625.1-DESCRIPTION: The work of this section includes the furnishing of all materials and the construction of rock socketed drilled shaft foundations consisting of reinforced concrete placed within the drilled excavations. Each rock socketed drilled shaft foundation shall consist of an upper drilled shaft portion in a steel casing and a lower rock socket portion. 625.2-SUBMITTALS: The Contractor shall deliver all submittals required by this specification to the Engineer no later than one month prior to constructing any rock socketed drilled shafts shown in the plans. No rock socketed drilled shafts shall be constructed prior to the Engineer’s review and acceptance of all submittals. 625.2.1-Experience:
1.A satisfactory record of experience in rock socketed drilled shaft construction is of the utmost importance in obtaining a satisfactory rock socketed drilled shaft installation. The installation of the drilled shaft is required to be performed by a contractor or special ty subcontractor specializing in installing and having experience with rock socketed drilled shafts of similar length, diameter, and subsurface conditions as those shown in the contract documents.
2.The Contractor shall submit data on at least two projects performed during the past ten years, for which the Contractor, or Contractor’s key personnel who will be the on-site supervisor, have installed rock socketed drilled shafts of a range of diameters and lengths similar to those shown in the plans, in similar quantities, and under similar subsurface conditions. The list of projects shall contain names and phone numbers of owners ’ representatives who can verify the participation in those projects.
3.The Engineer shall review and approve the Contractor’s (Subcontra ctor’s) qualifications. If in the opinion of the Engineer the Contractor’s qualifications are not adequate, the Contractor shall submit to the Engineer a proposed method of obtaining the necessary qualifications.
4.The installation of all components of the drilled shaft including; drilling, reinforcement placement, concrete placement, and required wet hole condition work, casing installation and removal, slurry placement, and any other work required to complete the rock socketed drilled shaft, shall be performed by the approved contractor or specialty subcontractor. 625.2.2-Site Inspection: A signed statement shall be submitted affirming that the Contractor (or the Subcontractor if applicable) has inspected the project site and the available subsurface information including any available soil or rock samples. 625.2.3-Installation: The Contractor shall comply with applicable environmental regulations, including but not limited to the protection of river/stream water from degradation due to material excavated from rock socketed drilled shaft locations or due to other harmful erosion, protection of the environment from slurry spillage or discharge if slurry is used, and general environmental protection of the area from all operations related to rock socketed drilled shafts. The installation shall be in accordance with the Contractor’s proposed Safety Plan per Section 625.6.1.7. The Contractor shall provide a projected schedule of work to the Technical Support Division, DOHDrilledShafts@wv.gov, thirty (30) days in advance of construction of drilled shafts. This projected schedule will be used by the Technical Support Division to schedule preinstallation core hole drilling and drilled shaft inspection. 625.2.4-As-Built Records: Within 24 hours of the completed construction of each drilled shaft, the Contractor shall submit a report on the actual location, alignment, elevation, and dimensions of the drilled shaft, and will also submit a completed drilled shaft log. 625.3: Blank 625.4-DIMENSIONAL REQUIREMENTS: If the specified dimensional requirements are not met, the Contractor shall submit a corrective plan for any deviation from the drilled shaft location, alignment and elevation tolerances , and reinforcement dimensional requirements to the Engineer for approval. This approval may take up to fourteen (14) calendar days. The corrective plan shall be certified (signed by a Professional Engineer licensed in West Virginia knowledgeable in rock socketed drilled shaft installation). The cost of any corrective action shall be borne by the Contractor. 625.5-MATERIALS: 625.5.1-Concrete: Concrete for the rock socketed drilled shafts shall be Class DC and shall conform to the requirements of Section 601. The design 28 -day compressive strength shall not be less than 4500 psi unless shown otherwise in the Plans. The Contractor shall prepare a mix design in accordance with MP 711.03.23 to attain this strength. Slump for dry placement shall be seven (7) inches plus- or-minus one (1) inch. Unless otherwise specified in the Plans, the cement shall be Type I. For placement of concrete by tremie or pumping, the cement factor shall be increased by 94 lbs. from the original design cement factor, the slump shall be eight (8) inches plus-or- minus one (1) inch and shall maintain a slump in excess of four (4) inches throughout the concrete placement. 625.5.2-Reinforcing Steel: Reinforcing steel for main vertical bars and ties shall conform to Section 709.1, deformed type, grade 60. Reinforcing steel for use as spirals shall conform to Section 709.1, plain type, grade 60. 625.5.3-Casing: Metal casing shall be used in the u pper drilled shaft portion of the rock socket drilled shaft to prevent caving of the soil material or to exclude ground water. Casing shall be metal, of unit or sectional construction, be strong enough to withstand handling stresses, withstand the pressures of concrete and of the surrounding earth and ground water, and prevent seepage of water. Also, the casing used shall be selected by the Contractor to control dimensions and alignment of excavations within tolerances, to seal the casing into impervious materials, and to execute all other construction operations. Casing pipe used for permanent applications shall be new material and conform to ASTM A252, Grade 2. Casing pipe, when used for temporary applications only, will initially be required to meet the requirements of permanent pipe but when removed can be transferred to the contractor’s stock and reused on subsequent projects. Any required casing splices shall be welded with no interior splice plates, producing true and straight casing. All weld ing shall be in accordance with ANSI/AWS D1.1. Permanent casing is required in all drilled shafts where noted on the plans. All temporary casing shall be removed during placement of concrete unless otherwise noted on the plans. Should the Contractor be unable to remove the temporary casing or if conditions require the temporary casing remain in place, the Contractor shall pressure grout the annular space between the casing and soil. Materials and methods for grouting operation shall be submitted to the Engineer for approval for the grouting operation. There shall be no additional cost to the Division for the grouting operation. 625.5.4-Crosshole Sonic Logging (CSL) Testing Tubes: Tubes required for CSL Tests shall be ASTM A53, Grade B, nominal two (2) inch diameter. Hydrostatic test requirements are waived. Threaded Couplings shall be used per ASTM A865. 625.5.5-Thermal Integrity Profiler (TIP) Wires: Wire, equipment, and testing procedure shall conform to ASTM D7949, Method B. 625.6-CONSTRUCTION: The following sequence describes a generalized construction method that is expected to be appropriate for the installation of the rock socketed drilled shafts. Deviations will be permitted with the Engineer’s approval.
a.Contractor shall provide suitable access to the “Preinstallation Core Hole” location at each rock socketed drilled shaft.
b.Drilling of a “Preinstallation Core Hole” will be performed by the Division* as specified in subsection 625.7.2.1.
c.Drilling of cased hole through the soil overburden down to top of competent rock. Seating bottom of casing to minimize entry of ground water.
d.Drilling of rock socket to the minimum diameter shown in the plans and to an elevation shown on the drawings or otherwise directed by the Engineer.
e.Determination of wet or dry hole condition, by the Division*, as specified in subsection 625.7.2.2.
f.Inspection of drilled hole for plumbness, by the Division*, as specified in subsection 625.7.2.3.
g.Cleaning of the drilled hole by the Contractor, particularly the rock socket and the inside face of the casing, as specified in subsection 625.7.2.5.
h.Inspection of the drilled shaft sidewall and bottom cleanliness, by the Division* as specified in subsections 625.7.2.4 and 625.7.2.5.
i.Placement of the pre-assembled cage of reinforcing steel with CSL tubes and/or TIP wires and securing it in place against movement during concreting and during casing withdrawal, as specified in subsection 625.6.2. It also must be secured in such a way that the minimum clear cover over the bars is maintained.
j.Placement of concrete in either dry or wet conditions. The temporary casin g shall be withdrawn carefully and slowly so as not to leave any voids in the concrete and so as not to dislocate any reinforcing steel. Any concrete not meeting this specification ’s slump requirements will be rejected.
k.Curing, stripping, and finishing shall be the same as for other structural concrete. Casing may be used as forms.
l.Inspection of the concrete, by the Division* as specified in subsection 625.7.2.6.
m.Corrective measures for any unacceptable drilled shaft, removal of water from the CSL tubes and filling with an approved grout. All core holes, as specified in subsection 625.7.3, must be filled with an approved grout. * For Design Build / Alternative Project Delivery projects, the Design Build Team are responsible for the testing, however all notifications to the Division are required. 625.6.1-Excavation: 625.6.1.1-Scope: The Contractor shall perform all excavations required for the drilled shafts and the rock sockets, through whatever materials are encountered, to the dimensions shown in the plans, or required by the site conditions, or directed by the Engineer. The Contractor shall make each drilled shaft excavation available to the Engineer for inspection, providing tools, equipment, and safety me asures as hereinafter specified. Based on preinstallation core hole information or on general inspection of the rock socket, the Contractor shall drill the rock socket deeper if directed by the Engineer. 625.6.1.2-Excavation through Overburden: Unless otherwise shown in the plans, rock socketed drilled shaft excavations in the overburden shall be vertical bored holes extending from the ground surface down to the surface of competent rock. Temporary or permanent casings shall be required down to the competent rock surface and be seated in rock in a manner that prevents caving and minimizes the entry of ground water. In the event of a groundwater condition, appropriate measures shall be taken subject to the Enginee r’s approval. Such measures may include pumping from within the excavation, external dewatering, or excavation through a slurry-filled hole until the casing can be seated and sealed. 625.6.1.3-Excavation in Rock: Rock sockets shall be excavated to the dimensions and depths shown in the plans, forming a bearing area at the bottom of the socket, flat to within a tolerance of ½ inch per foot. Each socket shall be excavated into continuous rock for the indicated length. Blasting methods will not be permitted. The top elevation of competent rock must be confirmed as the socket drilling is started. The effective “top elevation” is based on observation of the boundary zone where broken or weathered rock becomes competent rock and is also in fluenced by the presence of any shale or coal seams. Based on that elevation, and the information from the preinstallation core hole, the Engineer will determine the final depth of socket and bottom elevation. Upon completion of each rock socket excavation, the Engineer may (1) accept the socket, or (2) order deeper excavation based upon preinstallation core hole data or general inspection of the socket. The adequacy of each socket will depend on the soundness of its bottom surface and on the soundness of its underlying layers. Contractor is cautioned not to over-drill the rock sockets. Unauthorized over-drilling will be at the Contractor’s expense. In the case where over-drilling would bring the drilled shaft base too close to a coal seam or other weak layer, then drilling must be extended through such weak layer, at the Contractor’s expense, to a satisfactory deeper bearing level as determined by the Engineer. No portion of the rock socket shall be exposed to drilling fluid or groundwater for more than 96 hours. Any portion of the rock socket exposed to drilling fluid or water for more than 96 hours, and any portion of the rock socket which, in the opinion of the Engineer, has deteriorated due to exposure to air or water, shall be reamed with an approved grooving tool to a depth of not less than ¼ inch, or as directed by the Engineer. Reaming of the socket, if necessary, is considered incidental to the cost of drilling the rock socket, and no separate payment will be made for this work. 625.6.1.4-Providing for Socket Inspection: Upon completion of the excavation of each rock socket, and upon mechanical cleaning of the socket, the Contractor shall make the socket available to the Engineer for inspection, as specified in subsection 625.7. 625.6.1.5-Disposal of Materials: Disposal of excavated materials shall be accomplished under the general provisions of Section 207.6. 625.6.1.6-River/Stream Area: Rock socketed drilled shaft construction in the river/stream shall employ whatever special methods the Contractor finds necessary for access and for accomplishing the work. These methods may include cofferdams, temporary causeway, or other suitable measures. The Contractor will be responsible for conforming to all regulatory and environmental requirements related to the river/stream and for obtaining any permits that are required by their river/stream operations. 625.6.1.7-Safety Measures: Safety of all persons is to be considered an objective of the utmost importance on all projects. Ther efore, the Contractor shall take whatever measures are necessary to protect their own personnel, subcontractors’ personnel, the Engineer or other agents of the state, regulatory personnel, and others including the general public. The following list is presented as representative of issues that the Contractor must address. It is not intended as all -inclusive and does not relieve the Contractor of conforming to other regulations, laws, requirements, or other measures reasonably required for safe excavating operations. The Contractor shall develop a safety plan in accordance with these requirements and provide this plan to the Engineer for their review.
a.Any required equipment within an excavation shall be operated by air or electricity. The use of gasoline-driven engines or diesel engines within an excavation will not be permitted. All lighting shall be electric, and precautions shall be taken regarding potential short circuits of electric current within ground water.
b.The Contractor will take precautions to assure that no explosive or noxious gases are present. Fresh air shall be supplied into the excavation and foul air shall be removed whenever any personnel are present in the hole.
c.A safety harness or chair lift, with separate safety line, protective cage, and two-way radio communication shall be used for any entry into an excavation.
d.No open excavation shall be left unattended. During non-working hours excavations shall be protected using solid, safe covers that are firmly fastened in place. 625.6.2-Reinforcing Steel Installation: Prior to installation of reinforcing steel, the steel cage shall be checked and cleaned of any materials that would tend to prevent bonding. The excavated hole shall also be checked, and any remaining or newly depo sited debris shall be removed. Immediately upon the Engineer’s approval of the condition of the cage and acceptance of the socket, and just prior to placement of concrete, the fully assembled cage of reinforcing steel shall be installed into the excavation. The cage will consist of longitudinal (vertical) bars, spiral or tie bars, cage stiffener bars as required, spacing devices, and any other appurtenances required to maintain alignment, shape, and clearances. Cages shall include steel tubes and TIP wires in shafts where CSL and TIP testing is to occur as outlined in subsection 625.6.2.1. Each cage shall be placed in one unit by lowering into the hole in a manner that will prevent distortion. Concrete spacers or other approved noncorrosive spacing devices shall be used at sufficient intervals (near the bottom and at intervals not exceeding ten (10) feet along the rock socketed drilled shaft) to ensure concentric spacing for the entire cage length. The minimum number of centering devices at each level shall be three. All steel centering devices with less than three (3) inches of concrete cover shall be epoxy coated. The cage shall be supported from the top by use of a ground surface frame or other positive means. Setting the cage on the socket bottom without support will not be permitted. The Contractor may, with the approval of the Engineer, remove the top support after sufficient concrete has been placed to adequately support the cage vertically and prevent distortion or racking of the cage. The bottom of the reinforcing steel cage shall be a minimum of three (3) inches and a maximum of twenty-four ( 24) inches from the bottom to the rock socketed drilled shaft excavation. Additional clearance may be approved by the Engineer. All intersections of rock socketed drilled shaft reinforcing steel shall be tied with cross or “figure 8” ties. The reinforcing steel in the drilled shaft shall be 100% tied and supported so that the reinforcing steel will remain within allowable tolerances for position. Unless otherwise shown in the plans, splicing shall be by mechanical connectors or couplers which develop at least 125% of yield strength of the reinforcing bar. No more than 50% of the longitudinal reinforcing shall be spliced within 60 bar diameters of any lappe d splice location or within two (2) feet of any mechanical splice or coupler location. Cage stiffener bars shall be used as required to provide a reinforcement cage of sufficient rigidity to prevent racking, permanent deformations, etc. during installation. If the concrete is to be placed by the free -fall method, these bars must first be removed. In the event that the rock socketed drilled shaft has been excavated below the anticipated tip elevation, the reinforcing cage may be extended at the tip (bottom) end by lap splices, mechanical connectors, or welded splices in conformance with the Standard Specifications. In this instance, splices need not be staggered and 100% of the reinforcing bars may be spliced at a given location. Lap splice lengths shall be as shown in the plans or approved by the Engineer. Prior to placing the reinforcement cage, the Contractor shall demonstrate to the satisfaction of the Engineer that the fabrication and handling methods to be used will result in a reinforcing cage placed in the proper position, with the proper clearances, and without permanent bending or racking of the reinforcement cage. The elevation of the top of the steel cage shall be checked before and after the concrete is placed. If the rebar cage is not ma intained within the specified tolerances, corrections shall be made by the Contractor to the satisfaction of the Engineer. No additional drilled shafts shall be constructed until the Contractor has modified the reinforcement cage support system in a manner satisfactory to the Engineer. 625.6.2.1-Contractor Preparation for Testing: To accommodate the CSL and TIP test requirements, the Contractor shall install the appropriate number of tubes and/or TIP wires in each drilled shaft to be tested. The number o f tubes and wires per drilled shaft shall be as tabulated below: TABLE 625.6.2.1 Drilled Shaft Diameter Number of CSL Tubes Number of TIP wires Tube / Wire Spacing Less than 42” 3 0 120º 42” to ≤ 60” 4 0 90º > 60” to ≤ 96” 6 6 60º Greater than 96” 8 8 45º The tubes shall be per subsection 625.5.4. Each tube shall have a round, regular internal diameter free of defects or obstructions including defects or obstructions at pipe joints; in order to permit the free, unobstructed passage of 1½ inch diameter source and receiver probes. The tubes shall be watertight and free from corrosion with clean internal and external faces to ensure passage of the probes inside and a good bond with the concrete outside. Each tube shall be fitted with a watertight shoe on the bottom and a removable cap or plug on the top. The tubes shall be securely attached to the interior of the reinforcing steel cage. The tubes are typically wire-tied to the reinforcing cage every forty (40) inches, or otherwise secured such that the tubes stay in position during placement of the cage and during placement of concrete. The tubes shall be installed in each shaft in a regular, symmetric pattern such that the tube spacing in degrees will correspond to that shown in the table above. The tubes shall be as near to parallel as possible. They shall extend from six (6) inches above the drilled shaft bottom to at least forty (40) inches above the drilled shaft top. No tube may be allowed to rest on the bottom of a drilled excavation. If the drilled shaft top is sub- surface, then the tubes shall extend at least two (2) feet above the ground surface or above the water surface if the ground surface is below water. Any joints required to achieve full length tubes shall be made watertight. The Contractor shall investigate all CSL tubes, making sure that there are no bends, crimps, obstructions or other impediments to the free passage of the testing probes. A record of the tube lengths, including a note of the projection of the tubes above the top of the shaft shall be made. The Contractor shall provide information on the shaft bottom and top elevations, length and construction dates to the Engineer prior to the CSL tests. Care shall be taken during placement of the reinforcing steel cage so as not to damage the tubes. After placement of the cage, and before placement of concrete, the tubes shall be filled with clean water and the tube tops shall be capped or sealed to keep debris or other foreign matter out of the tubes. Care shall be exercised in the removal of caps or plugs so as not to apply excess torque, hammering, or other stresses that could break the bond between the tubes and the concrete. The TIP wires shall be per subsection 625.5.5. 625.6.3-Placement of Concrete: Method of placement shall be determined by measuring the water infiltration rate into the shaft as specified in Section 625.7.2.2. Concrete placement for wet hole shall be placed by tremie. Free fall placement shall be permitted for dry hole condition, except that free fall height shall not exceed five (5) feet unless the concrete is placed using a drop chute or centering device. Free fall height is not restricted as long as a drop chute or centering device is used, and the concrete is directed down thro ugh the center of the shaft without directly hitting the reinforcing cage or the sides of the hole. Dry hole shall not have more than three (3) inches of water in the bottom of hole at start of concrete placement. Prior to concrete placement, the Contractor shall make all necessary arrangements to ensure the uninterrupted delivery of concrete so that there will not be any cold joints in the dri lled shafts. Placement of concrete shall generally conform to the applicable portions of Section
601.10 The rate of placement of concrete, as related to the height of fresh concrete at any
time, will be subject to the Engineer’s approval. The placement method will be developed by the Contractor, taking account of set’time, hydraulic pressures and casing removal. All costs of replacement of defective drilled shafts shall be the responsibility of the Contractor and shall be at no cost to the Division. After the concrete level has reached the required top elevation, it shall be forced to overflow in the case of tremie or pump placement, leaving only fresh, uncontaminated concrete. In the case of placement by free fall (dry conditions), the concrete shall be continued high enough to compensate for any settlement due to removal of casing. The top ten (10) feet of each rock socketed drilled shaft shall be vibrated except when more than ten (10) feet is to be exposed above the ground line or the riverb ed/streambed, then the entire exposed portion shall be vibrated. The concrete shall not be vibrated until after any temporary casing is removed. Exposed portions of each rock socketed drilled shaft shall be cured in accordance with Section 601.12. 625.6.4-Removal of Casing: Removal of the casing from a shaft may occur gradually as concrete is placed. Insofar as possible, casing extraction shall be done at a slow uniform rate by application of a steady vertical upward pull in the direction of the axis of the shaft. To facilitate extraction, tapping on the casing, exertion of temporary downward pressure, slight rotation, or the controlled use of a vibratory hammer will be permitted, but care must be taken to avoid harmful impacts or disturbances to the fresh concrete. Vibration or rodding may not be used to break the casing loose for extraction. If, during extraction of casing, upward movement of concrete and/or reinforcing steel occurs, the Engineer shall be notified immediately. If the Engineer considers the movement to be minor, then the extraction of the casing may continue. If, however, the movement is deemed significant and indicative of squeezing of the surrounding soil thus resulting in a reduction of the drilled shaft diameter, then the Engineer may order the casing to be left in place, or permit extraction to proceed and order a later non-destructive load test, or may order other procedures as appropriate at no additional cost to the Division. For the upper portions of rock socketed drilled shafts that will be exposed and visible, the casing may remain in place as a form until the concrete has attained a strength that enables it to stand alone without further deformation. Casing shall then be removed. 625.7-INSPECTION OF SOCKETS: 625.7.1-Inspection: The Engineer will inspect the shaft as outlined in subsections 625.7.2.4 and 625.7.2.5. Time required for inspection will be considered incidental to the work and will not be cause for extra compensation related to a claim or extension of contract time. 625.7.2-Division Testing: 625.7.2.1-Preinstallation Core Holes: The Contractor shall provide notice to the Technical Support Division via e -mail (DOHDrilledShafts@wv.gov) when each site is ready for drilling. The Division will commence drilling of the preinstallation core hole within 5 working days after notification from Contractor that site has suitable access for drilling. A preinstallation test boring will be drilled by the Division at each rock socketed drilled shaft location, or as shown on the plans, to determine the character of the material that the rock socketed drilled shaft extends through and the material that is at the base of the shaft in order to ensure the material along and below the tip of the rock socket is capable of carrying the load that will be imposed on it. The preinstallation borings are to be drilled prior t o beginning excavation for each representative rock socketed drilled shaft. The Contractor shall provide all work necessary to allow access for the drill rig to the preinstallation test boring location, which at a minimum shall include constructing drill pads and access roads. Unless otherwise directed, the preinstallation test borings are to be extended a minimum depth of two (2) upper drilled shaft diameters but not less than ten (10) feet below the planned tip elevation of the rock socketed drilled shaft shown on the plans. Standard Penetration Testing (SPT) and sampling shall be performed at five (5) foot intervals in the preinstallation borings in accordance with AASHTO T 206. Rock coring will be performed in accordance with ASTM D2113 using a wireline core barrel system and will commence immediately upon obtaining an SPT value of 50 blows per six (6) inches or less on bedrock. The recovered core sample size will be approximately two (2) inch diameter (NX or NQ size). Additional preinstallation test borings in other locations may be required where directed by the Engineer. Test boring logs of each preinstallation boring will be prepared by the Division and will be provided to the Contractor within three (3) working days of completion of the test boring. The preinstallation test borings logs will describe the type and thickness of all soil and rock layers, and locate the presence of groundwater, open joints, voids, soft rock, or other deleterious material. All recovered soil and rock samples shall be maintained by the Division and stored on site at suitable location, provide d by the Contractor, until completion of the project. Within 10 working days after completion of preinstallation core hole, the Engineer will notify the Contractor of the final tip elevations for each drilled shaft location. 625.7.2.2-Wet or Dry Hole De termination: The Division will check the depth of water at the bottom of the drilled shaft. If the depth does not increase by more than twelve (12) inches over a 1 -hour period, the hole will be considered dry. Otherwise, the hole will be considered wet. 625.7.2.3-Plumbness: Contractor shall provide notice to the Technical Support
Division vi — a e -mail (DOHDrilledShafts@wv.gov) five (5) working days prior to the date
each drilled shaft will be ready for inspection. Plumbness of the rock socketed drilled shaft/rock socket shall be measured by the Division by measuring the geometry of the drilled shaft excavation using SHAPE, Sonicaliper, or other suitable means. For any rock socketed drilled shaft, the maximum permissible deviation from plumb shall be 1.5% measured with respect to the vertical axis at the center of the drilled shaft excavation. The Contractor shall provide suitable access and means for lowering inspection equipment into the drilled shaft excavation. For any rock socketed drilled shaft at its top, the maximum deviation of the center shall be three (3) inches from its project plan location. The maximum deviation of the finished top of shaft from the plan elevation shall be minus one (1) inch or plus three (3) inches. An absolute minimum cover of three (3) inches to the reinforcing steel is strictly required. In the event of any deviations in the dimensional requirements, the contractor shall not proceed with construction of pier columns or cap until submission and approval of a corrective plan has been granted. 625.7.2.4-Rock Sock Sidewall Inspection: Contractor shall provide notice to the Technical Support Division via e-mail (DOHDrilledShafts@wv.gov) five (5) working days prior to the date each drilled shaft will be ready for inspection. The Division will inspect the rock socket side walls with a downhole camera or other suitable device. The Engineer shall evaluate the rock quality and construction, as outlined in 625.6.1.3. 625.7.2.5-Shaft Bottom Cleanliness: Contractor shall provide notice to the Technical Support Division via e-mail (DOHDrilledShafts@wv.gov) five (5) working days prior to the date each drilled shaft will be ready for inspection. The contractor shall clean the rock socket so tha t a minimum of 75% of the base will have less than ½ inches of sediment at the time of placement of the concrete. Sediment depth at any location shall not exceed 1 ½ inches. The Division shall determine shaft cleanliness by using a mini-SID, SQUID, or other suitable device. The contractor shall use an air-lift to achieve the required bottom cleanliness. The contractor shall begin concrete placement in the shaft within 3 hours after the shaft bottom cleanliness is approved. If concrete placement in the drilled is not started within 3 hours, the rebar cage shall be removed, and hole shall be re-inspected at no additional time to the Contractor or cost to the Division. 625.7.2.6-In-place Concrete Quality Testing: The Contractor shall furnish and place the Crosshole Sonic Logging (CSL) tubes and thermal integrity profiler (TIP) wires in all drilled shafts. The number of tubes and tip wires to be used shall be as specified in subsection 625.6.2.1. The Division will perform the testing and provide a repor t of the drilled shaft integrity testing to the Contractor. The CSL tubes shall remain open in the shaft and be grouted by the Contractor after acceptance of that shaft. 625.7.2.6.1-Crosshole Sonic Logging (CSL): The nondestructive testing method known as CSL shall be used on any rock socketed drilled shaft which is constructed with the placement of concrete under wet conditions or as required in the plans. The testing shall not be conducted until at least three (3) calendar days after placement of concrete is concluded in the drilled shaft and will be completed within fourteen (14) calendar days after such placement. The CSL tests shall be conducted in conformance with ASTM D6760 and by a testing company approved by Technical Support Division. The Contractor shall comply with the scheduling and notification requirements for drilled shaft construction outlined in Section 625.2.3 by contacting the following Technical Support Division e-mail address: (DOHDrilledShafts@wv.gov). This will allow Technical Support Division to provide a qualified company to perform testing within the time frames allotted for in this subsection. 625.7.2.6.1.1-CSL Testing Results: The CSL test results will be compiled into a drilled shaft integrity testing report for each drilled shaft. The report will summarize and analyze any defect zones indicated on the logs. A copy of each report will be provided to the Contractor. 625.7.2.6.1.2-Evaluation of CSL Test Results: The Engineer will review the report and, if the report determines that the drilled shaft is acceptable, will submit to the Contractor in writing within seven (7) calendar days approval to proceed with the work. The rating of the rock socketed drilled shaft integrity will consider the increases in first arrival time (FAT) and the energy reduction relative to the FAT or energy in a nearby zone of good concrete. The criteria for rating the concrete from the CSL test will be: TABLE 625.7.2.6.1.2 Rating Criteria Good (G) FAT increases 0-10% and energy reduction < 6 db Questionable (Q) FAT increases 11-20% and energy reduction < 9 db Poor / Flaw (P/F) FAT increases 21 to 30% or energy reduction of 9 to 12 db Poor / Defect (P/D) FAT increases 31% or more or energy reduction >12 db Flaw or defect zones as indicated in Table 625.7.2.6.1.2 will be indicated on the logs and listed in a table within the r eport. The flaw or defect zones and their horizontal and vertical extent will be discussed in the report text. Flaws will be addressed by the Division if they affect more than 50% of the tested tube pairs at the same depth. Defects will be addressed by the Division if they affect two or more of the tested tube pairs at the same depth. At a minimum, addressing flaws and defects will include Crosshole Tomography (CT). If it is determined that the rating is less than Questionable, based on the results of the CSL and CT testing, the Division will require core drilling and sampling by the Contractor for further evaluation of the flaw or defect at no additional cost to the Division. The diameter, number, depth, and location of cores shall be as directed by the Engineer. The acceptance of each drilled shaft shall be the decision of the Engineer, based on the results of the drilled shaft integrity testing report and other information on the drilled shaft placement. Rejection of a drilled shaft shall require conclusive evidence that a defect exists in the drilled shaft, which will result in inadequate or unsafe performance under service loads. If the Non-Destructive Testing records are complex or inconclusive, the Engineer will require the Contractor to verify drilled shaft conditions by core drilling. If a flaw or defect is confirmed, the Contractor shall pay for all coring and grouting costs. If no flaw or defect is encountered, compensation for all coring and grouting will be in accordance with subsection 104.3 and 109.4. 625.7.2.6.1.3-Remedial Action: In the case that any rock socketed drilled shaft is determined to be unacceptable, the Contractor shall submit a plan for remedial action to the Engineer for approval. The approval or rejection of the rem ediation plan may take up to fourteen (14) calendar days. If the remediation plan is rejected the Contractor shall revise the plan and submit it for approval and the approval time is restarted. Any modifications to the rock socketed drilled shaft and load transfer mechanisms caused by the remedial action will require calculations and working drawings stamped by a Professional Engineer licensed in the State of West Virginia for all foundation elements affected. All labor and materials required to perform remedial drilled shaft action shall be provided at no cost to the Division and with no extension of the contract time. 625.7.2.6.2-Thermal Integrity Profiler (TIP): Perform TIP testing using the embedded thermal wire array, and in accordance with the ASTM D7949 (method b). Thermal integrity profiling is performed to evaluate shaft integrity and location of the reinforcing cage. The number of wires to be used shall be as specified in subsection 625.6.2.1. Thermal wire cables shall b e connected to a thermal access port (TAP) immediately following casting. The Contractor shall provide cooperative assistance and labor as required to assist the
Division i — n inspecting the thermal wires prior to concreting the shaft. Prior to TIP testing,
the contractor shall provide shaft installation details to the TIP consultant. Because the method relies on the heat of hydration, tip testing is generally performed between 8 and 48 hours of concrete placement (note the optimum TIP testing time is dependent on shaft size and concrete mix and could range from 4 to 72 hours). 625.7.2.6.2.1-Criteria to be used for acceptance or rejection of rock socketed drilled shaft using TIP testing: The rating of the shaft integrity using tip shall consider variations in temperature as measured by the thermal wires. Potential local anomalies may be indicated by locally low temperatures relative to the average temperature at that depth, or average temperatures significantly lower than the average temperatures at other depths. The criteria for rating the concrete from the TIP test shall be: Satisfactory (s) = 0 to 6% effective radius reduction and cover criteria met Anomaly (a) = effective radius reduction > 6% or cover criteria not met When a tested shaft is categorized as anomaly (a), slices modeled at the area of question may be provided so that a structural evaluation of the shaft can be performed prior to implementing any corrective measures. Core drilling shall be performed to investigate problem areas found during TIP testing. 625.7.3-Evaluation by Core Drilling: A rock socketed drilled shaft that is found to be unacceptable shall be core drilled by the Contractor in accordance with ASTM C42. Cores shall be four (4) inch nominal diameter. One or mo re core holes shall be drilled at the location(s) as determined by the Engineer. An accurate log of the core shall be kept, and the core shall be crated and properly marked showing the drilled shaft depth at each interval of core recovery. The core and one copy of the coring log shall be provided to the Engineer. The Engineer shall determine if the rock socketed drilled shaft is acceptable. The Engineer will submit to the Contractor in writing within seven (7) calendar days approval to proceed with the work. If the quality of the drilled shaft is determined to be unacceptable, then the Contractor shall proceed in accordance with subsection 625.7.2.6.1.3. 625.8-METHOD OF MEASUREMENT: Rock socketed drilled shafts and Rock Socket foundations will be measured by the linear foot. For payment purposes, the drilled shafts are the portion from the finished top of each rock socketed drilled shaft to the top of competent rock. Rock Socket is the portion from the top of competent rock to the bottom of the drilled shaft rock socket as shown in the plans or as directed by the Engineer. Each measured drilled shaft is to be complete in place, accepted, and ready to function. "Top of drilled shaft" is the top of concrete as shown in the plans. "Top of competent rock" is as tabulated in the drilled shaft schedules in the plans unless a difference of one (1) foot or more is found during drilling. 625.9-BASIS OF PAYMENT: The accepted quantities of rock socketed drilled shaft foundations, measured as provided above, will be paid for at the contract unit price per linear foot; complete in place including excavation, slurry if required, temporary or permanent metal casing, steel reinforcing, concrete, curing, and any required forming and finishing. No additional payment will be made for temporary casing that remains in place and pressure grouting due to the Contractor ’s inability to stabilize a drilled excavation, for the need to place concrete by tremie or pumping, for the need to use slurry for drilling, or for extra excavation and concrete that may be required due to drilling diameters larger than the minimum diameters specified. No additional payment will be made for methods employed to gain access to rock socketed drilled shaft construction or for means required to provide a dry working environment within the drilled shafts. Tubes for CSL testing, TIP wires, and other responsibilities related to testing and inspection assistance are incidental, with no separate payment being made.
625.10 Pay Items:
ITEM DESCRIPTION UNIT 625001-* Drilled shaft “D” Diameter Linear Foot 625003-* “D” Rock Socket Linear Foot * Sequence number D = Diameter of shaft, in inches
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Source: Standard Specifications for Roads and Bridges, 2023 Edition. Pages 508–521 of 1,006. View official source ↗