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B-1 APPENDIX B Proposed LRFD Construction Specifications for Soil Nail Walls TABLE OF CONTENTS 1.1 DESCRIPTION .............................................................................................................................................. B-3 1.2 MATERIALS.................................................................................................................................................. B-3 1.2.1 Facing ............................................................................................................................................... B-3 1.2.1.1 Cast-in-place Concrete ................................................................................................... B-3 1.2.1.2 Reinforcing Steel ............................................................................................................ B-3 1.2.1.3 Permanent Shotcrete ....................................................................................................... B-3 1.2.1.4 Architectural Surface Finishes ....................................................................................... B-3 1.2.2 Soil Nails .......................................................................................................................................... B-3 1.2.2.1 Solid Soil Nail Bar .......................................................................................................... B-3 1.2.2.2 Bar Coupler..................................................................................................................... B-4 1.2.2.3 Fusion-Bonded Epoxy Coating ...................................................................................... B-4 1.2.2.4 Encapsulation.................................................................................................................. B-4 1.2.3 Soil Nail Appurtenances ................................................................................................................... B-4 1.2.3.1 Centralizer ...................................................................................................................... B-4 1.2.3.2 Grout ............................................................................................................................... B-4 1.2.3.3 Fine Aggregate................................................................................................................ B-4 1.2.3.4 Portland Cement ............................................................................................................. B-4 1.2.3.5 Admixtures ..................................................................................................................... B-5 1.2.3.6 Film Protection ............................................................................................................... B-5 1.2.4 Bearing Plates, Nuts, and Head-Stud Shear Connectors .................................................................. B-5 1.2.4.1 Bearing Plates ................................................................................................................. B-5 1.2.4.2 Nuts................................................................................................................................. B-5 1.2.4.3 Shear Connectors ............................................................................................................ B-5 1.2.5 Welded-Wire Mesh........................................................................................................................... B-5 1.2.6 Reinforcing Steel .............................................................................................................................. B-5 1.2.7 Geocomposite Sheet Drain ..............................................................................................................B-5 1.2.8 Underdrain and Perforated Pipe........................................................................................................ B-6 1.2.8.1 Pipe ................................................................................................................................. B-6 1.2.8.2 Fittings ............................................................................................................................ B-6 1.2.9 Temporary Shotcrete ........................................................................................................................ B-6 1.3 CONTRACTOR QUALIFICATIONS ........................................................................................................... B-6 1.4 SUBMITTALS ............................................................................................................................................... B-6 1.4.1 Personnel .......................................................................................................................................... B-6 1.4.2 Surveys ............................................................................................................................................. B-7 1.4.3 Construction Plan ............................................................................................................................. B-7 1.5 STORAGE AND HANDLING ...................................................................................................................... B-8 EXCAVATION .............................................................................................................................................. B-8 1.6 1.7 SOIL NAIL INSTALLATION ....................................................................................................................... B-9 1.8 GROUTING.................................................................................................................................................... B-9 1.9 SOIL NAIL TESTING ................................................................................................................................... B-9 1.9.1 Tests.................................................................................................................................................. B-9 1.9.2 Equipment......................................................................................................................................... B-9

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B-2 Section xx – Soil Nail Walls 1.10 VERIFICATION TESTING .........................................................................................................................B-10 1.10.1 Methods ..........................................................................................................................................B-10 1.10.2 Schedule .........................................................................................................................................B-10 1.11 PROOF TESTING ........................................................................................................................................B-11 1.11.1 Methods ..........................................................................................................................................B-11 1.11.2 Schedule .........................................................................................................................................B-12 1.12 ACCEPTANCE CRITERIA OF TEST SOIL NAILS .................................................................................B-13 1.13 REJECTION OF TEST SOIL NAILS ..........................................................................................................B-13 1.13.1 Verification Test Soil Nails ............................................................................................................ B-13 1.13.2 Proof Test Soil Nails....................................................................................................................... B-13 1.14 WALL DRAINAGE NETWORK ................................................................................................................ B-14 1.14.1 Geocomposite Drain Strips............................................................................................................. B-14 1.14.2 Footing Drains ................................................................................................................................ B-14 1.15 SHOTCRETE FACING................................................................................................................................ B-14 1.15.1 Final Face Finish ............................................................................................................................ B-14 1.15.2 Attachment of Nail Head Bearing Plate and Nut ............................................................................B-15 1.15.3 Shotcrete Facing Tolerances........................................................................................................... B-15 1.16 REINFORCING STEEL............................................................................................................................... B-15 1.17 STRUCTURAL CONCRETE ...................................................................................................................... B-15 1.18 ARCHITECTURAL SURFACE FINISHES................................................................................................ B-15 1.19 BACKFILLING BEHIND WALL FACING UPPER CANTILEVER ........................................................B-16 1.20 ACCEPTANCE ............................................................................................................................................B-16 2.0 MEASUREMENT AND PAYMENT ..........................................................................................................B-16 2.1 SOIL NAILS.................................................................................................................................................B-16 2.2 STRUCTURE EXCAVATION .................................................................................................................... B-17 2.3 WALL FACE................................................................................................................................................B-17 2.4 PAYMENT ...................................................................................................................................................B-17 2.4.1 Pay Items ........................................................................................................................................B-17 3.0 CORROSION PROTECTION......................................................................................................................B-18 REFERENCES ........................................................................................................................................................B-18

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B-3 Section xx – Soil Nail Walls PROPOSED SPECIFICATIONS PROPOSED COMMENTARY 1.1 DESCRIPTION C1.1 This work consists of constructing a permanent soil nail wall The Owner may choose to have the Contractor design and as specified herein and as shown on the Plans. The Contractor construct the work at the location shown on the drawings. The shall furnish all labor, materials, and equipment required to Contractor shall furnish all labor, plans, drawings, design complete the work. The Contractor shall select the excavation, calculations, and all other material and equipment required to drilling, and grouting methods and the diameter of the drill-holes design and construct the soil nail wall(s) in accordance with to meet the performance requirements specified herein or shown this Specification. on the Plans. Project-specific needs may require a different type of facing including reinforced shotcrete, cast-in-place concrete, and The work shall include excavating in staged lifts in accordance precast concrete panels. with the approved Contractor’s plan; detailing the drilling of the soil nail drill-holes to the diameter and length required to develop the specified resistance; grouting the soil nails; providing and installing the specified drainage features; providing and installing bearing plates, washers, nuts, and other required miscellaneous materials; and constructing the required temporary shotcrete face and constructing the final structural facing. 1.2 MATERIALS 1.2.1 Facing Facing material shall conform to the following sections and subsections. 1.2.1.1 Cast-in-place Concrete Cast-in-place (CIP) concrete shall meet the requirements of Section 5 of the AASHTO LRFD Bridge Construction Specifications. 1.2.1.2 Reinforcing Steel Reinforcing steel shall meet the requirements of Section 6 of the AASHTO LRFD Bridge Construction Specifications. 1.2.1.3 Permanent Shotcrete Permanent shotcrete shall meet the requirements of Section 24, “Pneumatically Applied Mortar,” of the AASHTO LRFD Bridge Construction Specifications. 1.2.1.4 Architectural Surface Finishes Architectural surface finishes may include textured surfaces or a surface finish with color/stain application. 1.2.2 Soil Nails 1.2.2.1 Solid Soil Nail Bar C1.2.2.1 Solid nail bars shall meet the requirements of AASHTO M Bars of A 722, Grade 1035, should not be used in 31/ASTM A 615, Grade 420 or 520, or ASTM A 722 for Grade conventional soil-nailing applications because the material 1035. Soil nail bars shall be continuous without splices or welds, tends to be more brittle and more susceptible to stress corrosion

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B-4 Section xx – Soil Nail Walls PROPOSED SPECIFICATIONS PROPOSED COMMENTARY new, straight, undamaged, bare or epoxy coated, or encapsulated than the more commonly used lower-grade steels. as shown on the Plans. Bars shall be threaded a minimum of Threading may be a continuous spiral, deformed ribbing 150 mm on the wall anchorage end, to allow proper attachment provided by the bar deformations (continuous thread bars), or of the bearing plate and nut. If threads are cut into a soil nail may be cut into a reinforcing bar. bar, provide the next larger bar number designation than what is shown on the Plans, at no additional cost. 1.2.2.2 Bar Coupler Bar couplers shall develop the full nominal tensile capacity of the soil nail bars as certified by the manufacturer. 1.2.2.3 Fusion-Bonded Epoxy Coating C1.2.2.3 Fusion-bonded epoxy coating shall meet the requirements of The coating at the wall anchorage end of epoxy-coated soil ASTM A 775 and have a minimum thickness of 0.4 mm (0.016 nail bars may be omitted over this length provided for threading in.) as applied electrostatically. Bend test requirements are the nut against the bearing plate. waived. 1.2.2.4 Encapsulation Bar encapsulation shall be a minimum 1-mm (0.04-in.) thick, corrugated, HDPE tube conforming to AASHTO M 252, or corrugated PVC tube conforming to ASTM D 1784, Class 13464-B. 1.2.3 Soil Nail Appurtenances 1.2.3.1 Centralizer Centralizers shall be manufactured from Schedule 40 PVC pipe or tube, steel, or other material not detrimental to the soil nail steel bar. Wood shall not be used. Centralizers shall be securely attached to the soil nail bar and shall be sized to allow: (a) position the soil nail bar within 25 mm (1 in.) of the center of the drill-hole; (b) tremie pipe insertion to the bottom of the drill- hole; and (c) grout to freely flow up the drill-hole. 1.2.3.2 Grout Grout shall be a neat cement or sand/cement mixture with a minimum 3-day compressive strength of 10.5 MPa (1,500 psi) and a minimum 28-day compressive strength of 21 MPa (3,000 psi), meeting the requirements of AASHTO T 106/ASTM C 109. 1.2.3.3 Fine Aggregate Fine aggregate for grout and/or shotcrete shall meet the requirements of AASHTO M 6/ASTM C 33. 1.2.3.4 Portland Cement Portland cement for grout and/or shotcrete shall meet the requirements of AASHTO M 85/ASTM C 150, Type I, II, III, or V.

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B-5 Section xx – Soil Nail Walls PROPOSED SPECIFICATIONS PROPOSED COMMENTARY 1.2.3.5 Admixtures C1.2.3.5 Admixtures shall meet the requirements of AASHTO M Admixtures that control bleed, improve flowability, reduce 194/ASTM C 494. Admixtures shall be compatible with the water content, and retard set may be used in the grout subject to grout and mixed in accordance with the manufacturer’s review and acceptance by the Engineer. Accelerators are not recommendations. permitted. Expansive admixtures may only be used in grout used for filling sealed encapsulations. 1.2.3.6 Film Protection Polyethylene film for moisture loss control shall meet the requirements of AASHTO M 171. 1.2.4 Bearing Plates, Nuts, and Head-Stud Shear Connectors 1.2.4.1 Bearing Plates C1.2.4.1 Bearing plates shall meet the requirements of AASHTO M For nominal resistance of bearing plates refer to Article 183/ASTM A 36. 5.10.9.7.2 of the AASHTO LRFD Bridge Design Specifications. 1.2.4.2 Nuts Nuts shall meet the requirements of AASHTO M 291, Grade B, hexagonal, and fitted with beveled washer or spherical seat to provide uniform bearing. 1.2.4.3 Shear Connectors C1.2.4.3 Shear connectors of the soil nail head may consist of headed- See Article 11.3.3.1 of the AASHTO LRFD Bridge studs, threaded bolts, etc. Construction Specifications. 1.2.5 Welded-Wire Mesh Welded wire mesh shall meet the requirements of AASHTO M 55/ASTM A 185 or A 497. 1.2.6 Reinforcing Steel Reinforcing steel shall meet the requirements of AASHTO M 31/ASTM A 615, Grade 420, deformed. 1.2.7 Geocomposite Sheet Drain Geocomposite sheet drain shall be manufactured with a drainage core (e.g., geonet) and a drainage geotextile attached to or encapsulating the core. Drainage core shall be manufactured from long-chain synthetic polymers composed of at least 85 percent by mass of polypropylenes, polyester, polyamine, polyvinyl chloride, polyoleofin, or polystyrene and have a minimum compressive strength of 275 kPa (40 psi) when tested in accordance with ASTM D 1621 Procedure A. The drainage core with the geotextile fully encapsulating the core shall have a minimum flow rate of 1 liter per second per meter of width tested in accordance with ASTM D 4716. The test conditions shall be under an applied load of 69 kPa (10 psi) at a gradient of 1.0 after a 100-hour seating period.

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B-6 Section xx – Soil Nail Walls PROPOSED SPECIFICATIONS PROPOSED COMMENTARY 1.2.8 Underdrain and Perforated Pipe 1.2.8.1 Pipe Underdrain and perforated pipe shall meet the requirements of ASTM 1785 Schedule 40 PVC solid and perforated wall; cell classification 12454-B or 12354-C, wall thickness SDR 35, with solvent weld or elastomeric joints. 1.2.8.2 Fittings Fittings for underdrain and perforated pipe shall meet the requirements of ASTM D 3034, Cell classification 12454-B or C, wall thickness SDR 35, with solvent or elastomeric joints. 1.2.9 Temporary Shotcrete All materials, methods, and control procedures for temporary shotcrete shall be submitted to the Owner’s Engineer for review and approval. 1.3 CONTRACTOR QUALIFICATIONS The soil-nailing contractor shall meet the following qualification require ments: 1. Completed at least three permanent soil nail wall projects during the past three years totaling at least 1,000 m2 (10,000 ft2) of soil nail wall face area and at least 500 permanent soil nails. 2. Provide a Registered Professional Engineer with experience in the construction of permanent soil nail walls on at least three completed projects over the past three years. 3. Provide on-site supervisors and drill operators with experience installing permanent soil nail walls on at least three projects over the past three years. 4. Submit a brief description of at least three projects, including the owning agency’s name, address, and current phone number; location of project; project contract value; and scheduled completion date and completion date for the project. 1.4 SUBMITTALS 1.4.1 Personnel At least 60 calendar days before starting soil nail work, submit names of the Engineer, on-site supervisors, and drill operators assigned to the project, and a summary of each individual’s experience. Only those individuals designated as meeting the qualification requirements shall be used for the project. The Contractor cannot substitute any of these individuals without written approval of the Owner or the Owner’s Engineer. The Owner’s Engineer shall approve or reject the Contractor

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B-7 Section xx – Soil Nail Walls PROPOSED SPECIFICATIONS PROPOSED COMMENTARY qualifications and staff within 15 working days after receipt of the submission. Work shall not be started nor materials ordered until the Contractor’s qualifications have been approved by the Owner’s Engineer. The Owner’s Engineer may suspend the work if the Contractor substitutes unqualified personnel for approved personnel during construction. If work is suspended due to the substitution of unqualified personnel, the Contractor shall be fully liable for all additional costs resulting from the suspension of work, and no adjustment in contract time resulting from the suspension of the work shall be allowed. 1.4.2 Surveys The Contractor shall be responsible for providing the necessary survey and alignment control during the excavation for each lift, locating drill-holes and verifying limits of the soil nail wall installation. 1.4.3 Construction Plan C1.4.3 At least 30 days before starting soil nail work, the Contractor In a performance type contract, the Contractor must select shall submit a Construction Plan to the Owner’s Engineer that one of the specialty contractors listed in the documents and includes the following. shall identify the specialty contractor on his proposal at the bid opening. No substitution will be permitted without written 1. Project start date and proposed detailed wall construction approval of the Owner’s Engineer. Substitution after the bid sequence. opening will not be grounds for changes in bid prices. 2. Drilling and grouting methods and equipment, including Under a performance type contract, the design of soil nail the drill-hole diameter proposed to achieve the specified walls shall be based on geotechnical data and project requirements provided by the Owner including but not limited nominal pullout resistance values shown on the Plans and to soil/rock nominal shear strength parameters, slope and any variation of these along the wall align ment. external surcharge loads, seismic design coefficient, type of 3. Nail grout mix design, including compressive strength wall facing, architectural treatment, corrosion protection test results (per AASHTO T 106/ASTM C 109) supplied requirements, easements, and rights-of-way. by a qualified independent testing lab verifying the specified minimum 3-day and 28-day grout compressive strengths. 4. Nail grout placement procedures and equipment. 5. Temporary shotcrete materials and methods. 6. Soil nail testing methods and equip ment setup. 7. Identification number and certified calibration records for each test jack, pressure gauge, dial gauge and load cell to be used. Jack and pressure gauge shall be calibrated as a unit. Calibration records shall include the date tested, the device identification number, and the calibration test results and shall be certified for an accuracy of at least 2 percent of the applied certification loads by a qualified independent testing laboratory within 90 days prior to submittal. 8. Manufacturer Certificates of Compliance for the soil nail ultimate strength, nail bar steel, Portland cement, centralizers, bearing plates, epoxy coating, and encapsulation 9. The Owner’s Engineer shall approve or reject the Contractor’s Construction Plan within 30 working days after the submission. Approval of the Construction Plan does not relieve the Contractor of his responsibility for the successful completion of the work.

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B-8 Section xx – Soil Nail Walls PROPOSED SPECIFICATIONS PROPOSED COMMENTARY At least 45 days before the planned start of the wall excavation, the Contractor shall submit complete design calculations and working drawings to the Owner’s Engineer for review and approval. Include all details, dimensions, quantities, ground profiles and cross-sections necessary to construct the wall. The Contractor shall verify the limits of the wall and ground survey data before preparing the drawings. The working drawings shall be prepared to the (Agency) standards. The Owner’s Engineer will approve or reject the Contractor’s submittals within 30 calendar days after the receipt of the complete submission. The Contractor shall not begin construction or incorporate materials into the work until the submittal requirements are satisfied and found acceptable to the Owner’s Engineer. 1.5 STORAGE AND HANDLING Soil nail bars shall be stored and handled in a manner to avoid damage or corrosion. Soil nail bars exhibiting abrasions, cuts, welds, weld splatter, corrosion, or pitting shall be replaced. Bars exhibiting damage to encapsulation or epoxy coating shall be repaired or replaced at no additional cost. Repaired epoxy coating areas shall have a minimum 0.3-mm (0.012-in.) thick coating. C1.6 1.6 EXCAVATION For construction on side hills, a minimum 5-m (15-ft) wide The height of exposed unsupported final excavation face cut working bench is required for adequate drill rig access. shall not exceed the vertical nail spacing plus the required Shotcrete application may be delayed up to 24 hours if the reinforcing lap or the short-term stand-up height of the ground, contractor can demonstrate that the delay will not adversely whichever is less. Excavation to the final wall excavation line affect the excavation face stability. and shotcrete application shall be completed in the same work shift, unless otherwise approved by the Owner’s Engineer. Excavation of the next-lower lift shall not proceed until soil nail installation, reinforced shotcrete placement, attachment of bearing plates and nuts, and nail testing have been completed and accepted in the current lift. Nail grout and shotcrete shall have cured for at least 72 hours or attained at least their specified 3-day compressive strength before excavating the next underlying lift.

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B-9 Section xx – Soil Nail Walls PROPOSED SPECIFICATIONS PROPOSED COMMENTARY 1.7 SOIL NAIL INSTALLATION C1.7 The soil nail length and drill-hole diameter necessary to The use of self-drilling soil nail bars (also known as hollow, develop the load capacity and to satisfy the acceptance criteria self-grouting or pressure-grouted nail bars) are not allowed for for the design load required shall be provided, but they shall be permanent construction, unless approved by the Owner. not less than the lengths or diameters shown in the Plans. Drill-holes for the soil nails shall be drilled at the locations, elevations, orientations, and lengths shown on the Plans. The drilling equipment and methods shall be selected to be suitable for the ground conditions and in accordance with the accepted installation methods submitted by the Contractor. The use of drilling mud or other fluids to remove cuttings will not be allowed. If caving ground is encountered, cased drilling methods shall be used to support the sides of the drill-holes. Soil nail bars shall be provided as shown in the Plans. Centralizers shall be provided and sized to position the soil nail bars to within 25 mm (1 in.) of the center of the drill-hole. Centralizers shall be positioned as shown on the Plans so that their maximu m center-to-center spacing does not exceed 2.5 m (8.2 ft) and shall be located to within 0.5 m (1.5 ft) from the top and bottom of the drill-hole. 1.8 GROUTING The drill-hole shall be grouted after installation of the soil nail bar and within 2 hours of completion of drilling. The grout shall be injected at the lowest point of each drill-hole through a grout tube, casing, hollow-stem auger, or drill rods. The outlet end of the conduit shall deliver grout below the surface of the grout as the conduit is withdrawn to prevent the creation of voids. The drill-hole shall be filled in one continuous operation. Cold joints in the grout column shall not be allowed except at the top of the test bond length of proof tested production nails. Grout shall be tested in accordance with AASHTO T 106/ASTM C 109 at a frequency of one test per mix design and a minimu m of one test for every 40 m3 (52 cy) of grout placed. Grout cube test results shall be provided to the Owner’s Engineer within 24 hours of testing. 1.9 SOIL NAIL TESTING 1.9.1 Tests The Contractor shall perform both verification and proof testing of designated test soil nails. Verification tests on sacrificial test nails shall be conducted at locations shown on the Plans. Proof tests on production nails shall be conducted at locations selected by the Owner’s Engineer. Testing of any nail shall not be performed until the nail grout and shotcrete facing have cured for at least 72 hours or attained at least their specified 3-day compressive strength. 1.9.2 Equipment Testing equipment shall include 2 dial gauges, dial gauge support, jack and pressure gauge, electronic load cell, and a

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B-10 Section xx – Soil Nail Walls PROPOSED SPECIFICATIONS PROPOSED COMMENTARY reaction frame. The pressure gauge shall be graduated in 500 kPa (75 psi) increments or less. Nail head movement shall be measured with a minimum of 2 dial gauges capable of measuring to 0.025 mm (0.001 in.). 1.10 VERIFICATION TESTING Verification testing shall be conducted prior to installation of production soil nails on sacrificial soil nails to confirm the appropriateness of the Contractor’s drilling and installation methods, and verify the required nail pullout resistance. C1.10.1 1.10.1 Methods At least two verification tests should be conducted in each The verification tests must be conducted on nails of the same soil strata in which it is anticipated that nail bond zone will be design and constructed with the same construction methods to be grouted. used on production nails for meaningful results. Where possible, verification tests should be conducted to Verification test nails shall have both bonded and unbonded failure to establish a maximum resistance with respect to lengths. The nail bar shall not be grouted along the unbonded pullout. length. The unbonded length of the test nails shall be at least 1 m (3 ft). The bonded length of the soil nail during verification tests, LB VT, shall be the smaller value of the following range: The maximum length for verification tests, LB VT max, is 3 m (10 ft) LB VT = greater of selected so that the nail load does not exceed 90 percent of LB VT max factored nominal tensile resistance of the soil nail bar during the verification test. The maxi mum length, LB VT max, is defined as: C RT × At × f Y × φT −VT LB VT max = rPO × φPO where: CRT = reduction coefficient; At = cross-sectional area of soil nail bar; Use CRT = 0.9 for 420 and 520 MPa (Grade 60 and 75) bars. fY = nominal yield resistance of soil nail bar; If 1,035 MPa (Grade 150) soil nail bars are allowed in the job, rPO = nominal pullout resistance (per unit length) of use CRT = 0.8. soil nail, as specified herein or in Plans; φT-VT = resistance factor for soil nail in tension in In verifications tests, select φT-VT = 0.4 or, preferably, 0.33. verification tests; and Select φPO based on Table 11.5.6-1, “Resistance Factors,” of φPO = resistance factor for soil nail pullout. AAHTO LRFD Bridge Design Specifications. For preliminary values, use φPO = 0.5. The maximum bonded length shall be preferably based on The selection of φT-VT during verification tests should be production nail maximum bar grade. Larger bar sizes shall be provided at no additional cost, if required, to meet the 3-m (10- consistent with the maximu m test load that has been selected ft) minimum test bonded length require ment. for the verification test. The maximu m load depends on the selected φPO and must be selected such that the test bars are not The Design Load during the verification test, DL, shall be overstressed during the test. calculated based on as-built bonded lengths, as follows: DL = LB VT × rPO ×φPO 1.10.2 Schedule C1.10.2 Verification tests shall be conducted by incrementally loading the verification test nails to failure or a maximum test load of

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B-11 Section xx – Soil Nail Walls PROPOSED SPECIFICATIONS PROPOSED COMMENTARY 200 percent of the DL in accordance with the following loading schedule. The Contractor shall record soil nail movements at each load increment. In soils that are susceptible to creep, extended creep tests beyond the tests required by these specifications should be Verification Test Loading Schedule conducted based on PTI (2005) methods. The alignment load, Load Hold Time AL, should be the minimum load required to align the testing 0.05 DL max. apparatus and should not exceed 5 percent of the DL. 1 minute (= alignment load, AL) 0.25 DL 10 minutes In projects, for which there is no local experience in soil nailing or the degree of uncertainty in the pre-selected nominal 0.50 DL 10 minutes pullout resistance (per unit length) values is significant, the 0.75 DL 10 minutes Owner or the Owner’s Engineer may require the Contractor to 1.00 DL 10 minutes perform verification tests up to a maximum test load of 300 1.25 DL 10 minutes percent of the DL in the tests. For these situations, the loading 1.50 DL (Creep Test) 60 minutes shall be performed according to the schedule below: 1.75 DL 10 minutes 2.00 DL 10 minutes Additional Verification Test Loading Schedule 1 minute (record 0.05 DL max. (AL) Load Hold Time permanent set) From AL to 2.00 DL (or as shown Load levels beyond 200 percent of DL are optional. Failure) previously Dial gauges shall be set to “zero” after the alignment load has 2.50 DL (optional) 10 minutes been applied. Following application of the maximum load (3.0 × 3.0 DL (optional) 10 minutes DL), the load shall be reduced to the alignment load (0.05 × DL 1 minute (record maximum) and the permanent set shall be recorded. 0.05 DL max. (AL) permanent set) Each load increment shall be held for at least 10 minutes. The verification test nail shall be monitored for creep at the 1.50 × DL load increment. Nail movements shall be measured and recorded during the creep portion of the test in increments of 1, 2, 3, 5, 6, 10, 20, 30, 50, and 60 minute(s). The load shall be maintained during the creep test to within 2 percent of the intended load by use of a load cell. 1.11 PROOF TESTING C1.11 Successful proof testing shall be demonstrated on at least 5 percent of production soil nails in each nail row or a minimum of one per row. The Owner’s Engineer shall determine the locations and number of proof tests prior to nail installation in each row. C1.11.1 1.11.1 Methods The unbonded length is temporary because this length is Production proof test nails shall have both bonded and grouted after the proof test is completed. temporary unbonded lengths. The unbonded length of the test nail shall be at least 1 m (3 ft). The bonded length of the soil nail during proof production tests, LB PT, shall be at least 3 m (10 ft) but not longer than a maximum length, LB PT max. The maximum length for proof tests, LB PT max, is selected so Therefore, the following requirements shall be met: that the nail load does not exceed 90 percent of factored nominal tensile resistance of the soil nail bar during the proof test. 3 m (10 ft) LB PT = greater of LB PT max

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B-12 Section xx – Soil Nail Walls PROPOSED SPECIFICATIONS PROPOSED COMMENTARY The maxi mum length LB PT max is defined as: C RT × At × f Y × φT − PT LB PT max = rPO × φPO where: Use CRT = 0.9 for 420 and 520 MPa (Grade 60 and 75) bars. If 1,035 MPa (Grade 150) soil nail bars are allowed in the job, CRT = reduction coefficient; use CRT = 0.8. At = cross-sectional area of soil nail bar; In proof tests, select φT-PT = 0.67. Select φPO based on Table fY = nominal yield resistance of soil nail bar; rPO = nominal pullout resistance (per unit length) of 11.5.6-1, “Resistance Factors,” of AAHTO LRFD Bridge soil nail, as specified herein or in Plans; Design Specifications. For preliminary values, use φPO = 0.5. φT-PT = resistance factor for soil nail in tension in proof tests; and The selection of φT-PT during proof tests should be consistent φPO = resistance factor for soil nail pullout. with the maximum test load that has been selected for these tests. The maximum load depends on the selected φPO and must be selected such that the test bars are not overstressed during The Design Load during the verification test, DL, shall be the test. This is usually 1.5 DTL. Avoiding bar overstressing calculated based on as-built bonded lengths, as follows: during the test allows using the test bars as production bars after the test. LB PT × rPO ×φPO DL = Production proof test nails shorter than 4 m (12 ft) may be constructed with less than the minimum 3-m (10-ft) bond length. 1.11.2 Schedule C1.11.2 Proof tests shall be conducted by incrementally loading the The alignment load, AL, should be the minimum load proof test nail to 150 percent of DL in accordance with the required to align the testing apparatus and should not exceed 5 following loading schedule. Soil nail movements shall be percent of the DL. recorded at each load increment. Proof Test Loading Schedule Load Hold Time 0.05 DL max. (AL) Until Movement Stabilizes 0.25 DL Until Movement Stabilizes 0.50 DL Until Movement Stabilizes 0.75 DL Until Movement Stabilizes 1.00 DL Until Movement Stabilizes 1.25 DL Until Movement Stabilizes 1.50 DL (Max. Test Load) Creep Test (see below) Dial gauges shall be set to “zero” after the alignment load has been applied. The creep period shall start as soon as the maximum test load (1.50 × DL) is applied and the nail movement shall be measured and recorded at 1, 2, 3, 5, 6, and 10 minute(s). Where the nail movement between 1 minute and 10 minutes exceeds 1 mm (0.04 in.), the maximum test load shall be maintained for an additional 50 minutes and nail movements shall be recorded at 20, 30, 50, and 60 minutes. All load increments shall be maintained to within 5 percent of the intended load.

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B-13 Section xx – Soil Nail Walls PROPOSED SPECIFICATIONS PROPOSED COMMENTARY 1.12 ACCEPTANCE CRITERIA OF TEST SOIL NAILS A test nail shall be considered acceptable when all of the following criteria are met: 1. For verification tests, the total creep movement is less than 2 mm (0.08 in.) between the 6- and 60-minute readings, and the creep rate is linear or decreasing throughout the creep test load hold period. 2. For proof tests, the total creep movement is less than 1 mm (0.04 in.) during the 10-minute readings or the total creep movement is less than 2 mm (0.08 in.) during the 60-minute readings, and the creep rate is linear or decreasing throughout the creep test load hold period. 3. For verification and proof tests, the total measured movement at the maximu m test load exceeds 80 percent of the theoretical elastic elongation of the unbonded length of the test nail. A pullout limit state does not occur at 2.0 × DL under 4. verification testing and 1.5 × DL test load under proof testing. Pullout limit state is defined at a load level at which the test load cannot be further increased while there is continued pullout movement of the test nail. The load at the pullout limit state shall be recorded as part of the test data. 5. Maintaining stability of the temporary unbonded test length for subsequent grouting is the Contractor’s responsibility. If the unbonded test length of production proof test nails cannot be satisfactorily grouted after testing; the proof test nail shall become sacrificial and shall be replaced with an additional production nail installed at no additional cost to the Owner. 1.13 REJECTION OF TEST SOIL NAILS 1.13.1 Verification Test Soil Nails The Owner’s Engineer will evaluate the results of each verification test. Installation methods that do not satisfy the nail testing requirements shall be rejected. The Contractor shall propose alternative methods for review by the Owner’s Engineer and shall install replacement verification test nails. Replacement test nails shall be installed and tested at no additional cost. 1.13.2 Proof Test Soil Nails For proof test nails, the Owner’s Engineer may require the Contractor to replace some or all of the installed production nails between a failed proof test soil nail and the adjacent passing proof test nail. Alternatively, the Owner’s Engineer may require

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B-14 Section xx – Soil Nail Walls PROPOSED SPECIFICATIONS PROPOSED COMMENTARY the installation and testing of additional proof test nails to verify that adjacent previously installed production nails have sufficient nominal pullout resistance. Installation and testing of additional proof test nails or installation of additional or modified nails as a result of proof test nail failure(s) shall be at no additional cost. 1.14 WALL DRAINAGE NETWORK All elements of the soil nail wall drainage network shall be installed and secured as shown on the Plans. The drainage network shall consist of geocomposite drain strips, PVC connection pipes, soil nail wall footing drains, and weepholes, as shown on the Plans. Exclusive of the wall footing drains, all elements of the drainage network shall be installed prior to shotcreting. 1.14.1 Geocomposite Drain Strips Geocomposite drain strips shall be centered between the columns of soil nails, as shown on the Plans. Drain strips shall be at least 300 mm (12 in.) wide and placed with the geotextile side against the ground. Strips shall be secured to the excavation face. Contamination of the geotextile with shotcrete shall be prevented. Drain strips shall be vertically continuous. Splices shall be made with a 300 mm (12 in.) minimum overlap such that the flow of water is not impeded. Drain plate and connector pipe shall be installed at the base of each strip. Damage to the geocomposite drain strip shall be repaired so that water flow is not interrupted. 1.14.2 Footing Drains Footing drains shall be installed at the bottom of the wall, as shown on the Plans. The drainage geotextile shall envelope the footing drain aggregate and pipe and shall conform to the dimensions of the trench. The drainage geotextile shall overlap on top of the drainage aggregate as shown on the Plans. Damaged or defective drainage geotextile shall be repaired or replaced. 1.15 SHOTCRETE FACING Shotcrete facing and permanent shotcrete facing shall be provided as required. Where shotcrete is used to complete the top ungrouted zone of the soil nail drill-hole near the face, the nozzle shall be positioned into the mouth of the drill-hole to completely fill the void. 1.15.1 Final Face Finish Shotcrete finish shall be either an undisturbed gun finish as applied from the nozzle or a rod, broom, wood float, rubber float, steel trowel, or rough screeded finish as shown on the Plans.

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B-15 Section xx – Soil Nail Walls PROPOSED SPECIFICATIONS PROPOSED COMMENTARY 1.15.2 Attachment of Nail Head Bearing Plate and Nut A bearing plate, washers, and nut shall be attached to each nail head as shown on the Plans. While the shotcrete construction facing is still plastic and before its initial set, the plate shall be uniformly seated on the shotcrete by hand-wrench tightening the nut. Where uniform contact between the plate and the shotcrete cannot be provided, the plate shall be set in a bed of grout. After grout has set for 24 hours, hand-wrench tighten the nut. The bearing plates with headed studs shall be located within the tolerances shown on the Plans. 1.15.3 Shotcrete Facing Tolerances Construction tolerances for the shotcrete facing from plan location and plan dimensions shall be as follows: Horizontal location of welded wire mesh; reinforcing bars, and headed studs: 10 mm (0.4 in.) Location of headed-studs on bearing plate: 6 mm (1/4 in.) Spacing between reinforcing bars: 25 mm (1 in.) Reinforcing lap: 25mm (1 in.) Complete thickness of shotcrete: • If troweled or screeded: 15 mm (0.6 in.) • If left as shot: 30 mm (1.2 in.) Planeness of finish face surface-gap under 3-m (10-ft) straightedge: • If troweled or screeded: 15 mm (0.6 in.) • If left as shot: 30 mm (1.2 in.) Nail head bearing plate deviation from parallel to wall face: 10 degrees 1.16 REINFORCING STEEL The Contractor shall su bmit all order lists and reinforcement bending diagrams to the Owner’s Engineer and shall fabricate reinforcing steel; ship and protect material; and place, fasten, and splice reinforcing steel as required by the Plans. 1.17 STRUCTURAL CONCRETE The Contractor shall design the concrete mix; store, handle, batch, and mix material and deliver concrete; provide quality control; and construct concrete facing. 1.18 ARCHITECTURAL SURFACE FINISHES Textured form liners shall be furnished, form liners installed, and a surface finish (color/stain application) applied that will duplicate the architectural surface finish shown on the Plans.

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B-16 Section xx – Soil Nail Walls PROPOSED SPECIFICATIONS PROPOSED COMMENTARY The Contractor shall submit detailed drawings of the form liner for approval by the Owner’s Engineer at least 7 days before form liner work begins. Before production work begins, a 1-m (3-ft) high by 0.5-m (1.5-ft) wide by 3-m (10-ft) long test panel shall be constructed on site using the same forming methods, procedures, form liner, texture configuration, expansion joint, concrete mixture and color/stain application proposed for the production work. 1.19 BACKFILLING BEHIND WALL FACING UPPER CANTILEVER If backfilling is required behind an extension of the wall facing at the top of a soil nail wall, compaction of the soil backfill within 1 m (3 ft) shall be limited to light mechanical tampers. Backfill shall be relatively free-draining granular soil meeting the requirement of Article 7.3.5 (of the AASHTO LRFD Bridge Construction Specifications). 1.20 ACCEPTANCE Material for soil nail retaining walls will be accepted based on the manufacturer production certification or from production records. Construction of soil nail retaining walls will be accepted based on visual inspection and the examination of relevant production testing records by the Owner’s Engineer. 2.0 MEASUREMENT AND PAYMENT 2.1 SOIL NAILS Production soil nails shall be measured by the linear meter (or foot). The length to be paid will be the length measured along the soil nail bar centerline from the back face of shotcrete to the bottom tip end of the nail bar as shown on the Plans. No separate measurement will be made for proof test nails, which shall be considered incidental to production nail installation. Verification test nails shall be measured by each test meeting the acceptance criteria of Article 1.10. Failed verification test nails or additional verification test nails installed to verify alternative nail installation methods proposed by the Contractor will not be measured.

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B-17 Section xx – Soil Nail Walls PROPOSED SPECIFICATIONS PROPOSED COMMENTARY 2.2 STRUCTURE EXCAVATION Structure excavation for the soil nail wall shall be measured as the theoretical plan volume in cubic meters (cubic feet) within the structure excavation limits shown on the Plans. This will be the excavation volume within the zone measured from top to bottom of shotcrete wall facing and extending out 2 m (6 ft) horizontally in front of the plan wall final excavation line. Additional excavation beyond the Plan wall final excavation line resulting from irregularities in the cut face, excavation overbreak or inadvertent excavation will not be measured. No measurement will be made for using temporary stabilizing berms. General roadway excavation, including hauling, will not be a separate wall pay item but will be measured and paid as part of the general roadway excavation. 2.3 WALL FACE The wall face of soil nail walls shall be measured by the square meter (square foot) of wall face. Measurement will be made on the vertical plane of front face accepted in the final work. No measurement or payment will be made for additional shotcrete or CIP concrete needed to fill voids created by irregularities in the cut face, excavation overbreak or inadvertent excavation beyond the Plan final wall face excavation line, or failure to construct the facing to the specified line and grade and tolerances. The final pay quantity shall include all structural shotcrete, admixtures, reinforcement, welded wire mesh, wire holding devices, wall drainage materials, bearing plates and nuts, test panels and all sampling, testing and reporting required by the Plans and this Specification. The final pay quantity shall be the design quantity increased or decreased by any changes authorized by the Owner’s Engineer. 2.4 PAYMENT C2.4 The accepted quantities, measured as provided in Articles 2.1, Under a performance type contract, payment may be made on 2.2 and 2.3, will be paid for at the contract unit price per unit of a lump-sum basis to include all materials, labor and design measurement for the pay items listed below that are shown on costs. the bid schedule. Payment will be full compensation for the work prescribed in this section. Payment will be made under: 2.4.1 Pay Items Pay Unit Pay Item Permanent Soil Nails. No. _ Bar (Grade _) Linear meter (or linear foot) Verification Test Nails Each Structure Excavation-Soil Nail Wall Cubic meter (or cubic foot) Soil Nail Wall Square meter (or square foot)

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B-18 Section xx – Soil Nail Walls PROPOSED SPECIFICATIONS PROPOSED COMMENTARY 3 CORROSION PROTECTION C3 Soil nails and soil nail head components shall be protected Corrosion protection shall be applied in accordance with the against corrosion consistent with the ground and groundwater provisions of AASHTO LRFD Bridge Construction conditions at the site. The level and extent of corrosion Specifications, Section 6, “Ground Anchors.” protection shall be a function of the ground environment and the potential consequences of a soil nail failure. A full discussion on corrosion of metallic components and a methodology that assists in selecting the appropriate level of corrosion protection of soil nail walls is presented in Lazarte et al. (2003). REFERENCES Lazarte, C.A., V. Elias, R.D. Espinoza, and P.J. Sabatini (2003). “Soil Nail Walls,” Geothechnical Engineering Circular No. 7, FHWAO-IF-03-017, Federal Highway Administration, Washington, D.C., 305p. PTI (2005). “Recommendations for Prestressed Rock and Soil Anchors,” 4th ed. Post-Tensioning Institute, Phoenix, Arizona.