00512.14 429 Section 00512 - Drilled Shafts
Description
00512.00Scope - This Work consists of excavating and constructing drilled, cast -in-place, reinforced
concrete shafts, accordi ng to the Specifications and the Plans .
00512.01Definitions :
Drilled Shafts - Reinforced concrete sections, cast -in-place against in situ Soil, Rock , or a casing.
Permanent Casing - Casing designed as part of the drilled shaft and intended to remain in place after concrete placement is completed.
Temporary Casing - Casing installed to facilitate drilled shaft construction only and removed during or after concrete placement.
00512.02Subsurface 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.
The geotechnical d ata shown in the Plans is a compilation of pertinent information including, but not limited to, the Soils and Geological Exploration Logs.
Materials
00512.10Materials - Furnish Materials meeting the following requirements:
modified in this Section. Water may be added to the concrete mix at the Project Site only if allowed by the approved mix design.
00512.13Steel Casing - Furnish casing meeting the requirements of ASTM A252 or ASTM A36
Furnish Permanent Casing meeting the requirements of ASTM A36 with the application of supplemental requirement S5. Test each heat of steel at 40 °F with a minimum absorbed energy requirement of 15 foot pounds. Do not use previously used casing for Permanent Casing. 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 watertight prior to placement in the drilled shaft excavation.
00512.14Drilling Slurry - Furnish drilling slurry meeting one of the following requirements:
00512.15 430 Property Test Requirement
Density Mud Density API * 13B -1, Section 1 64 - 75 lb./cu. ft. Viscosity Marsh Funnel and Cup API * 13B -1, Section 2.2 26 - 50 sec./qt. pH Glass Electrode, pH Meter, or pH Paper 8 - 11 Sand Content Sand API * 13B -1, Section 5 4.0 % max.
Maintain slurry temperature at 40 °F or more during testing.
* American Petroleum Institute
to the manufacturer's recommendations and the Contractor's quality control plan. The Sand content of synthetic slurry shall be less than 1.0 percent prior to final cleaning and i mmediately prior to concrete placement.
drilled shaft. Use of water slurry without full -length casing will only be allowed with the Engineer's approval. Use water slurry conforming to the following requirements:
Property Test Requirement (Maximum) Density Mud Weight (Density) API 13B -1, Section 1 70 lb./cu. ft. Sand Content Sand 1.0 % Do not use blended slurries.
00512.15Crosshole Sonic Log Access Tubes - Furnish steel crosshole sonic log (CSL) access
tubes meeting the following requirements:
• Steel access tubes shall be at least 1 1/2 inch inside diameter Schedule 40 pipe conforming to ASTM A53, Grade A or B, T ype E, F, or S. • Use access tubes having a round, regular inside diameter free of defects and obstructions, including all pipe joints, in order to permit the free, unobstructed passage of the source and receiver probes used for the testing. Ensure that acc ess tubes are watertight, free from corrosion with clean internal and external faces to ensure good bonding between the drilled shaft concrete and the access tubes. Fit the access tubes with watertight caps on the top and bottom. • Access tube acceptance wi ll be based on manufacturer's certification that the furnished Material meets the requirements of this Specification.
00512.18Crosshole Sonic Log Cement Grout - Furnish non-epoxy grout or tendon grout from the
QPL or furnis h a pumpable CSL cement grout consisting of neat cement and water that has a water -cement ratio between 0.38 and 0.45. The portland cement for the pumpable CSL cement grout shall meet the requirements of Section 02010.
00512.19Quality Control - Maintain and be responsible for quality control of the drilled shaft Work
throughout the construction operation. The Engineer will inspect all drilling operations and verify the suitability of all drilled shaft const ruction procedures. Provide lights, mirrors, weighted tape, weighted 00512.40 431 probe, personnel, and all assistance required for the Engineer to perform inspection during drilled shaft construction.
Labor
00512.30Personnel Qualifications - Perform the drilled shaft construction Work using a company
and personnel experienced in drilled 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 compan y's experience relevant to the Project. Experience shall be relevant to the anticipated subsurface materials, groundwater conditions, shaft size, depth and any special construction techniques required. Also provide the experience qualifications of the company performing the quality assurance testing. Before the preconstruction conference, provide the following information to verify the firm's experience and the qualifications of personnel scheduled to perform the drilled shaft construction and quality assu rance testing:
• 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. • On-site supervisors shall have at least 2 years ' experience in supervising construction of dr illed shaft foundations of similar size (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 drilled shaft foundations. • Perform quality assurance testing using an independent testing organization retained by the Contractor and approved by the Agency. Furnish personnel experienced in operating the specific quality assurance testing Equipment . Submit the CSL testing firm qualifications according to 00512.40(a). The quality assurance testing firm qualification shall have successfully perfor med quality assurance testing on a minimum of five projects during the last 3 years. Quality assurance testing personnel shall be trained in the operation of the quality assurance Equipment and have at least 1 year of experience in operating quality assurance testing Equipment on a minimum of 10 shafts. The Engineer will respond within 21 Calendar Days after receipt of the submittal. Do not begin Work on any drilled 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 supervi sors, drill operators, or CSL testing personnel 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 is the Contractor's responsibility, and no adjustment in Contract Time resulting from the suspension of Work will be allowed.
Construction
00512.40Submittals - Provide the following submittals to the Agency for review and approval:
construction, submit the following:
• The sequence of drilled shaft construction as it relates to the overall construction 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 00512.40 432 the successful use of the Equipment for Drilled Shafts of equal or greater size in similar subsur face 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. Include 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 drilled shaft stability during excavation and concrete placement. • Details for the use of drilling slurry including mix design, slurry head requirements, mixing methods, maintaining, and disposing of the slurry (if applicable). Include a discussion of the suitability of the proposed drilling slurry in relation to the anticipated subsurface conditions. • A plan for quality control of all drilling slurries, if their use is proposed. In the quality control plan, include property requirements, required tests and test methods to ensure the slurry performs as intended. Submit to the Engineer the name and current phone number of synthetic slurry manufacturer's representatives who wil l provide technical assistance during construction. Provide the names of the Contractor's personnel assigned to the Project and trained by the synthetic slurry manufacturer in the proper use of synthetics slurries. • Unstamped reinforcing steel shop drawings and details of reinforcement placement, including bracing, splicing, centering, and lifting methods and the method for supporting the reinforcement according to 00150.35. Include details on the type, number, and placement of spacers and other devices for ensuring the reinforcing cage position is maintained during construction. Include details for attaching the CSL test access tubes to the reinforcing cage (if applicable). • Evidence that the proposed Materials and concrete mix design conform to all applicable Specifications. • If the concrete mix design allows the addition of water at the Project Site, documentation that specifies the amount of water that may be added and allowable methods for adding the water. • Documentation that the workability and slump retention properties of Section 02001 are met. • Details of concrete placement, including proposed operational procedures for pumping and tremie methods. Include details for grout placement in the crosshole sonic logging test access tubes after testing is com pleted (if applicable). • Detailed procedures for Permanent Casing installation and Temporary Casing installation and removal. Include casing diameters, dimensions, and depths and the methods and Equipment for casing installation and removal. • Quality assurance testing company performing the quality assurance testing Work , including documentation demonstrating that the company, and company personnel, meets the required qualifications. • Confinement methods required to contain drilling fluids, spoils, wast e concrete and other products from contacting sensitive environmental areas according to Section 00290 and all applicable regulatory permits. • Methods for protecting existing Structures according to 00170.82. The Engineer will approve or reject the drilled shaft installation plan within 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 tria l 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 00512.42 433 21 Calendar Days for approval of modifications. Do not begin dril led shaft construction Work until all drilled shaft submittals have been approved.
plan to the Engineer for approval. Furnish all Materials and Work , including engineering 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 Material of the Drilled Shafts shown that are proposed in the repair plan will require stamped calculations and Working Drawings according to 00150.35.
Inspection Report for eac h drilled shaft, detailing the actual location, alignment, elevations, dimensions, and quantities of the shafts. Submit the report within 21 Calendar Days after the completion and acceptance of each shaft. A "Drilled Shaft Inspection Report" form is avai lable from the Engineer.
into Drilled Shafts using standard ODOT forms designated for this purpose or other forms approved by the Engineer. Provide the Engineer with a completed Drilled Shaft Concrete Placement Log and Concrete Volume Curve Form for each drilled shaft within 24 hours after completion of shaft concrete placement.
00512.41Drilled Shaft Coordination Meeting - Hold a drilled shaft coordination meeting at
least 7 Calendar Days before 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 00512.40. If synthetic slurry is used to construct the shafts, the frequency of scheduled site visits to the Project Site by the synthetic slurry manufacturer's representative will be discussed. Those attending the meeting include:
• Representing the Contractor - The superintendent, on- site supervisors, and all supervisors in charge of excavating the shaft, placing the casing, mixing and installing slurry (as applicable), placing the steel reinforcing bars, and placing the concrete. I f synthetic slurry is used to construct the shafts, the slurry manufacturer's representative and a Contractor's employee trained in the use of the synthetic slurry shall also attend.
• Representing the Contracting Agency - The Project Engineer, key inspecti on 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, hold an additional meeting before any additional shaft construction operations are performed.
00512.42Construction Tolerances - Excavate Drilled Shafts as accurately as possible at the
locations shown and within the specified tolerances listed below. Determine t he Drilled Shaft dimensions and alignment with approved methods. The following construction tolerances apply to Drilled Shafts unless otherwise stated:
• Horizontal Position ( at the Plan Elevation of the Top of Shaft):
• Shaft Diameter Less Than or Equal to 6 Feet - 3 inch horizontal tolerance from the location shown. • Shaft Diameter Greater Than 6 Feet - 6 inch horizontal tolerance from the location shown.
00512.43 434 • Top Elevation of Shaft Concrete:
• Top Elevation above Water - Minus 3 inches to plus 1 inch from the plan top of shaft elevation.
• Top Elevation u nder Water - Minus 3 inches to plus 6 inches from the plan top of shaft elevation.
• Vertical Alignment in Soil - May not vary from the plan alignment by more than 1.5 percent of the shaft length.
• Vertical Alignment in Rock - May not vary from the plan alignment by more than 2 percent of the shaft length.
• Top of Steel Reinforcement - Plus or minus 6 inches from the plan top of steel reinforcement elevation.
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. Materials and Work necessary to complete corrections for out -of-tolerance Drilled Shafts will be 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.
00512.43Drilled Shaft Excavation - Perform drilled shaft excavation according to the following:
Provide and maintain stabilized drilled shaft sidewalls and bottoms for the full depth of the excavation, using approved M aterials, Equipment and methods. If caving or other unstable conditions occur during any construction 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 drilled shaft excavation techniques or workmanship have been deficient, so that the integrity of any excavation is in question, Work on that drilled shaft may be stopped. Do not resume drilled shaft excavation until the deficient excavation techniques or workmanship have been changed to 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. • 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.
to existing Structures and utilities. Preventive measures include, but are not limited to, selecting 00512.43 435 construction methods and procedures that will prevent caving of the shaft ex cavation and monitoring and controlling the vibrations from construction activities such as the driving and vibrating of casing or sheeting, drilling of the shaft, or from blasting, if blasting is allowed. Repair all damage caused to existing Structures, utilities or other facilities, resulting from drilled shaft construction activities, at no additional cost to the Agency.
and of sufficient quantities to meet the needs of the anticipated construction method.
Where the peak horizontal ground acceleration coefficient for the 1,000- year return period used for seismic design of the Structure is less than or equal to 0.16 g (acceleration due to gravity), temporary tel escoping casing may be used for the Drilled Shafts, subject to the following conditions:
• Submit the request to use temporary telescoping casing to the Engineer for approval. Specify the diameters and lengths of the temporary telescoping casing and the shafts where use is requested. • The minimum diameter of the shaft shall be as shown. • Backfill all voids between the temporary telescoping casing and the plan shaft dimensions with a M aterial that approximates the geotechnical properties of the subsurface Soils, or with concrete as approved. • Use temporary telescoping casing material conforming to 00512.13.
encountered that was not revealed by the Agency's site investigation, and that would cause a significant decrease in the rate of advancement if removed using the techniques and Equipment used successfully to excavate the shaft. The Engineer will be the sole judge of the significance of any reduced rate of shaft advancement and the classification of any unexpected obstructions. Removal of unexpected obstructions from the shaft excavation will be paid according to 00195.20.
considered unexpected obstructions and shall be removed without additional compensation. Drilling tools lost during the course of removing unexpected drilled shaft obstructions will be paid according to 00195.20.
representative to provide technical assistance at the site prior to use of the slurry, who shall remain at the site during construction and completion of a minimum of one drilled shaft to adjust the slurry mix for the specific site subsurface conditions. After the manufacturer's representative is no longer at the site, provide the approved personnel trained in the use of the synthetic slurry for the remainder of the shaft slurry operations to supervise the proper slurry mix design and quality control procedures.
All in -hole drilling slurry shall meet the required slurry specifications during excavation and prior to concrete placement. Clean, recirculate, de-sand or replace the slurry to maintain the required slurry properties.
Unless otherwise approved, maintain the level of slurry in the excavation at not less than 5 feet above the groundwater level for mineral slurries or 10 feet above the groundwater level for synthetic or water slurries. Maintain the slurry level a sufficient distance above all unstable zones to prevent bottom heave, caving or sloughing.
Maintain the required slurry properties and levels at all times during shaft construction, including Work stoppages, unless other approved stabilization methods are applied.
00512.45 436 Feed slurry continuously into the shaft excavation as drilling progresses so that a stable excavation is maintained. Use a self -priming pump to reclaim the slurry. Keep a standby pump available during the drilling operation.
appropriate storage facility. C ollect sample sets from the storage facility and perform tests to ensure the slurry conforms to the specified Material properties before introduction into the drilled shaft excavation. A sample set shall be composed of samples taken at mid-depth and withi n 24 inches of the bottom of the storage facility.
Sample and test all slurry in the presence of the Engineer, unless otherwise directed. The sample sets of slurry within the excavation shall consist of samples taken at mid-depth of the excavation and wi thin 24 inches of the bottom of the excavation. Collect and test sample sets during the drilling operation as necessary to ensure the specified properties of the slurry are maintained. Clean, recirculate, de-sand, or replace the slurry as necessary to maintain the specified slurry properties. Final cleaning of the excavation and placement of concrete is not allowed until the test results indicate the slurry properties are as specified.
Perform a minimum of two sets of slurry tests per 8 hour work shift, the first test being done at the beginning of the shift. Field conditions may require more frequent testing to ensure acceptable slurry properties. Make copies of all slurry test results available to the Engineer on request.
bottom of the drilled shaft excavations. No more than 2 inches of loose or disturbed material will be allowed at the bottom of the excavation for end-bearing Drilled Shafts. No more t han 6 inches of loose or disturbed material will be allowed at the bottom of the excavation for side friction D rilled Shafts. Assume end-bearing shafts unless otherwise shown or specified. Shaft cleanliness will be determined by the Engineer.
Notify the Engineer of completion of each drilled shaft excavation to permit inspection before proceeding with construction. Measure final shaft depths with a suitable weighted tape or other approved method after final cleaning to determine that the shaft bottom me ets the requirements in the Contract. Do not proceed with shaft construction until the bottom cleanliness requirements have been met and the bottom (shaft tip) elevation is approved.
00512.45Reinforcing Steel - Furnish and place reinforcing steel as s hown and according to the
following:
approved the final elevation of the bottom of the shaft.
In each shaft, place reinforcing steel extending from 6 inches above the bottom of the shaft excavation to the elevation shown. Support the reinforcing cage to prevent distortion or settlement during concrete placement. If concrete placement does not immediately follow cage placement, remove the reinforcing 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 distorti on. 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.
00512.47 437 (c) Splicing - Splice all drilled shaft reinforcement using appr oved mechanical splicer's unless otherwise shown or approved.
bars or other approved devices around the reinforcing cage. Place spacing devices on maximum 10 foot vertical spacing the full length of the shaft. At each 10 foot level, place spacers on a maximum 30 inch circumferential spacing with at least three spaces per level. Do not use wood spacers or concrete dobies. Provide details of the proposed centeri ng method on the shop drawings submitted according to 00512.40.
00512.46Crosshole Sonic Log Test Access Tubes - Furnish and install access tubes for CSL
testing as shown. Attach CSL access tubes securely to the interior of the reinforcement cage as near to parallel as possible in each drilled shaft and in the pattern shown. Extend the access tubes from the bottom of the reinforcement cage to at least 24 inches above the top of the shaft. Joints required to achieve full -length access tubes shall be watertight. Do not damage the access tubes during reinforcement cage installation and concrete placement. Fill the tubes with potable water, according to 02020.10(b), as soon as possible, but no more than 1 hour after concrete placement and reinstall the top watertight caps. Check water level and top off as needed.
Replace all access tubes that the test probe cannot pass through to the full depth of the shaft at no additional cost to the Agency. Replace all damaged access tubes wit h 1.5 inch to 2.0 inch diameter holes cored through the concrete for the entire length of the shaft. Unless otherwise directed, locate replacement core holes approximately 6 inches inside the reinforcement. Do not damage the shaft reinforcement during coring operations. Fill the access tubes with grout only after all CSL testing has been completed and the shaft has been accepted.
00512.47Concrete - Furnish and place concrete according to the following:
and with the approval of the Engineer. Prior to concrete placement, ensure the shaft clean-out requirements are met according to 00512.43(h) and the properties of the slurry (if used) conform to the Specifications . Shaft concrete may be placed without mechanical vibration in those areas of the drilled shaft that are not formed or are below the ground line or the water surface.
Place concrete continuously until concrete at the top of the shaft or at the top of the first construction joint, is free of water, Soil, and debris, and uncontaminated concrete extends to the plan top- of-shaft elevation or to the top of the construction joint, as applicable. For shafts with a non- contact splice, clean and roughen the s urface of the shaft construction joint according to the applicable portions of 00540.43(a). Dispose of all contaminated concrete expelled from the top of the shaft in an approved manner. Remove waste concrete from the site. If a delay in concrete placem ent occurs 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. Use 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 of at least 8 inches. For placement by concrete pump, use hose with inside diameter of at least 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 drilled shaft or into fresh concrete.
00512.47 438 If caving occurs during concrete placement, the shaft may be rejected.
conditions are met:
• No more than 3 inches of water is present in the bottom of the excavation at the beginning of the pour. • Groundwater seepage into the excavation is at a rate of no more than 12 inches per hour. • Shaft diameter is greater than or equal to 3 feet.
Under free-fall placement, deposit concrete through the center of the reinforcement cage by a method which prevents segregation of Aggregates and splashing of concrete on the reinforcement cage. Place concrete so that the free-fall is vertical down the center of the shaft without hitting the sides, the steel reinforcing bars or steel cage bracing.
requirements for dry concrete placement, stabilize water inflow and place the concrete under water or slurry with a tremie pipe or pump hose according to 00540.48(e). Place concrete continuously from the bottom of the shaft to the top- of-shaft elevation shown. Use a plug in the tremie pipe or pump hose to force water or slurry ahead of the advancing flow of fresh concrete. Dispose of all displaced water, slurry, or waste concrete according to 00290.20. When groundwater, the drilling water or slurry in the shaft excavation is to be removed by pumping during concrete placement, have a standby pump available. Place concrete in a continuous operation so that the concrete always flows upward within the shaft. Withdraw the delivery hose or pipe slowly as the elevation of the fresh concrete rises in the shaft. Keep the discharge end of the pipe or hose at least 5 feet below the surface of the concrete after the concrete has reached a depth of 5 feet. Maintain sufficient concrete inside the hose or pipe to prevent drilling fluid from entering. During concrete placement, provide and maintain markings on the tremie pipe or pump hose, or a sounding device or other appropriate method to determine the relative elevations of the fresh concrete surface and the bottom end of the pipe or hose. Raise the bottom end of the pipe or hose only when the pipe or hose has a sufficient head of fresh concrete to prevent the formation of a void at the bottom.
of 7 Calendar 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 sur face 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. Remove all loose material and poor quality concrete at the top of the shaft down to sound concrete prior to performing any required CSL testing.
placement. Do not start Temporary Casing removal until the level of fresh concrete within the casing has reached a depth of at least 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 casing will be allowed to facilitate extraction. Extract the casing so that concrete is cast directly agains t 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 00512.42. Casing that cannot 00512.48 439 be extracted during, or immediately after, the concrete placement operation may be cause for rejection of the shaft.
Remove the tops of Permanent Casing to the top of the drilled shaft or the finished groundline, whichever is lower, unless otherwise shown or directed. Remove the tops of Permanent Casing for shafts constructed in a permanent body of water to the low water elevation, unless otherwise shown or directed.
00512.48Drilled Shaft Testing and Acceptance - Acceptance of D rilled Shafts will be based on the
Engineer's review of the results of CSL, or other, integrity testing (if conducted), field inspection reports and visual observations during drilled shaft construction. The Engineer has final authority on the approval of D rilled Shafts. For shafts that are integrity tested, t he Engineer will determine final acceptance of each tested shaft, based on the integrity test results and inspection reports and will provide a response to the Contractor within 5 Calendar Days after receiving the CSL test report.
crosshole sonic log testing and analysis on the first drilled shaft completed at each Structure and subsequent shafts as specified or designated for testing by the Engineer. Provide CSL testing Equipment conforming to the requirements of ASTM D6760 and approved by the Engineer. Provide all necessary access and other support to the CSL testing firm necessary to do the CSL testing Work .
Perform one C SL test on each shaft designated for testing. A single CSL test consists of all ultrasonic profile combinations in a given shaft. Test completed drilled shaft foundations using Ultrasonic Crosshole Testing methods (CSL Testing) according to ASTM D6760. I nform the Engineer of scheduled CSL testing at least 3 Calendar Days prior to the testing. Perform all CSL testing using the Contractor's CSL technician in the presence of the Engineer. Allow at least 3 Calendar Days of curing time before testing unless otherwise approved. Additional curing time beyond 3 Calendar Days may be required if the shaft concrete contains admixtures such as set retarding admixture or water reducing admixture. Additional CSL testing required due to the CSL testing being conducte d on concrete that has not cured sufficiently is at no additional cost to the Agency. Additional curing time required due to concrete admixtures will not be grounds for additional compensation or time extensions. For Drilled Shafts constructed using non-contact splice methods, perform CSL testing after the initial pour to the bottom of the splice region and before placement of the column reinforcement and pouring of the splice region.
data, with interpretation of the test results, to the Engineer at the completion of each test. Provide copies of the raw test data as requested. Mark the test data files to identify, as a minimum, the Structure , bent and shaft number, the date of CSL testing, depths of testing and any other pertinent information. Submit a stamped final CSL Test Report for each shaft tested according to 00150.35 and ASTM D6760. Provide electronic file copies of the raw CSL data measurements, if requested. The report shall summarize the CSL testing performed, data analysis, and interpretation of CSL data with special attention made to the identification and location of any anomalies or possible defects. Provide interpretation of the CSL test data in terms of overall shaft integrity and acceptance. Submit all reports to the Engineer within 5 Calendar Days of the performance of the tests.
to identify the location, extent and condition of possible shaft defects if requested by the Engineer. 00512.49 440 Additional testing and investigation may include, but is not limited to, additional CSL testing, excavation Work or core drilling.
If requested b y the Engineer, drill a core hole in any questionable quality shaft to explore the shaft condition. The number, location and depths of the core holes will be determined by the Engineer. Submit the method and Equipment used to drill and remove cores from the shaft to the Engineer for review and approval prior to drilling. Use a coring method that provides complete core recovery and minimizes abrasion and erosion of the core. If a defect is confirmed, as determined by the Engineer, all investigation costs associated with identifying the defect will be at no additional cost to the Agency and no extension of the Project completion date will be granted, regardless of whether the identified defect is repaired or not. If no defect is identified in the investigation Work , and the CSL tubes were satisfactorily installed according to ASTM D6760 and accepted, the Agency will pay for all coring and excavation costs associated with the additional investigation and grant an appropriate time extension, if required, according to Section 00190 and Section 00195. If it is determined by the Engineer that the CSL tubes were not installed properly thus invalidating the CSL test results, all coring, excavation, and other investigation and evaluation costs will be at no additi onal cost to the Agency and no extension of the Project completion date will be granted. Fill all core holes with grout only after the evaluation process is completed and the shaft is accepted and approved.
Perform additional CSL testing, or other investigation required, as directed by the Engineer, to confirm the quality of the completed shaft repair Work at no additional cost to the Agency with no time extension granted.
For Temporary Casing not extracted from the shaft excavation, submit a repair plan or a structural evaluation to the Engineer for approval according to 00512.40. If caving occurs during concrete placement submit a repair plan to the Engineer f or approval.
00512.49Scheduling and Restrictions - Unless otherwise approved, do not proceed with
construction of subsequent shafts until the CSL testing has been completed on the first drilled shaft and the results have been approved and accepted, in writing by the Engineer. Approval to proceed with the construction of subsequent shafts, before receiving approval of the first shaft will be based on the Engineer's observations of the Contractor's workmanship during construction of the first shaft and t he Engineer's review and assessment of the following:
The Contractor's conformance with the approved shaft installation plan. The Contractor's daily reports and Inspector 's daily logs of excavation, rebar, and concrete placement. The concrete placement logs and volume curves.
Written notification will be provided to the Contractor on whether or not to proceed with subsequent shaft construction within 24 hours after completion of the first shaft. If the Engineer determines the first shaft to be of questio nable quality, discontinue all shaft construction until the CSL test results of the first shaft are received and reviewed and the shaft accepted, in writing, by the Engineer.
Denial of permission to proceed with subsequent shaft construction will not be c ause for C ontract Time extension.
00512.90 441 Do not proceed with the third drilled shaft until the final CSL test results from the first drilled shaft has been received and reviewed and the shaft accepted, in writing, by the Engineer. Allow 5 Calendar Days for the Engineer to review. After the first drilled shaft on the Project has been accepted, make no significant changes in construction methods, Equipment, or M aterials used to construct subsequent shafts, unless otherwise approved.
Measurement
00512.80Measurement - The quantities of Work performed under this Section will be measured
according to the following:
Equipment .
the vertical excavated length from the bottom of the shaft to the ground surface or to the mudline if under water. If the top of the shaft is located below the original ground surface, measurement will be made to the top of the shaft as shown or directed. If directed to excavate D rilled Shafts below the elevations shown, the drilled shaft excavation will be measured from the revised bottom of shaft.
Estimated quantities of concrete will be listed in the Special Provisions.
reinforcement. Estimated quantities of reinforcement will be listed in the Special Provisions.
basis of the number of tubes installed in the shafts.
Grout used to fill the access tubes after the completion of CSL testing will not be measured.
completed, repor ted, and accepted. No measurement will be made for CSL Equipment and operating personnel or for CSL tests performed at the Contractor's option.
Payment
00512.90Payment - The accepted quantities of Work performed under this Section will be paid for
at the Contract unit price, per unit of measurement, for the following items:
Pay Item Unit of Measurement
00512.90 442 Item (a) includes furnishing and moving the drilling Equipment to the Project, setting up the Equipment at the various locations on the Project and removing the Equipment from the Project.
Partial payments for item (a) will be made as follows:
• When drilling Equipment is on the job, assembled and ready to excavate the shafts ........... 60% • When all shafts have been excavated and shaft concrete has been placed and accepted .. 40%
In item (b), the diameter of the shaft casing will be inserted in the blank. In item (c), the diameter of the shaft will be inserted in the blank. Item (c) includes excavating the shafts and disposing of the excavated material and for furnishing, placing, splicing, and removing temporary shaft casing and forms.
In item (e), the grade of reinforcement will be inserted in the blank.
Item (e) includes all reinforcement within the drilled shaft plus the reinforcement shown which is to be embedded in the shaft and extends above the top of the drilled shaft including the continuous vertical and spiral reinforcement extending from the bottom of the shaft to the elevation shown. No separate or additional payment will be made for bracing, mechanical splices, centering devices, or support for the bottom of the reinforcement cage.
Item (f) includes filling the tubes with grout after completion of CSL testing.
Item (g) includes mobilization of all CSL testing Equipment and personnel to and from the site, all CSL testing, interpretation, analysis, electronic data, and final report for each tested and accepted shaft. 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.
If the Contractor chooses to use a larger shaft diameter casing than the shaft diameter shown, no additional payment will be made for the larger casing, or for the additional excavation, concrete, and reinforcement.