465 Page 341465 DRILLED SHAFT CONSTRUCTION
465.1DESCRIPTION
This work consists of all labor, materials, equipment, and services required in the construction of drilled shafts.
465.2MATERIALS
A.Concrete: Drilled shaft concrete will conform to the requirements of Section 460, except as modified by this Section. B.Controlled Density Fill: Section 464. C.Casing: Casing will be smooth steel of sufficient thickness to withstand handling stresses, concrete pressure, surrounding earth and fluid pressures, and live load surcharges (if applicable). The casing will be of the diameter specified and will have teeth at the bottom to facilitate proper seating of the casing into the plans specified formation. D.Access Tubes for Crosshole Sonic Log (CSL) Testing: Access tubes will be 1.5 to 2 inch I.D. steel pipe conforming to ASTM A53. The selected pipes must have a round diameter free of defects or obstructions, including any at the pipe joints, to permit a free, unobstructed passage of the source and receiver probes. The pipes must be watertight and free from corrosion with clean internal and external faces to ensure smooth passage of the probes and to secure a good bond between the concrete and tubes. The pipes will each be fitted with a watertight shoe on the bottom, which can be penetrated from the surface to allow tip grouting, and a removable cap on the top. E.Grout: Grout for filling the access tubes at the completion of the CSL tests will conform to the requirements of Section 460.2 or will consist of Portland cement, water, and a water reducing admixture mixed in the following proportions: Portland Cement Type I or II........................ 1 Sack (94 lbs.) Water ............................................................ 4.5 Gallons Maximum Water Reducing Admixture .......................... Manufacturer’s Recommendation Fly Ash (Optional) ........................................ 20 Pounds Maximum
465.3CONSTRUCTION REQUIREMENTS
A.Concrete Quality and Proportioning: The Contractor will design and be responsible for the performance of the concrete mix. The concrete mix will have the following characteristics: 1.Minimum cementitious content of 750 pounds per cubic yard. The maximum cementitious content (total cement, fly ash, and other cementitious admixture) content will be 800 pounds per cubic yard. The Contractor will substitute a portion of the cement with Class F modified fly ash in accordance with Section 605. The amount of cement to be replaced will be 20% to 25% by weight. The ratio of substitution of fly ash to cement will be 1:1 by weight; 465 Page 3422.Coarse aggregate will conform to Section 820 and be either size #1, #1A, or #15; 3.Minimum 28 day compressive strength of 4500 psi; 4.Slump at time of placement will be between 6 and 8 inches for concrete that is placed by the free-fall or tremie method. The slump at the time of placement will be between 7 and 9 inches for concrete that is pumped through a tremie. In addition, the slump will be maintained above 4 inches for 4 hours from the time of batching regardless of the placement method. Slump loss will be tested in accordance with SD 423. Slump loss will be tested within 30 days prior to placing concrete in each shaft. 5.Initial set of the concrete obtained within 12 hours of completion of placing concrete for each drilled shaft; 6.Entrained air content of 6.5% with an allowable tolerance of +1% to -1.5%. 7.The mix design will establish a maximum water cementitious material ratio for the concrete mix (never to exceed 0.44). The use of a water reducer will be required to achieve the above properties. Water reducers conforming to AASHTO M 194 Type C (Accelerating) and Type E (Water-Reducing and Accelerating) will not be permitted. B.Drilled Shaft Installation Plan: Not less than 30 calendar days before beginning drilled shaft construction, the Contractor will submit an installation plan to the Department for the Department’s opportunity for review. Any review by the Department of the installation plan is limited to general conformance with the contract plans and specifications only. The Contractor will send an email with the installation plan attached as a PDF to the Project Engineer and Office of Bridge Design. Upon request, the Project Engineer will provide the Contractor the appropriate email addresses. Within 14 calendar days of receiving the installation plan, the Office of Bridge Design will respond to the Contractor in one of the following ways: 1) No Exceptions Noted or 2) Returned for Revision. If the Department’s response states, “Returned for Revision”, the Contractor must make the revisions and resubmit the installation plan for review as specified above. The Contractor will not begin drilled shaft construction until the Department has confirmed, in writing, a completed review with a response of “No Exceptions Noted”. The installation plan will provide the following information: 1.A list of all proposed equipment to be used and available on site including, but not limited to, cranes, casing, drill augers, pilot bits, bailing buckets, final cleaning equipment, air lifts, water trucks, dewatering pumps, tremies, concrete pump line, etc. Include the casing diameter and wall thickness in the equipment list; 2.Details of the overall shaft construction sequence in each substructure unit or group of drilled shafts; 3.A detailed explanation of how the casing is to be installed. It is required that a T-bar be on the project site such that the casing can be twisted into the specified formation to achieve as watertight of a seal as possible. Tamping or pounding the casing into the ground will not be allowed; 465 Page 3434.Details of shaft excavation methods to be used; 5.Methods to be used to clean the shaft excavation; 6.Details of reinforcement centering devices and their spacing; 7.Details and methods for supporting and lifting reinforcing steel cages; 8.Details of the concrete pump line and tremie tube that is to be used in the event that a wet excavation is encountered. Include all other details of concrete placement such as free fall (allowed only for shafts 36 inches in diameter or greater), pumping, etc. A tremie tube is required to be on the project site. The tremie tube must be long enough to extend from the bottom of the hole to the top of the reinforcing cage. Details for the disposal of contaminated concrete from a wet excavation will also be included; 9.The Contractor will verify all existing ground and water elevations and establish the elevations of any work platforms, etc. that may be used. These elevations will be included in the drilled shaft installation; and, 10.CSL Testing Organization and Personnel: The Contractor will submit the name of the independent testing organization and the names of the personnel conducting the CSL tests. The submittal will include documentation that the qualifications specified below are satisfied. The independent testing organization and the testing personnel will meet the following minimum qualifications: a.The testing organization will have performed CSL tests on a minimum of three deep foundation projects in the last two years. b.Personnel conducting the tests for the testing organization will have a minimum of one year experience in CSL testing and interpretation. C.General Requirements: A drilled shaft preconstruction meeting is required to be held a minimum of 5 working days prior to beginning drilled shaft construction. A representative from the bridge Contractor, drilled shaft subcontractor, concrete supplier, Area Office, and Office of Bridge Design is required to attend this meeting. The drilled shaft installation plan will be discussed at the meeting and the responsibilities of each of the parties involved clearly identified. The Contractor will perform the excavation for the shafts through the various types of materials that are encountered. The excavation will be to the dimensions and elevations shown in the plans, final diameter and depth, and filled with concrete within 24 hours of encountering frictional bedrock. In the event the 24 hour timeframe will be exceeded, drilled shaft operations will cease and the office of Bridge Design will be immediately notified. To preserve the design capacity of the bedrock, the Contractor may be required to fill the excavation with controlled density fill at no additional cost to the Department. Contractor methods and equipment will be suitable for the intended purpose and materials encountered. All the equipment listed in the drilled shaft installation plan will be on the project site fully assembled and inspected by DOT staff prior to the start of work. The following 465 Page 344equipment is required to always be available for use on the project site during drilled shaft construction: 1.Tremie and concrete pump line (if used) of sufficient length to reach the bottom of the drilled shaft and clear the top of the reinforcing cage; 2.T-bar for installing casing; 3.Flat bottom cleanout bucket of the proper size; 4.Graduated measuring device to determine excavation and water depth; 5.Pilot bit capable of drilling through rock; and, 6.A pump of sufficient capacity to remove the displaced water during underwater placement of concrete and for filling the excavation with water when required due to caving in or water bearing soils. Dewatering is a requirement prior to concrete placement by the free fall method; and, 7.Water tank(s), water truck(s), or on site water source of at least 2 times the volume of the drilled shaft. Unless otherwise specified on the plans, the Contractor will begin drilled shaft excavation using the dry construction method. The Contractor will use the temporary casing construction method when specified on the plans or when caving soils or ground water is encountered during excavation that is begun by the dry construction method. The permanent casing construction method will be used only when specified on the plans or approved by the Office of Bridge Design. Upon completion of the excavation of a drilled shaft, a flat bottom cleanout bucket and no less than 12 inches smaller than the final diameter of the shaft will be used to remove all loose material from the bottom of the shaft. Wet shaft excavations will be cleaned using an air lift system. After cleanout, the reinforcing steel will immediately be installed and the concrete placed prior to start of excavation for another drilled shaft. The Department will only allow the Contractor to construct one drilled shaft per day. For drilled shaft concrete pours of 18 cubic yards and less, the Contractor will have all of the concrete necessary to complete the drilled shaft at the project site and tested prior to placing any concrete in the drilled shaft. Vibrations caused by any work activities that may be detrimental to the freshly placed concrete will not be allowed for at least 72 hours after placement or until the concrete has attained a minimum compressive strength of 1600 psi. If the Engineer suspects that construction activities may be causing excessive vibration, a 2 x 4 inch stake will be driven solidly into the ground adjacent to the freshly placed concrete. A small container of water will then be placed on top of the stake. If the water surface remains calm, the construction activity will be allowed to continue. When the water surface shows any movement, vibrations are reaching the freshly placed concrete, and the construction activities will be either stopped or altered such that vibrations at the freshly placed concrete are eliminated. 465 Page 345D.Dry Construction Method: The dry construction method consists of drilling the shaft, removing loose material from the excavation and placing the concrete in a relatively dry excavation. The Engineer must be able to inspect the sides and bottom of the excavation before placing the reinforcing steel cage and concrete. The dry construction method will be approved by the Engineer when the shaft excavation has: a water accumulation rate of 3 inches or less per hour; the sides and bottom of the excavation remain stable without detrimental caving, sloughing or swelling; and loose material and water can be removed before inspection and concrete placement. E.Temporary Casing Construction Method: The temporary casing construction method will be used when excavations, begun by the dry construction method, encounter water bearing or caving soil formations, or when specified on the plans. If, during dry drilling, the Contractor encounters caving or water bearing soils, the Contractor will stop drilling and fill the hole with water to a point above the ground water elevation. If practical, a positive 10 foot head of water will be maintained above the ground water elevation. When necessary, a temporary casing may be required to achieve this head. If caving soil is encountered, a sufficient head of water will be maintained to stop the caving. Once the hole is filled with water, the excavation will be advanced by drilling to a depth at which an impervious formation is reached. A sufficient head of water will be maintained during the drilling operation. A temporary casing will then be placed into the impervious formation by use of a T-bar and twisting the casing into the specified formation to produce a watertight seal at the bottom. Other methods of seating the casing may be used with the Engineer's approval. The casing and the seal at the bottom of the casing will be watertight. Water will be pumped out of the temporary casing and the excavation continued using the dry construction method. During concrete placement, the casing will be withdrawn. If a watertight seal cannot be achieved at the bottom of the casing, the shaft will be drilled to the final elevation while keeping the hole full of water to maintain an adequate fluid head to control caving. Concrete will then be placed using proper underwater concrete placement methods. 1.If the Contractor elects to remove a casing and substitute a longer casing through caving soils, the excavation will be backfilled before a new casing is installed. Other methods may be used to control the stability of the excavation and protect the integrity of the foundation soils when approved by the Engineer. 2.Temporary casing will be removed before any of the drilled shaft concrete attains initial set. Before the casing is withdrawn, the level of fresh concrete in the casing will have sufficient head so all water trapped behind the casing is displaced upward without contaminating or displacing the concrete. When water seepage cannot be stopped and water is required to maintain stability of the perimeter of the hole, the concrete will be placed in the shaft using a tremie or pump. Simultaneously extract the casing and tremie, or pump, at a slow uniform rate. Maintain a sufficient head of concrete above the bottom of the casing to overcome the hydrostatic pressure outside the casing. The bottom of the tremie, or pump, will always be embedded a minimum of 5 feet into the fresh concrete during the extraction. 3.Temporary casing will be removed at the time of concrete placement. When a casing becomes bound in the excavation, drilled shaft construction will cease and the Engineer will immediately inform the Office of Bridge Design. 465 Page 346F.Permanent Casing Construction Method: The permanent casing construction method will be used only when specified on the plans or approved by the Office of Bridge Design. This method consists of placing a casing to a prescribed depth before excavation begins. If full penetration cannot be attained, the Engineer may require excavation of material within the embedded portion of the casing or excavation of a pilot hole ahead of the casing or both until the casing reaches the desired penetration. Over reaming to the outside diameter of the casing may be required before placing the casing, as approved by the Engineer. A T-bar will be used to twist the permanent casing into the specified formation to achieve a watertight seal at the bottom. Other methods of seating the permanent casing may be used with the Engineer's approval. The casing and the seal at the bottom of the casing will be watertight. If the Contractor elects to remove a casing and substitute a longer casing through caving soils, the Engineer may require that the excavation be backfilled before a new casing is installed. Other methods may be used to control the stability of the excavation and protect the integrity of the foundation soils when approved by the Engineer. If, during dry drilling, the Contractor encounters caving or water bearing soils, the Contractor will stop drilling and fill the hole with water to a point above the ground water elevation. If practical, a positive 10 foot head of water will be maintained above the ground water elevation. If caving soil is encountered, a sufficient head of water will be maintained to stop the caving. Once the hole is filled with water, the excavation will be advanced by drilling. A sufficient head of water will be maintained during the drilling operation. Upon completion of drilling and cleaning, the Contractor will cut off the permanent casing to the plan shown cutoff elevation. When the cutoff elevation is not shown on the plans, the cutoff elevation is assumed to be 1 foot above flowline or ground line as appropriate. G.Excavation and Drilling Equipment: Excavation and drilling equipment will have adequate capacity including power, torque, and downward force. The excavation and over reaming tools will be of adequate design, size, and strength to perform the work shown in the plans and described in this specification. The excavation and drilling equipment will be capable of excavating to the plans depth without the use of an extension bar. When the material encountered cannot be drilled using conventional earth augers and under reaming tools, the Contractor will provide special drilling equipment including, but not limited to, rock core barrels, rock tools, air tools, blasting materials, and other equipment as necessary to excavate the shaft to the size and depth required. Approval by the Engineer is required before any excavation by blasting is conducted. H.Reinforcing Steel Cage Construction and Placement: The reinforcing steel cage (consisting of longitudinal bars, spirals or tie bars, cage stiffener bars, spacers, crosshole sonic log (CSL) access tubes, and centralizers) will be completely assembled and placed as a unit into the excavated shaft. Placement of the reinforcing steel cage will take place immediately after the shaft excavation is inspected and approved by the Engineer and before concrete placement. The reinforcing steel cage will be tied and supported in the shaft so the cage will remain within the specified tolerances. Hanging the steel cage from the casing will not be allowed. 465 Page 347Welding of the reinforcing steel cage will not be allowed. Concrete centralizers or other approved noncorrosive centering devices will be used within 1 foot of the bottom. Centralizers will also be used at intervals not exceeding 5 feet along the length of the shaft. Each level of centralizers will be rotated 45 degrees in the horizontal plane relative to the level below. Concrete centralizers will be constructed of concrete equal in quality and durability to the concrete specified for the shaft. The concrete centralizers will have the ends beveled to minimize the potential for catching on obstructions during reinforcing steel placement and they will have a minimum of two tie wires cast in the concrete. Wrapping wires around the concrete centralizers to hold them in place is not an acceptable method of attachment. Any type of steel used as centralizers will be epoxy coated. The reinforcing steel cage will not be in contact with the bottom of the shaft. The elevation of the top of the reinforcing steel cage will be checked before and after the concrete is placed. If the reinforcing steel cage is not maintained within the specified tolerances, corrections to the cage support will be made by the Contractor, as required by the Engineer. No additional shafts will be constructed until the Contractor has modified the reinforcing steel cage support to prevent vertical movement, in a manner satisfactory to the Engineer. I.Installation of CSL Access Tubes: The Contractor will install CSL access tubes for CSL testing in all drilled shafts to permit access for the CSL test probes. The Contractor will install one CSL access tube for each 12 inches of shaft diameter with a minimum of 4 evenly spaced around the reinforcing cage. The CSL access tubes required in the plans without a corresponding bid item for CSL test are used for CSL testing of the drilled shaft if the Department deems the quality of the drilled shaft is suspect. The access tubes will be evenly spaced and securely attached to the interior of the reinforcement cage of the shaft as shown in the plans. The tubes will be as near to vertical and parallel as possible. Even moderate bending of the tubes will result in large regional variations of the data. The tubes will extend from 3 inches above the bottom of the drilled shaft to at least 4 feet above the construction joint. If the plans bottom of drilled shaft is lowered during drilling, the CSL tubes will also be extended. Under no circumstances will the tubes be allowed to rest on the bottom of the drilled excavation. During placement of the reinforcement cage, care will be exercised as to not damage the tubes. After placement of the reinforcement cage, the tubes will be filled with clean water as soon as possible and the tube tops capped to keep debris out. The tubes must be filled with water and capped before the pouring of the concrete, otherwise debonding of the access tubes from the concrete will occur resulting in data which indicates poor quality concrete. The Contractor will ensure the tubes remain filled until grouting occurs. Care will be taken during the removal of the caps from the pipes after installation so as not to apply excessive torque, hammering, or other stresses which could break the bond between the tubes and the concrete. J.Concrete Placement: Concrete must be continuously agitated in the hauling unit and be discharged within 105 minutes after the cement has been placed in contact with the aggregates for the first load and then 135 minutes after the cement has been placed in contact with the aggregates for all remaining loads. When the concrete temperature is 80°F or above, the time limitation will be reduced to the first load discharged within 75 minutes then 105 minutes for all remaining loads. The interval between batches will not exceed 30 minutes. 465 Page 348For delivery of concrete in remote locations where the preceding concrete delivery requirements will be difficult to meet, the Contractor may be allowed to use a set retarding admixture to control initial set when approved by the Engineer. When set retarding admixtures are allowed, the concrete delivery requirements may be adjusted with approval from the Department’s Concrete Engineer. The drilled shaft concrete will be placed immediately after the reinforcing steel cage is placed. Concrete placement will be continuous until the shaft is full and uncontaminated concrete flows out of the top of the shaft, as determined by the Engineer. The use of spud vibrators or other vibrating tools in the drilled shaft concrete will not be permitted. The free fall method of concrete placement is allowed for shafts 36 inches in diameter or greater provided that all of the following conditions are met: The water accumulation rate in the excavation is 3 inches or less per hour; There is no caving or sloughing of the excavation; The excavation is dewatered immediately prior to concrete placement such that there is no more than 3 inches of standing water in the bottom of the excavation; and, The concrete placement is directed through a hopper with a drop tube such that the concrete fall is vertical down the center of the shaft and the concrete is not allowed to hit the sides of the shaft or the reinforcing steel cage. K.Underwater Placement of Concrete : 1.Tremie: The tremie pipe will be a minimum of 0.25 inch thick wall steel pipe, with a minimum inside diameter of 7 3/4 inches for up to 6 foot diameter drilled shafts. The tremie pipe will be a minimum of 0.375 inch thick wall steel pipe, with a minimum inside diameter of 9 3/4 inches for drilled shafts larger than 6 foot diameter. The tremie pipe will be smooth and thoroughly cleaned of any hardened concrete, rust, and all other contaminants. The tremie pipe will be marked to allow determination of depth to the mouth of the tremie. Joints between sections of tremie pipe will be gasketed and bolted to be watertight under placement conditions. Instead of bolted joints, welded joints may be used if a smooth finish is maintained on the inside of the tremie pipe at the weld location. A crane or other lifting device will be available to remove the tremie from the water for resealing or horizontal relocation. Placement of underwater concrete will be a continuous operation. If an interruption of placement occurs, the interruption will not exceed 30 minutes without removal of the tremie and restarting the concrete placement according to the paragraph below. An interruption in concrete placement will not exceed the time for the concrete to change to a 4” slump or less. If the concrete attains the initial set before the concrete placement is completed, concrete placement will cease and the concrete in the shaft will be rejected and removed from the shaft. 465 Page 349Starting/Restarting of the concrete placement by tremie will begin by sealing the bottom of the tremie with a watertight seal before placing the tremie into the water. The watertight seal will prevent water from entering the tremie yet will be dislodged when concrete flow is initiated. The empty tremie pipe will be sufficiently heavy to be negatively buoyant when empty. The tremie pipe will be sealed, lowered to the bottom of the shaft or embedded at least 5 feet into the concrete, and completely filled with concrete. Fill the tremie slowly to avoid entrapped air and bridging. When full, the tremie will be slowly lifted 6 inches off the bottom to start concrete flow. The concrete supply will be continuous until soundings indicate the tremie has the required embedment. After being dislodged, the sealing device will either remain on the bottom or be retrieved by the Contractor. The mouth of the tremie will always remain embedded in the fresh concrete a minimum of 5 feet unless the tremie is being completely removed from the water. At no time will the concrete be allowed to fall through water. A tremie will not be moved horizontally while concrete is flowing through it. To relocate a tremie, lift it from the water, reseal, relocate, and restart as required above. All vertical movements of the tremie will be made slowly and will be carefully controlled to prevent loss of seal. If loss of seal occurs, placement through that tremie will be halted immediately. The tremie will be removed, resealed, replaced, and restarted as directed above. 2.Concrete Pump: Concrete pumps can be used for underwater concrete placement if surging of the pump line can be controlled to keep the pump line sufficiently embedded into the fresh concrete. If surging of the line cannot be controlled, a concrete pump will not be used. No reducers will be allowed from the pump truck to the tremie. The portion of the pump line that penetrates the deposited concrete will be a rigid steel line (pipe) at least the same diameter as the pump line. The rigid steel line (pipe) will have a minimum thickness of 3/16 inch. An approved plug will be inserted into the pump line, near the pump, in such a way that there is fresh concrete against the plug, with no air or water between the plug and concrete. The plug will be advanced down the pump line using pressure from the concrete pump to the bottom of the shaft. Placement will begin with the pump line within 6 inches of the bottom of the shaft. After pumping begins, the pump line will be kept within 6 inches of the bottom until soundings indicate that the pump line is embedded at least 5 feet into fresh concrete. The end of the pump line may be raised with the rising column of concrete as long as the end of the pump line remains embedded at least 5 feet into the concrete. At no time will the concrete be allowed to fall through water. Placement of concrete will be a continuous operation. Interruptions of placement will not exceed 30 minutes or the time of initial set of the concrete whichever is shorter. If the time of initial set is exceeded, the concrete will be rejected and removed from the shaft. 465 Page 350If the pump line is allowed to come out of or is removed from the concrete once placement has begun, restarting will require a tremie. Restarting of the concrete placement by tremie will begin by sealing the bottom of the tremie with a watertight seal before placing the tremie into the water. The watertight seal will prevent water from entering the tremie yet will be dislodged when concrete flow is initiated. The empty tremie pipe will be sufficiently heavy to be negatively buoyant when empty. The tremie pipe will be sealed, lowered to the bottom of the shaft or embedded at least 5 feet into the concrete, and completely filled with concrete. Fill the tremie slowly to avoid entrapped air and bridging. When full, the tremie will be slowly lifted 6 inches off the bottom to start concrete flow. The concrete supply will be continuous until soundings indicate the tremie has the required embedment. After being dislodged, the sealing device will either remain on the bottom or be retrieved by the Contractor. L.CSL Testing: The Contractor will coordinate CSL testing on all drilled shafts with a bid item for CSL test included in the plans. In addition, The Contractor will coordinate CSL testing on all drilled shafts without a bid item for CSL test if the Department deems the quality of the drilled shaft is suspect and the Department determines CSL testing necessary. Measurement and payment of any additional CSL testing will be in accordance with the measurement and payment portion of this specification. For the Department to determine if CSL testing is necessary, no subsequent work above the construction joint will be allowed for 7 days or until authorized by the Engineer, whichever comes first. All equipment, testing, and reporting procedures will be provided and performed in accordance with ASTM D6760 and the following: 1.Testing: The testing and analysis will be performed by an independent testing organization proposed by the Contractor and approved by the Engineer. The CSL testing will be performed after the shaft concrete has cured at least 48 hours. Additional curing time prior to testing may be required if the shaft concrete contains admixtures, such as set retarding admixture or water reducing admixture. The additional curing time prior to testing required under these circumstances will not be grounds for additional compensation or extension of time to the Contractor. After placing the shaft concrete and before beginning CSL testing of a shaft, the Contractor will inspect the access tubes. Each access tube that the test probe cannot pass through will be replaced, at the Contractor's expense, with a 1.5 to 2 inch diameter hole cored through the concrete for the entire length of the shaft. Location of the core hole will be determined by the CSL testing firm and will not damage the shaft reinforcement. Descriptions of inclusions and voids in cored holes will be logged and a copy of the log will be submitted to the Engineer. Findings from cored holes will be preserved, identified as to location, and made available for inspection by the Engineer. 2.Equipment: CSL equipment will consist of the following components: A digitizing card for conversion of analog CSL data to digital; 465 Page 351A microprocessor based CSL system for recording, processing, analyzing, displaying and log printing of digitally converted CSL data; Ultrasonic source and receiver probes capable of logging 1.5 to 2 inch I.D. pipes; An ultrasonic voltage pulser to excite the source combined with a synchronized triggering system to prompt the recording system; A depth measuring device used to correlate records with depth; and, Appropriate filter/amplification and cable systems for CSL testing. 3.Procedure: For the CSL test, information on the shaft bottom and top elevations and length, along with construction dates must be provided to the testing organization before or at the time of testing. Ultrasonic transmitter/receiver probes are then lowered to the bottom of a pair of access tubes. All slack is removed from the cable in order to assure accurate depth measurements. The two probes are then pulled simultaneously as to maintain a near horizontal ray path between them. Measurement will be made at 0.2 foot intervals or less as the probes ascend the tube pairs. This process is repeated for all test paths along the outer perimeter as well as across the inner diagonals of the shaft. The data is analyzed, and anomalies/defects characterized by longer travel times and lower signal amplitudes should be reported to the Engineer at the time of testing. 4.CSL Results: The CSL results will be presented in report form. Digitized raw data files will also be submitted with the report. This report will contain CSL logs and waterfall diagrams for each tube pair tested combined with an analysis of the first arrival time or compressional wave velocity and signal amplitude of the pulse versus depth. Any anomaly/defect zones will be discussed in the report where appropriate. The report will identify and provide detailed discussion of each anomalous zone detected by the CSL. Anomalous zones are areas where velocity reduction exceeds 20% of the shaft average velocity. Within these zones collect and process additional data to construct three-dimensional color-coded tomographic images with two-dimensional cross-sections between tubes within the anomalous zone. Upon completion of the CSL testing and acceptance of the drilled shaft by the Engineer, the water will be removed from the access tubes and any other drilled holes. The access tubes and drilled holes will then be completely filled with grout. The access tubes and drilled holes will be filled using grout tubes that extend to the bottom of hole. The access tubes will be cut off flush with the top of the drilled shaft M.Acceptance of CSL Tested Drilled Shafts : The acceptance of each drilled shaft will be the decision of the Engineer, based on the results of the CSL reports and other information about the shaft placement. De-watering and grouting of the access tubes and any subsequent work above the construction joint of the drilled shaft will not be done until after the acceptance of each shaft. The Engineer will provide a response to the Contractor within 5 business days after receiving the test results and analysis submittal. Rejection of the shaft based on CSL will require conclusive evidence that a defect exists in the shaft which will result in inadequate or unsafe performance under service loads. If the CSL records are complex or inconclusive the Engineer may require coring or excavation of the shaft to verify shaft conditions. If no 465 Page 352defect is encountered, the state will pay for all coring or excavation costs, including the grouting of all core holes. In the case that any shaft is determined to be unacceptable, the Contractor will submit a plan for remedial action to the Engineer for review. Any modifications to the foundation shafts and load transfer mechanisms caused by the remedial action will require calculations and working drawings stamped by a SD registered Professional Engineer for all foundation elements affected. All labor and materials required to perform remedial shaft action will be provided at no cost to the Department and with no extension of the contract time. N.Construction Tolerances: The following tolerances apply to drilled shafts: The drilled shaft will be within one twelfth of the shaft diameter or 3 inches, whichever is less, of the plan shown horizontal position, at the plan elevation of the top of the shaft. The bottom of the shaft will be drilled to the plan shown elevation, within a tolerance of plus or minus 6 inches. The vertical alignment of the shaft excavation will not vary from the plan alignment by more than 1/4 inch per 1 foot of depth or 3 inches of length or, whichever is less. After all concrete is placed, the top of the reinforcing steel cage will be no more than 6 inches above nor more than 3 inches below plan position. The diameter of the completed shaft will be the plan diameter with a tolerance of minus 0 inch, plus 2 inches. The top of the shaft will be built to plan elevation with a tolerance of plus or minus 1 inch. The plan shown elevation of the top of shaft will not be changed without prior permission from the Office of Bridge Design. Excavation equipment and methods will be designed so the completed shaft excavation will have a relatively flat bottom.
465.4METHOD OF MEASUREMENT
A.Class A45 Concrete, Drilled Shaft: The plan quantity will be the quantity paid for unless a change is ordered in writing. If a change is ordered, measurement will be according to neat line dimensions specified in the change and quantities computed to the nearest 0.1 cubic yard. B.Drilled Shaft Excavation: The plan quantity will be the quantity paid for unless a change is ordered in writing. If a change is ordered, measurement will be according to the neat line dimensions specified in the change and quantities computed to the nearest 0.1 cubic yard. C.Permanent Casing: The length of casing from the plan shown cutoff elevation to the bottom of the casing unless otherwise specified in the plans. Permanent casing will be measured to the nearest 0.1 linear foot, for each specified size of casing. 465 Page 353D.Crosshole Sonic Log (CSL) Test: CSL testing will only be measured once per shaft tested. The accepted quantity of CSL tests will be the plan quantity unless additional CSL testing is ordered by the Engineer. Measurement will be made only once per shaft tested. When no bid item for crosshole sonic log (CSL) test is included in the plans, the following will apply: If the CSL testing shows the shaft is sound with no anomalies, the Department will pay for the CSL testing by CCO. If the CSL test shows anomalies with the shaft, the Department will not make payment for the CSL testing or pay for the cost of any remedy necessary.
465.5BASIS OF PAYMENT
A.Class A45 Concrete Drilled Shaft: The accepted quantities of concrete will be paid for at the contract unit price per cubic yard. Payment will be full compensation for labor, equipment, tools, materials, and all incidentals required. All costs for furnishing, installing, cutting off, and grouting the CSL access tubes will be incidental to the unit price bid for Class A45 concrete drilled shaft. Payment will be for plan quantity regardless of the amount placed. If a change is ordered, payment will be for the changed quantity at the contract unit price. B.Drilled Shaft Excavation: The accepted quantities of excavation will be paid for at the contract unit price per cubic yard. Payment will be full compensation for labor, equipment, tools, materials, and all incidentals required, including blasting equipment and temporary casings. Payment will be for plan quantity regardless of the amount placed. If a change is ordered, payment will be for the changed quantity at the contract unit price C.Permanent Casing: The accepted quantities of casing will be paid for at the contract unit price per linear foot, for each specified size. Payment will be full compensation for labor, equipment, tools, materials, and all incidentals required. D.Crosshole Sonic Log (CSL) Test: Payment will be full compensation for all labor, equipment, tools, materials, services, and incidentals required to perform the tests and analyze the results. Payment will be made only once per shaft tested. 470 Page 354470 RAILING
470.1DESCRIPTION
This work consists of fabricating and constructing steel railings.
470.2MATERIALS
Materials will conform to the following sections: A.Structural Steel: Structural steel will conform to Section 970. Unless otherwise specified on the plans, structural steel for railing will conform to ASTM A709/A709M, Grade 36 except that hollow structural section members will conform to ASTM A500, Grade B. B.Bolts: Bolts, anchor bolts, and anchor rods will be as specified in the plans and will conform to C.Paint: Paint will conform to Section 411.
470.3CONSTRUCTION REQUIREMENTS
Railing will be fabricated and erected in accordance with Section 410.3 and the following: Unless otherwise specified in the plans, the Contractor will submit shop plans in accordance with the following: Prior to fabrication, the Contractor will submit shop plans to the Department for the Department’s opportunity for review. Any review by the Department of the shop plans is limited to general conformance with the contract plans and specifications only. The Contractor will send an email with the shop plans attached as a PDF to the Project Engineer and Office of Bridge Design. Upon request, the Project Engineer will provide the Contractor the appropriate email addresses. Within 14 calendar days of receiving the shop plans, the Office of Bridge Design will respond to the Contractor in one of the following ways: 1) No Exceptions Noted; 2) Returned for Revision; or 3) Not Required for Review. If the Department’s response states, “Returned for Revision”, the Contractor must make the revisions and resubmit the shop plans for review as specified above. The Contractor will not begin fabrication or construction of the work contained in the shop plans until the Department has confirmed, in writing, a completed review with a response of “No Exceptions Noted” or “Not Required for Review”. Railing will be constructed in accordance with the details shown and the shop plans and will be adjusted prior to bolting or welding the connections to ensure proper alignment at joints and throughout the railing length. Rail posts will be built vertical. Shop and field welding, and welding inspection will conform to the requirements in the latest edition of ANSI/AWS D1.1 or 1.5, whichever is applicable, Structural Welding Code. Welders will be qualified in accordance with Section 410.3 D. The painting of railing will conform to Section 411.