SECTION PRESTRESSED ROCK ANCHORS

Transcription

1 SECTION PRESTRESSED ROCK ANCHORS PART 1 GENERAL 1.1 REFERENCES A. The following is a list of standards which may be referenced in this section: 1. ASTM International (ASTM): a. A153, Standard Specification for Zinc Coating (Hot-Dip) on Iron and Steel Hardware. b. A181, Standard Specification for Carbon Steel Forgings, for General-Purpose Piping. c. A307, Standard Specification for Carbon Steel Bolts and Studs, 60,000 psi Tensile Strength. d. A615, Standard Specification for Deformed and Plain Billet-Steel Bars for Concrete Reinforcement. e. A653, Standard Specification for Steel Sheet, Zinc-Coated (Galvanized) or Zinc-Iron Alloy-Coated (Galvannealed) by the Hot-Dip Process. f. A722, Standard Specification for Uncoated High-Strength Steel Bar for Prestressing Concrete. g. A882, Standard Specification for Epoxy-Coated Seven-Wire Prestressing Steel Strand. h. A924, Standard Specification for General Requirements for Steel Sheet, Metallic-Coated by the Hot-Dip Process. i. B117, Standard Practice for Operating Salt Spray (Fog) Apparatus. j. C33, Standard Specification for Concrete Aggregates. k. C117, Standard Test Method for Materials Finer than 75 micrometer (No. 200) Sieve in Mineral Aggregates by Washing. l. C150, Standard Specification for Portland Cement. m. C309, Standard Specification for Liquid Membrane-Forming Compounds for Curing Concrete. n. C939, Standard Test Method for Flow of Grout for Preplaced-Aggregate Concrete (Flow Cone Method). o. C942, Standard Test Method for Compressive Strength of Grouts for Preplaced-Aggregate Concrete in the Laboratory. p. C1107, Standard Specification for Packaged Dry, Hydraulic-Cement Grout (Nonshrink). q. D92, Standard Test Method for Flash and Fire Points by Cleveland Open Cup PRESTRESSED ROCK ANCHORS

2 1.2 DEFINITIONS r. D95, Standard Test Method for Water in Petroleum Products and Bituminous Materials by Distillation. s. D512, Standard Test Method for Chloride Ion in Water. t. D566, Standard Test Method for Dropping Point of Lubricating Grease. u. D610, Standard Test Method for Evaluating Degree of Rusting on Painted Steel Surfaces. v. D638, Standard Test Method for Tensile Properties of Plastics. w. D3350, Standard Specification for Polyethylene Plastics Pipe and Fittings Materials. x. D4101, Standard Specification for Propylene Plastic Injection and Extrusion Materials. y. D4289, Standard Test Method for Elastomer Compatibility of Lubricating Greases and Fluids. z. D4327, Standard Test Method for Anions in Water by Chemically Suppressed Ion Chromatography. A. Alignment Load: Nominal load maintained in anchor to keep testing equipment positioned. B. Anchor: System used to transfer tensile loads to concrete or rock. Includes prestressing steel, anchorages, grout, coatings, sheathings, provisions for sounding the top of the primary grout, provisions for installing grout and venting air, and couplers if used. C. Anchor Load: Load to which the anchor is stressed. D. Centralizers: Spacers used to position tendon in center of anchor hole and to space the individual tendons in a particular pattern to ensure uniform grout cover for tendon. E. Consolidation Grout: Portland cement grout that is injected into the hole prior to inserting tendon to seal or stabilize hole. F. Creep Movement: Total movement that occurs during creep test of anchor. G. Creep Test: Test to determine movement of tendon at constant load during certain time period. H. Design Load: Anticipated final maximum effective load in anchor after allowance for time-dependent losses PRESTRESSED ROCK ANCHORS

3 I. Double Corrosion Protection: Protection of tendons wherein the first layer of protection is provided by primary grout or secondary grout, and the second layer is as specified in this section. J. Elastic Movement: Recoverable movement of anchor measured during performance test. K. Leveling Grout: Nonshrink grout used for bedding and leveling tendon anchorage bearing plate. L. Lift-Off Test: Checking force in prestressed anchor at any specified time with use of hydraulic jack. M. Performance Test: Incremental test loading and unloading of tendon anchorage recording of movement of tendon at each increment. N. Primary Grout (or Anchor Grout): Grout that is injected into anchor hole to provide anchorage of tendon prior to stressing. O. Primary Grout Zone: That section of the anchor that is grouted before stressing. P. Proof Load: Temporary prestressing load in anchor at force level greater than its design load for testing purposes. Q. Proof Test: Incremental test loading of tendon anchorage, recording of tendon movement at each load increment. R. Redrilling: Removal of consolidation grout from a tendon hole. S. Residual Movement: Nonelastic (nonrecoverable) movement of anchor measured during performance test. T. Secondary Grout: Grout that is injected into anchor hole after stressing to cover length of prestressed anchor above the primary grout, providing corrosion protection for high strength steel. U. Secondary Grout Zone: That section of the anchor that is stressed before grouting. V. Set Time: Time between start of mixing grout and liquid phase changing into plastic state. W. Sheathing: Enclosure around the prestressing steel to avoid bonding between the and the surrounding grout or to provide corrosion protection PRESTRESSED ROCK ANCHORS

4 X. Sounding: A method used by the CONTRACTOR to lower a rigid wire, bar, or pipe through a hole in the stressing head to physically touch the top of the primary grout and determine the actual elevation for comparison with the maximum elevation permitted. Y. Tendon: Complete anchor assembly (excluding grout) consisting of stressing anchorage and high strength prestressing steel, with sheathing and coating when required. Z. Tendon Manufacturer: Company supplying the high strength steel or bars. AA. Test Load: Temporary prestressing load in anchor at force level equal to 1.33 times design load. BB. Topping Grout: Nonshrink grout used to fill in stressing anchorage blockout after secondary grouting is completed and excess tendon lengths are cut off. CC. Transfer (Lockoff) Load: Post-tensioning force (Kips) per anchor transferred to the anchor plate when the lockoff devices are set and jack load is released. DD. Water Test: Testing of a drilled hole using water to determine watertightness of the hole. 1.3 SUBMITTALS A. Shop Drawings: 1. Manufacturer s Product Data: a. Prestressed Anchors: Material specification, load capacities, creep data, mill test certificates, and installation procedures. b. Post-Tension System: Material specification. c. Sheathing: Corrugated or extruded, if specified. d. Leveling and topping nonshrink grout. e. Admixtures. 2. Post-Tension System: a. Tendon Design, Details, and Calculations: Include size, number, and type of tensioning elements, anchorages, bearing plates, pipe sleeves, other related hardware, fabrication and erection details. b. Primary and Secondary Grout Piping: Details on grouting simultaneously inside and outside of the corrugated group sheath. c. Proposed method to provide the extruded polypropylene sheath a watertight seal with the base of the anchor head. d. Structural and Stressing Calculations: Include allowances for increase in stressing length resulting from development of tendon anchorage at the top of the primary grout and time-dependent loss of load values PRESTRESSED ROCK ANCHORS

5 e. Top Anchorage and Bearing Plates: Design and details. Show incorporation of specified functions. f. Final Tendon Assembly: Include corrugated group sheath and method and control of insertion rate into hole. g. Grout and Vent Tube: Arrangement details. h. Tendon Anchorages: Detailed stressing procedures and data required for performance testing and proof testing. 3. Special Reinforcing Steel: Design and details at tendon anchorages. B. Information Submittals: 1. Schedule showing sequence of grouting operation. 2. Qualifications: a. Installer s experience records. b. System designer. c. Testing laboratory. 3. Post-Tension System: a. Installation instructions. b. Certification of conformance. c. Onsite storage instructions. 4. Prestressing Steel: Source of materials. a. Steel Manufacturer s Mill Certification: 1) Physical and chemical properties including stress-strain curves, steel area, guaranteed ultimate tensile strength, yield strength, elongation at yield, and estimated values for relaxation characteristics of steel. 2) Include one report per run and identify system, showing disposition of materials onsite. 5. Steel Reinforcement: Manufacturer s test data. 6. Grouts: Mix design, trial batch test results, and field test reports. 7. Grout Admixtures: Manufacturer s mixing and installation instructions. 8. Certification that grouts and admixtures do not contain chlorides, aluminum powder, or other corrosive elements for the prestressing. 9. Installation Details: Grout pipe and primary grout arrangement, sounding procedures, and grout pumping. 10. Procedures: Determine and verify drilled hole tolerances. 11. Hydraulic Jack and Gauge: Calibration certification. 12. Certification of Proper Installation: Each anchor installed. 13. Anchor hole record data. 14. Grouting record data. 15. Submit record document tensioning, testing, and lift-off data applicable to tendon, including plot of performance tests showing total anchor movement as a function of load and a plot of residual movement as a function of load. 16. Nonshrink Grout: Manufacturer s warranty PRESTRESSED ROCK ANCHORS

6 1.4 QUALIFICATIONS A. Installer: Minimum of 5 years acceptable experience involving type of post-tensioning system. Available onsite, full-time, during entire drilling, grouting, and prestressing operations. B. System Design and Shop Drawing Preparation: Performed by a professional civil or structural engineer currently registered in the state of Utah, who will stamp and sign Shop Drawings. C. Testing Laboratory: Independent, certified to perform grout cube strength testing in accordance with ASTM C REFERENCE MATERIALS A. Make available onsite one copy of the Post-Tensioning Manual, 5th Edition (1990), published by the Post-Tensioning Institute (PTI). 1.6 GROUT PREINSTALLATION MEETING A. Attended by CONTRACTOR s quality control representative, manufacturer s representative, Subcontractor(s), and employees performing the grouting operation. B. Purpose: Manufacturer s representative will demonstrate recommended techniques for mixing and pumping grout by mixing and pumping grout into at least two tendon holes. 1.7 RECORD DOCUMENTS A. Anchor Hole Record Data: Record the following: 1. Elevation of concrete-rock interface during anchor hole drilling. 2. Hole deviation from vertical or straight line and the amount. 3. Anchor hole water testing, consolidation grouting, and redrilling. 4. Tendon installation. 5. Grout strength testing, fluidity tests, set time tests, as specified for each type of grout. 6. Primary tendon grouting, tensioning, and tendon testing with plots of anchor movement as a function of load. 7. Sounding measurements and elevation of top of primary grout. 8. Secondary tendon grouting. 9. Lift-off data. 10. Date of certification of installation by manufacturer s representative PRESTRESSED ROCK ANCHORS

7 B. Grouting Operation Data: Record for each tendon installed. 1. Type of mixer. 2. Amount of water added per bag. 3. Measured temperature of rock in the hole. 4. Grout pressure. 5. Strength test cube sample designations. 6. Test results showing specific gravity, flow cone test, mud balance, and bleed test data. 7. Volume of primary grout placed. 8. Elevation at top of primary grout measured. 9. Time and date. 10. Volume of bag of grout mix. 1.8 DELIVERY, STORAGE, AND HANDLING A. Protect uncoated or otherwise unprotected tendon components with vapor-phase corrosion inhibitors and wrap or cover at factory to prevent damage and to prevent dirt, water, and rust from affecting components during shipping storage and up until time of installation. B. Materials showing rust sufficient to cause excessive surface roughness, pitting visible to naked eye, or unevenness will be considered defective and will be rejected. 1.9 SEQUENCING AND SCHEDULING A. Complete consolidation grouting of all drilled anchor holes prior to installing relief wells in spillway foundation in accordance with Section 02502, UNDERDRAIN SYSTEM. B. Complete required prerequisites to rock anchor installation activities as follows: Activity Product shipments (1) Approval of the grout mix design, and (2) approval of the minimum primary grout cure time Grouting operation Prerequisites Submittals approval or acceptance by CONSTRUCTION MANAGER CONSTRUCTION MANAGER s acceptance of certified trial batch test results (1) Accepted related Submittals, and (2) grouting preinstallation meeting PRESTRESSED ROCK ANCHORS

8 Activity Tendon tensioning Secondary grouting Topping grout placement Starting drilling, grouting, and tensioning operations Prerequisites (1) Approval of the grout mix design, (2) approval of the minimum primary grout cure time, (3) Primary grout and anchor plate leveling grout have cured for minimum specified time, (4) grout strength has been verified by certified testing laboratory, and (5) hydraulic jack and gauge calibration certification (1) Tendon alignment stressing for individual strand, (2) Tendon performance test, (3) Tendon proof test, and (4) Tendon certification of proper installation Complete within 1 week of cutting tendon protrusions 2-week written notification to CONSTRUCTION MANAGER PART 2 PRODUCTS 2.1 SYSTEM DESIGN A. Design: Meet requirements of Recommendations for Prestressed Rock and Soil Anchors in Post-Tensioning Manual published by Post-Tensioning Institute (PTI), except requirements of these Specifications and Drawings will take precedence over PTI publication. B. Design anchorage and blockout requirements. C. Size tendon holes when required size exceeds minimum shown or specified. D. Detail tendon anchor lengths subject to requirements shown. E. Provide centralizers to center tendons in holes. F. Special Reinforcing Steel: Design at tendon anchorages as necessary. G. Performance Specification: 1. Maximum Tendon Stress: 80 percent of Guaranteed Ultimate Tensile Strength (GUTS). 2. Tendon Transfer (Lockoff) Load: Not to exceed 70 percent of GUTS. 3. Minimum requirements for each tendon at design load level, and with maximum allowable tendon hole bond stress allowable at any load level, as shown PRESTRESSED ROCK ANCHORS

9 4. Design Load: Not to exceed 60 percent of GUTS after losses. 2.2 REINFORCING STEEL A. Steel Reinforcement: 1. Conform to ASTM A615, Grade Bar Splices: Capable of developing 125 percent of bar yield strength. 2.3 PRESTRESSED ANCHOR TENDONS (GALVANIZED) A. Provide complete assembly including prestressing steel, grouted fixed anchorage, and stressing anchorage. B. Steel Thread Bars: 1. Deformations of Thread Bars: a. Form screw thread suitable for mechanically coupling lengths of thread bar and for positive attachment of anchor assemblies. b. Meet ASTM A722 requirements and be uniform such that any length of bar may be cut at any point and internal threads of a coupling designated for that size of bar can be freely screwed on bar. 2. Tensile and Physical Properties: a. Nominal Diameter: inches. b. Ultimate Tensile Stress: Minimum 150,000 psi. c. Yield Stress at 0.2 Percent Offset: Minimum 120,400 psi. d. Elongation in 10-Bar Diameter: Minimum 7 percent. e. Nominal cross-section area of square inch for inch diameter. f. Nominal Bar Weight: 5.56 pounds per foot for inch diameter. g. Weight of Zinc Coating: Minimum 0.85 ounce per square foot. h. Carbon Content: Maximum 0.55 percent. 3. Thread bars with quenched or tempered steels are not permitted. 4. Provide products from manufacturers with minimum 5 years experience, under their current name, in manufacturing of post-tensioning material. 5. Bars and their deformations shall be hot-rolled. 6. Manufacture to meet requirements of ASTM A722, including supplementary requirements of ASTM A722. When testing in accordance with ASTM A722, provide minimum of four Samples from material from each heat and test two Samples in tension and two Samples in bend test. 7. Components: Provide couplers, nuts, bearing plates, and other system components as required for complete installation PRESTRESSED ROCK ANCHORS

10 8. Manufacturer and Product: Dywidag Systems International, USA, Inc., Bolingbrook, IL; Dywidag Prestressed Thread Bar Tendon System. C. Top Anchorage and Bearing Plates: 1. Design and fabricate of steel to dimensions sufficient to prevent permanent physical distortion when tested with tendon of size required. 2. Bearing Plate: a. Design: Meet requirements of AISC Steel Construction Manual, 8th Edition. b. Size: Base on bearing stress allowed for concrete strengths as shown and within requirements of 1985 printing of PTI Post- Tensioning Manual, Edition 4, Paragraph 3.1.7, page Design special reinforcement in concrete at tendon anchorage required for performance of anchorage. 4. Couplers for Bars: a. Screw-on type as furnished by bar manufacturer. b. Capable of developing specified guaranteed minimum tensile strength of bars without evidence of failure. 5. Design anchorages to develop at least 95 percent of actual ultimate strength of tendon, tested in an unbonded state, without exceeding anticipated set. 6. Design anchorage to allow verification of prestress force in tendon prior to removal of stressing equipment. D. Splices in Bar Tendons: As approved by CONSTRUCTION MANAGER in accordance with Article SUBMITTALS. E. Centralizers: As required to ensure that specified clearance between tendon and grout hole is maintained. F. Post-Tensioning Units: Do not weld; perform any necessary welding in vicinity of tendons or tendon materials with extreme caution to avoid touching tendon with electrode and to avoid electrical circuits that may cause resistance heating of tendon. G. Grout and Vent Tubes: 1. Designed by tendon manufacturer for coordination with holes required in baseplate and proper grouting procedures. 2. Coordinate with methods for sounding top elevation of primary grout. 3. Make provision to remove water from bottom of hole if present. 4. Verify drill hole size to receive anchor and, if this hole size is required to be of larger diameter than that shown to allow placement of tubes, grout, and sounding devices, show larger diameter on Shop Drawings PRESTRESSED ROCK ANCHORS

11 5. Provide a minimum of 1/2-inch diameter tube at centerline of tendon to be used to sound top of primary grout using a positive rigid or semirigid measuring rod to extend down to top of grout. 6. Sounding Device: Positive rigid measuring rod or wire. 2.4 PORTLAND CEMENT 2.5 WATER 2.6 SAND A. ASTM C150, Type II. B. Fresh, without lumps or other indication of hydration or pack set. A. Clean and meeting Federal and State Drinking Water Standards with regard to oil, acid, alkali, organic matter, and injurious quantities of chlorides, fluorides, sulphites, and nitrates. A. Fine aggregate for concrete as specified by ASTM C33. B. Not more than 4 percent passing U.S. Standard No. 200 sieve when tested in accordance with ASTM C GRANULAR FILLER A. Size: As designated by CONSTRUCTION MANAGER in field. B. Gradation: Meeting requirements of ASTM C LEVELING AND TOPPING GROUT MIX A. Nonmetallic, nongas liberating, fluid, prepackaged nonshrink grout with natural aggregate. B. Meet requirements of Corps of Engineers Specification for Non-Shrink Grout, CRD-C621, and ASTM C1107, Grade B. C. Fluid Grout: Fluid consistency (20 to 30 seconds), as determined by flow cone test, CRD-C611 or ASTM C939. D. Strength: Minimum cube strength of 2,500 psi at 1 day and 7,000 psi at 28 days as determined by CRD-C621 OR ASTM C942. E. Manufacturers and Products: 1. Master Builders, Cleveland, OH; Master Flow PRESTRESSED ROCK ANCHORS

12 2. Euclid Chemical Co., Cleveland, OH; Hi-Flow Grout. 2.9 WATER REDUCING PLASTICIZER ADMIXTURES A. Manufacturers and Products: 1. W. R. Grace and Co., Cambridge, MA; WRDA Master Builders, Inc., Cleveland, OH; Rheobuild CURING COMPOUND A. ASTM C309. B. Moisture Loss: Not to exceed gram per square centimeter per 72 hours. C. Manufacturers and Products: 1. Masters Builders, Cleveland, OH; Masterkure. 2. Euclid Chemical Co., Cleveland, OH; Euco Super Floor Coat CONSOLIDATION GROUT MIX A. Composition: Portland cement, Type II, sand and water. B. Minimum Compressive Strength: 3,500 psi at 14 days. C. Water-Cement Ratio: Determined by CONTRACTOR. D. Water Loss: Control by use of granular filler as required by CONSTRUCTION MANAGER GROUT FOR PRIMARY AND SECONDARY GROUTING OF SINGLE BAR UNITS A. Fluid, prepackaged, nonshrink grout requiring only addition of water. B. Extended working time, fluid for at least 1 hour with fluid consistency of 20 to 30 seconds per flow cone test of CRD-C611. C. Pumpable nonshrink, nonmetallic, nonbleeding, and nongas forming. D. Provide certification grout contains no chlorides or other elements corrosive to prestressing steel. E. Strength: Minimum cube strength of 2,500 psi at 1 day and 7,000 psi at 28 days when sampled and tested per ASTM C PRESTRESSED ROCK ANCHORS

13 F. Manufacturers and Products: 1. Master Builders Co., Cleveland, OH; Master Flow Euclid Chemical Co., Cleveland, OH; Hi-Flow Grout DOUBLE CORROSION PROTECTED POST TENSIONING SYSTEM A. First Layer of Protection: Primary or secondary grout. B. Second Layer of Protection: Centralized bare prestressing steel strand or bars in primary and secondary grout zones and encapsulated in grout inside a corrugated polyvinyl chloride (PVC), polypropylene or polyethylene group sheath in the primary grout zone and a smooth PVC tubing in the secondary grout zone. Group sheath extended the full length of hole and covered with grout. C. Epoxy Coating: ASTM A882. D. Corrugated Sheathing: 1. Wall Thickness: Sufficient to protect against corrosion, prevent movement during tendon stressing, and to transfer the stress to the rock. Either polypropylene or polyethylene, at CONTRACTOR s option. 2. Polypropylene: Designation Type PP210B , ASTM D4101. a. Manufacturer and Model: Ashland Chemical Co.; PROFAX 6823 and Polyethylene: High-density polyethylene cell Classification , ASTM D3350. E. Corrosion Inhibitor: 1. Drop Point: 300 degrees F minimum, ASTM D Flash Point: 300 degrees F minimum, ASTM D Water Content: 0.1 percent maximum, ASTM D95, E1. 4. Oil Separation: 0.5 percent by weight maximum at 160 degrees F, FTMS 791B, Method Corrosion Test: 5 percent salt fog at 100 degrees F, 5 mils (Q panel Type S); normal conditions, rust Grade 7 or better after 720 hours; aggressive conditions, rust Grade 7 or better after 1,000 hours; ASTM B117 and ASTM D610, E1. 6. Soak Test: 5 percent salt fog at 100 degrees F, 5 mils (Q panel Type S), immerse panels in 50 percent salt solution and expose to 5 percent salt fog, no emulsification after 720 hours; ASTM B Water Soluble Ions: a. Chlorides: 10 ppm maximum, ASTM D512. b. Nitrates: 10 ppm maximum, ASTM D PRESTRESSED ROCK ANCHORS

14 c. Sulfides: 10 ppm maximum, APHA 427D (15th Ed.). 8. Sheathing Hardness and Volume Change: 10 percent maximum for volume, 15 percent maximum for hardness after 40 days at 150 degrees F, ASTM D Sheathing Tensile Strength Change: 30 percent maximum after 40 days at 150 degrees F, ASTM D Manufacturer and Product: Viscosity Oil Co.; VISCONRUST SOURCE QUALITY CONTROL A. Performed by independent testing laboratory. B. Grout Mixes: Mix a trail batch of proposed grout mix design and test grout strength using 2-inch cubes cured and tested per ASTM C Trial Batch: Use actual cement and actual water that will be used at site. Test cubes 28 days and proposed cure primary grout prior to scheduled tensioning of tendons. PART 3 EXECUTION 3.1 DRILLING EQUIPMENT A. Coring, rotary drilling, or percussion hammer type. 3.2 GROUTING EQUIPMENT A. Continuous operation without interruption. B. Mixer: High speed colloidal type mixer with a water meter for precise control. Provide dispensers with accurate controls for all admixtures. C. Pumps: Progressive cavity type, capable of pumping grout as required to match working time of grout. 1. Measure pumped grout quantity within 0.1 cubic foot. 2. Pressure: 150 psi at top of hole. D. Screen: 1. Clear Openings: inch maximum size. 2. Easily accessible for inspection and cleaning PRESTRESSED ROCK ANCHORS

15 E. Testing Equipment: Provide flow cone (for checking fluidity), containers (to check bleeding of grout), and cube molds (for sampling, clamping, and sealing of cube samples). Provide a mud balance (for maintaining the correct specific gravity and admixture and water-cement ratio). 1. Dog Leg: A steel mandrel, 10 feet long and 1 inch smaller in diameter than anchor hole (for checking diameter and straightness of drilled hole). 3.3 TENDON TENSIONING EQUIPMENT A. Hydraulic Jacks: 1. Pressure Gauge: a. Reading Dial: At least 6 inches in diameter and accurate enough to read 100 psi changes in gauge pressure. b. Calibrated as unit with jack cylinder extension in approximate position for final jacking force within three weeks prior to stressing. 2. Capable of applying each load increment in less than 60 seconds. B. Incremental Measuring Devices: Capable of detecting tendon movement to nearest inch. 3.4 DRILLING A. Follow approved procedures and document elevation of concrete-rock interfacing. B. General: 1. Either coring, rotary drilling, or percussion-air-hammer type drilling. 2. Use water or air with sufficient moisture for dust control to remove drill cuttings. 3. Do not use rod dope, grease, or other lubricants during drilling. 4. Do not cause permanent structural damage to existing concrete sections. 5. If permanent damage occurs, discontinue method of drilling and substitute another method at no additional cost. 6. Repair structural damage by approved method. C. Drill holes with appropriate size bit or core with diameter of bit or core not less than 1/8-inch smaller than designed or specified hole diameter. D. Consolidation Grouting and Redrilling: Perform when watertightness test fails as specified hereinafter PRESTRESSED ROCK ANCHORS

16 E. After completion of drilling, wash sides of holes with a nozzle that will impinge water on sides of hole. F. During washing, provide water velocities in hole sufficient to remove loose material from hole. G. If a hole is rejected by CONSTRUCTION MANAGER, due to failure to maintain required alignment or due to any fault or negligence of CONTRACTOR, fill hole with consolidation grout. Drill new hole in location determined by CONSTRUCTION MANAGER. H. Test holes drilled for installation of tendons for watertightness as specified hereinafter. I. Drilled Holes: After acceptance of hole, close each hole with a tapered, turned wooden plug to prevent entry of unwanted grout, dirt, or other deleterious substance prior to installation of assemblies and grouting. J. Anchor Hole Tolerances: 1. Depth: Within minus 0 inch to plus 6 inches. 2. Location: Within 1 hole diameter from planned location. 3. Verticality: Within 1-degree of vertical. 3.5 CONSOLIDATION GROUTING A. Maximum 5 psi gauge measured at hole top. B. Maintain pressure on grout until initial set. C. Initial Setting Time: Minimum 8 hours prior to redrilling. 3.6 TENDON INSTALLATION AND PRIMARY GROUTING A. Preparation: Immediately prior to tendon installation, flush hole with water to provide saturated rock and concrete surfaces, remove standing water in bottom of hole, and sound hole for compliance with required depth. B. Tendons: 1. Free of dirt, loose rust, grease, or other deleterious substances. 2. Place in accordance with approved Shop Drawings. 3. Provide with rigid and adequate support during placement of primary grout. 4. Do not weld. Perform welding in vicinity of tendons or tendon materials with extreme caution to avoid touching tendon with electrode and to avoid electrical circuits that may cause resistance heating of tendon PRESTRESSED ROCK ANCHORS

17 C. Primary Grout: 1. Pump into bottom of hole through clean and leak-free grout pipes. 2. Grout area outside and inside the corrugated group sheath simultaneously. Maintain primary grout at the same level both inside and outside of group sheath. 3. Measure amount being pumped to avoid overfilling hole. 4. Continuously sound the primary grout surface by positive measuring rod through the holes in tendon baseplate to verify that grout is at correct elevation and is not higher than shown or approved. 5. Keep grout pipe below grout surface to avoid entrapping air. D. If top elevation of primary grout exceeds specified elevation by 1 foot or more, perform following remedial action: 1. Remove tendon, flush hole, and redrill if necessary or remove grout to the required elevation. 2. Replace tendon with new tendon if damaged. E. After primary and anchor plate leveling grout operation is complete, allow tendon to remain undisturbed until grout has cured for the time required to reach minimum specified strength, as determined by ASTM C942. F. Tolerance: Minimum 0.50-inch grout cover for tendons. 3.7 TENDON STRESSING A. Do not tension tendon before primary grout and anchor plate leveling grout have cured for minimum specified time and grout strength, required by design and as shown on approved Shop Drawings or in calculations, has been verified by testing laboratory when cured at appropriate temperatures. B. Tension tendon by means of equipment required and furnished by tendon manufacturer. C. Conduct so that tension being applied and elongation of prestressing steel may be measured at all times. D. Monitor tensioning with incremental measuring devices. E. Modify blockouts to access tendon bearing plate or a jack chair to allow physical checking of end anchorage at lift-off PRESTRESSED ROCK ANCHORS

18 3.8 SECONDARY GROUTING A. Successfully complete the following prior to starting tendon secondary grouting: 1. Tendon stressing. 2. Tendon performance test. 3. Tendon proof test. 4. Tendon approval by CONSTRUCTION MANAGER. B. After acceptance of tendon by CONSTRUCTION MANAGER, install secondary grout mix both inside and outside group sheath. C. Grout Pipes: Keep below grout surface to avoid entrapping air. 3.9 CUTTING OF TENDON PROTRUSIONS A. Perform upon completion of anchor installation and certification of proper installation by manufacturer s representative. B. Cut that portion of anchor tendon protruding beyond stressing anchorage in accordance with tendon manufacturer s representative s recommendations LEVELING AND TOPPING GROUTING A. Upon completion of anchorage blockout, fill blockout with leveling grout. B. Upon completion of tendon protrusion cutting, fill blockout for tendon anchorage to the surface with topping grout. C. Resin Bonding Agent: Place on the sides of the anchorage prior to placement of the topping grout. D. Match surface of topping grout to surrounding surface and coat with curing compound FIELD QUALITY CONTROL A. Conduct in CONSTRUCTION MANAGER s presence. B. Perform at least one set of specified tests during each grouting phase for each anchor hole. C. Watertightness Test: 1. Fill drilled hole with water and subject water to a pressure of 5 psi (11.5 feet) in excess of the hydrostatic head as measured at top of hole PRESTRESSED ROCK ANCHORS

19 2. Maximum Leakage Rate: gallon per inch diameter per foot depth of hole per minute. 10-minute minimum test duration. 3. Consolidation grout holes failing leakage rate for the entire length of the hole and redrill. 4. Retest and repeat process until acceptable leakage test. 5. Adjacent Holes: Observe during test to detect inter-hole connections. 6. Consolidation grout holes to seal inter-hole connections and retest. D. Sounding: Perform prior to tendon stressing and prior to final hardening of the primary grout. E. Grout Test: ASTM C942, use clamped and sealed molds. Perform strength tests, mud balance (specific gravity) tests, fluid (flow cone) tests, and bleed tests. F. Tendon Performance Test: 1. Performance test one anchor prior to installing other anchors to verify all design assumptions, including anchor length. Select a tendon with a design load closest to average of other tendons for the performance test. 2. Incrementally load and unload anchor per performance test schedule. 3. At each increment, record gauge reading and movement of tendon to nearest inch with respect to an independent fixed reference point. 4. Measure anchor load with pressure gauge calibrated with the jack. 5. P = Design load for anchor; (not to exceed 60 percent of guaranteed ultimate strength of tendon). 6. AL = Alignment load; refer to Shop Drawings (use monojack to set strand). 7. Performance Test Schedule: a. AL. b P. c. AL. d P. e P. f. AL. g P. h P. i P. j. AL. k P. l P. m P. n P. o. AL. p P PRESTRESSED ROCK ANCHORS

20 q P. r P. s P. t. AL. u P. v P. w P. x P. y P test load (10-minute hold). z. AL. aa. Adjust to lockoff load. 8. Transfer (Lockoff) Load: Not to exceed 70 percent of Guaranteed Ultimate Tensile Strength (GUTS) of tendon (refer to approved Shop Drawing for transfer load information). 9. Anchor tendon may be completely unloaded prior to lockoff, if circumstances warrant, as final stressing then does not require further movement readings. 10. Hold load at each increment, just long enough to obtain movement reading. 11. Except for reading of residual movement at AL, no movement readings need to be taken during unloading of anchor. 12. Test Load: Hold for 10 minutes. a. Record total movements with respect to a fixed reference point at 1 minute, 2, 3, 4, 5, 6, and 10 minutes. b. If total movement between 1 minute and 10 minutes exceeds 0.04 inch (1 mm), hold test load for an additional 50 minutes. c. Record total movements at 15 minutes, 20, 25, 30, 45, and 60 minutes. d. Repump hydraulic jacks used to test anchors as required to maintain pressure during the creep test. 13. Take lift-off reading after transferring load to end anchorage and prior to removing jack. 14. Lift-Off Load: Within 5 percent of desired transfer load. 15. If lift-off load is less than 95 percent of transfer load, reset end anchorage and make another lift-off reading. G. Tendon Proof Test: 1. Perform on all anchors. 2. Incrementally load anchor per proof test schedule below. 3. At each increment, record movement of tendon to nearest inch ( cm) with respect to an independent fixed reference point. 4. Measure anchor load with pressure gauge calibrated with jack. 5. P = Design load for anchor shall not exceed 60 percent of guaranteed ultimate strength of tendon; see anchor schedule on Drawings PRESTRESSED ROCK ANCHORS

21 6. AL = Alignment load (use monojack to set each strand). 7. Proof Test Schedule: a. AL. b P. c P. d P. e P. f P. g P test load (10-minute hold). h. AL. i. Adjust to lockoff load. 8. Anchor tendon may be completely unloaded prior to lockoff, if circumstances warrant and final stressing will then not require further movement readings. 9. Transfer (Lockoff) Load: Not to exceed 70 percent of the GUTS; refer to approved Shop Drawing for transfer load information. 10. Hold load at each increment just long enough to obtain movement reading, but not more than 1 minute. 11. Test Load: Hold for 10 minutes. a. Record total movements with respect to a fixed reference point at 1 minute, 2, 3, 4, 5, 6, and 10 minutes. b. If movement between 1 minute and 10 minutes exceeds 0.04 inch (1 mm), maintain test load for 50 minutes or more. c. Record additional anchor movements at 15 minutes, 20, 25, 30, 45, and 60 minutes. d. Repump hydraulic jacks used to test anchors as required to maintain pressure during the creep test. e. Compare proof test results to performance test results. 12. After transferring load to end anchorage and prior to removing jack, make a lift-off reading. 13. Lift-Off Load: Within 5 percent of the desired transfer load. 14. If lift-off load is less than 95 percent of transfer load, reset end anchorage and make another lift-off reading. H. Anchor Acceptance Criteria: 1. Performance Test: Total elastic movement should exceed 80 percent of theoretical elastic elongation of stressing length and be less than theoretical elastic elongation of stressing length plus 50 percent of bond length. 2. Proof Test: Total movement between 50 percent of design load and test load, should exceed 80 percent of theoretical elastic elongation of free stressing length for this respective load range. 3. Initial Lift-Off Reading: Shows anchor load within 5 percent of specified lockoff load PRESTRESSED ROCK ANCHORS

22 3.12 MANUFACTURER S SERVICES A. Inspect and approve onsite tendon and grout and sounding system fabrication and assembly prior to installation. B. Be present onsite during tendon installation and grouting of at least the first five tendons. C. Be present during tendon tensioning, performance and proof testing, and liftoff checks for at least the first five tendons. D. Make necessary documentation to provide Manufacturer s Certificate of Proper Installation. END OF SECTION PRESTRESSED ROCK ANCHORS