other unstable conditions occur during any co nstruction procedure, stop further construction, notify the Engineer, and stabilize the shaft excavation by approved methods and submit a revised installation plan which addresses the problem and prevents further instability. Do not continue with shaft construction until any damage which occurred has been repaired according to the Specifications and until receiving the Engineer's approval of the revised shaft installation plan.
If the Engineer has reason to believe that the D rilled Shaft excavation techni ques or workmanship have been deficient, so that the integrity of any excavation is in question, Work on that D rilled Shaft 00963.45 942 may be stopped. Do not resume Drilled Shaft excavation until the deficient excavation techniques or workmanship have been changed t o the Engineer's satisfaction.
Dispose of materials removed from the shaft excavations according to 00290.20.
Do not leave partially completed shaft excavations open overnight unless they are cased full depth or otherwise stabilized with approved methods . If approved by the Engineer, a partially excavated shaft may be left open overnight, provided that the excavation:
• Is stabilized at the bottom, sides and surface to prevent Soil caving or swelling or a reduction of Soil strength, and • Is covered at the surface to protect the public.
Extend the Drilled Shaft excavation if the Engineer determines that the subsurface materials encountered are not capable of providing the required bearing resistance or differ from those anticipated in the design of the D rilled Shafts.
and of sufficient quantities to meet the needs of the anticipated construction method.
according to 00512.43(d).
considered unexpected obstructions and shall be removed without additional compensation. Drilling tools lost during the course of removing unexpected Drilled Shaft obstructi ons will be paid according to 00195.20.
00963.45Reinforcing Steel - Furnish and place reinforcing steel as shown and according to the
following:
approved the final elevation of the bottom of the shaft.
In each shaft, place reinforcing steel extending from 3 inches above the bottom of the shaft excavation to the elevation shown. The reinfor cing cage may be supported on the bottom of the shaft excavation if approved. Support the reinforcing cage to prevent distortion or settlement during concrete placement. If concrete placement does not immediately follow cage placement, remove the reinfor cing cage from the excavation and rectify the integrity of the excavation prior to reinstallation of the cage.
manner that does not cause permanent racking or distortion. Show bracing and any extra reinforcing steel required for fabrication of the cage on the submitted shop drawings. Remove cross bracing during cage placement, unless otherwise approved.
bars or other approved devices around the reinforcing cage. Provide details of the proposed centering method on the shop drawings submitted according to 00963.40.
00963.49 943 00963.47 Concrete - Furnish and place concrete according to the following:
and with the approval of the Engineer. Immediately prior to concrete placement ensure the shaft clean out requirements are met according to 00963.43(f).
Place concrete according to 00540.48(a) and continuously until concrete at the top of the shaft is free of water, Soil , and debris, and uncontaminated concrete extends to the plan top-of -shaft elevation. Dispose of all conta minated concrete expelled from the top of the shaft in an approved manner. Remove waste concrete from the site. If a delay in concrete placement occur because of a delay in concrete delivery or other factors reduce the placement rate to maintain a flow of fresh concrete into the shaft excavation.
Allow a maximum of 60 minutes between concrete placements and use no concrete older than 90 minutes from batch time. U se procedures for concrete placement which ensure that the concrete within the shaft becomes a monolithic, homogeneous unit. Place concrete using hoses or pipes having watertight joints. For concrete placement by gravity tremie, use hose or pipe having an inside diameter not less than 8 inches. For placement by concrete pump, use hose with ins ide diameter not less than 4 inches. Provide an alternate delivery system that can be used in case of failure of the primary delivery system. Place concrete only against the bottom of the D rilled Shaft or into fresh concrete.
If caving occurs during con crete placement, the shaft may be rejected.
to 00512.47(c).
of 7 Days by covering with wet burlap overlain with plastic sheets or by keeping top of concrete under water. Keep the burlap wet during the concrete cure.
Prior to placing any fresh concrete on top of a completed shaft, clean the upper surface of the concrete by removing all scum, laitance, loose Gravel and sediment and chip off any high spots on the upper surface that would prevent the steel reinforcing bar cage from being properly placed in the position shown.
placement. Do not start Temporary Casing removal until the level of fresh concrete within the casing has reached a depth of 10 feet or the level necessary to adequately counteract the external hydrostatic pressure head. As the T emporary Casing is withdrawn, maintain a minimum 5 feet head of concrete above the bottom of the casing. A slight downward movement of the casing while exerting downward pressure, or hammering or vibrating the c asing will be allowed to facilitate extraction. Extract the casing so that concrete is cast directly against the surrounding in-situ material. Check the elevation of the top of the reinforcing cage before and after Temporary Casing extraction for conformance with the construction tolerance criteria of 00963.42. Casing that cannot be extracted during or immediately after the concrete placement operation may be cause for rejection of the shaft.
00963.48Drilled Shaft Testing and Acceptance - Acceptance of D rilled Shafts will be based on the
Engineer's review of the field inspection reports and visual observations during Drilled Shaft construction. The Engineer has final authority on the approval of D rilled Shafts.
00963.49Scheduling and Restrictions - Do not proceed with additional shafts until the first Drilled
Shaft has been approved. After the first D rilled Shaft on the Project has been accepted, make no 00963.80 944 significant change in construction methods, Equipment or Materials used in the construction of subsequent shafts, unless approved by the Engineer.
For 24 hours after completion of concrete placement in a newly -constructed shaft, including withdrawal of casing if applicable, do not, within 15 feet of the shaft:
• Excavate adjacent shafts • Construct footings • Apply Equipment wheel loads • Introduce vibrations with a velocity greater than 1/4 inch per second
Measurement
00963.80Measurement - The quantities of signal support D rilled Shafts will be measured on the
length basis , by the vertical excavated length from the bottom of the shaft to the ground surface. If directed to construct D rilled Shafts below the elevations shown, the D rilled Shaft will be measured from the revised bottom of shaft.
Payment
00963.90Payment - The accepted quantities of signal support Drilled Shafts will be paid for at the
Contract unit price, per unit of measurement, for the following items:
Pay Item Unit of Measurement
Payment will be payment in full for furnishing and placing all Materials, and for furnishing all Equipment , labor, and Incidentals necessary to complete the Work as specified.
No separate or additional payment will be made for:
• excavating the shafts and disposing of the excavated material • furnishing, placing, splicing and removing temporary shaft casing and forms • concrete and all reinforcement • anchor rods, anchor plates, nuts, and washers