Part 1 — General
1.1 Section Includes
A.Permanent soil nail retaining walls , including design .
B.Monitoring and control of deformations of the soil nail wall, surrounding ground, utilities, and other facilities existing at the time of construction.
C.Verification and proof tests including load schedules, acceptance criteria, frequency of tests, and testing equipment.
1.2 Related Sections
A.Section 02056 : Embankment, Borrow, and Backfill
B.Section 02075 : Geotextiles
C.Section 02317 : Structural Excavation and Backfill
D.Section 02342 : Shotcrete
E.Section 03055: Portland Cement Concrete
F.Section 03152
G.Section 03211: Reinforcing Steel
H.Section 05120: Structural Steel
1.3 References
A.AASHTO M 31: Deformed and Plain Billet -Steel Bars for Concrete Reinforcement
B.AASHTO M 85: Portland Cement
C.AASHTO M 252: Corrugated Polyethylene Drainage Pipe
D.AASHTO M 270: Carbon and High Strength Low Alloy Structural Steel, Shapes, Plates and Bars and Quenched and Tempered Alloy Structural Steel Plates for Bridges
E.AASHTO M 291: Carbon and Alloy Steel Nuts
F.AASHTO T 106: Compressive Strength of Hydraulic Cement Mortar
G.AASHTO T 244: Mechanical Testing of Steel Products
H.ASTM A 519 : Seamless Carbon and Alloy Steel Mechanical Tubing
I.ASTM A 767: Zinc-Coated (Galvanized) Bars for Concrete Reinforcement
J.ASTM A 775: Standard Specification for Epoxy -Coated Steel Reinforcing Bars
K.ASTM C 33: Concrete Aggregates
L.ASTM C 109: Compressive Strength of Hydraulic Cement Mortars
M.ASTM D 1621: Compressive Properties of Rigid Cellular Plastics
N.ASTM D 1785: Poly(Vinyl Chloride) (PVC) Plastic Pipe, Schedules 40, 80, and 120
O.ASTM D 3034: Type PSM Poly(Vinyl Chloride) (PVC) Sewer Pipe and Fittings
P.ASTM D 4380: Density of Bentonitic Slurries
Q.ASTM D 4716: Determining the (In- plane) Flow Rate per Unit Width and Hydraulic Transmissivity of a Geosynthetic Using a Constant Head
R.FHWA Geotechnical Engineering Circular No. 7: Soil Nail Walls Reference Manual, Report No. FHWA -NHI-14-007, February 2015 (FHWA GEC7)
1.4 Definitions
A.Bird’s Beak: The space above the bottom elevation of the inclined drill hole opening at the face of the wall after grout placement.
B.Hollow Bar Soil Nail (HBSN): Hollow core and self -drilling bar advanced into the soil by drilling with a sacrificial bit as grout is injected through the bar.
1.5 Submittals
A.Soil Nail Contractor Qualifications for review . Include at least the following:
1.Company name.
2.List of at least three projects in the last five years demonstrating successful construction of permanent soil nail retaining walls totaling at least 10,000 ft 2 of wall face area and at least 500 permanent soil nails. Include the following for each project:
a.Project name and location.
b.Owner or agent references and their contact information (phone and email) . 1) Satisfactory references are those responsible for oversight or inspection of the project.
c.A brief description of the scope of work and approximate date of the project completion.
3.List of planned subcontractors for design and construction.
4.List of the following personnel and their experience with at least three permanently anchored or nailed structures in the last three years :
a.Drill operators
b.On-site supervisors assigned to the project.
5.Do not substitute for these personnel without a uthorization .
B.Wall Designer Qualifications for review when Contractor provides wall design . Include at least the following:
1.Wall Designer name and professional engineer licensing information.
2.Company name.
3.List of at least three projects in the last five years demonstrating successful construction of permanent soil nail retaining walls. Include the following for each project:
a.Project name and location.
b.Owner or agent references and their contact information (phone and email) . 1) Satisfactory references are those responsible for oversight of the project.
c.A brief description of the scope of work and approximate date of the project completion.
4.Do not substitute for the wall designer without authorization.
C.Soil Nail Retaining Wall Drawings for review. Includ e at least the following:
1.Plans, profiles, cross -sections, quantities, and details for each retaining wall.
a.Subsurface exploration locations noted with station and offsets with respect to the wall alignment. 1) Provide soil data sheets for each subsurface exploration.
b.Top of wall detail . 1) Aesthetically pleasing 2) Adequately s upports fence, drainage, or other requirements as shown.
c.Production s oil nail details showing at least the following: 1) Bar sizes and grades 2) Corrosion protection 3) Centralizers 4) Nail head assemblies
d.Verification test nail locations
e.Test nail detail s (verification and proof) including nail size, bonded/unbonded lengths, reaction frames and supports, jacks, load cells, and gauges .
f.Provisions for facilities directly behind the wall face, such as foundation elements, utilities, piping, and guardrail posts .
g.Surface and subsurface drainage details.
h.Architectural treatment details for wall facing elements and concrete color as shown.
i.Expansion/contraction joint locations and details.
j.Structure number details
2.Include supporting calculations sufficient to demonstrate that the soil nail walls are designed according to the required criteria.
3.Provide the seal of a Professional Engineer (PE) or Professional Structural Engineer (SE) licensed in the State of Utah on the drawings and calculations.
D.Construction Plan for review . Include at least the following:
1.Wall construction start date and proposed detailed wall construction sequence and phasing plan.
2.Proposed methods to contain grout, shotcrete, and void- filling materials within the project area and the Department Right -of-Way.
3.Proposed drilling methods, equipment, and drill hole diameters.
4.Proposed methods of soil nail installation.
5.Procedures for placing nail grout, grout quality control plan, and equipment.
6.Proposed methods for controlling seepage and unstable drill holes.
7.Monitoring and instrumentation plan. Include at least the following:
a.Measures to verify wall and slope stability during construction
b.Details for measuring the movement of the excavated face and the wall during stability testing and construction
c.Methods , frequencies , and locations of measurement points for monitoring displacements of the wall facing, surrounding ground, utilities, and other existing facilities
E.Equipment calibration data for information :
1.Calibration data for testing equipment including load cells, test jacks, pressure gages, and grout pumps
a.Include calibration date, device identification number, and calibration results, certified with an accuracy of at least 2 percent of the applied certification.
F.Manufacturer’s product data sheets and installation instructions for furnished materials , for information, such as the following:
1.Soil nail bar s
a.Include ultimate strength and yield strength
b.Include corrosion protection, such as epoxy coating or encapsulation.
2.Bar couplers
3.Geocomposite strip drains
4.Centralizers
5.Drain connection grates
G.Nail grout mix design for approval , including:
1.Compressive strength test results, according to AASHTO T 106 or ASTM C 109, supplied by a qualified independent testing lab and verifying specified 3 day and 28 day minimum grout compressive strengths.
2.Include specific gravity test results of the fresh grout used for compress ion testing for neat cement grout .
H.Soil Nail Test Results for information within 48 hours of the test.
1.Include results from failed and passing soil nails.
2.Include at least the following:
a.Project name, location , and type (verification or proof) of test. 1) Include times and date s of drilling, installation, grouting, and testing.
b.Name of person(s) performing testing.
c.Hydraulic jack calibration information.
d.Soil nail bar bonded and unbonded lengths, as well as any additional bar len gth used for testing.
e.Soil nail bar type , diameter, cross- sectional area, and grade of steel.
f.Drill method, hole length, and diameter.
g.Maximum test load.
h.Ultimate load capacity of soil nail bar .
i.Soil to grout bond strength.
j.Tabulated individual and average displacements for each dial gage at each specified loading increment and observation period.
I.Soil Nail Retaining Wall As -Built Drawings for information within 30 days after completion of the work.
1.Provide the locations and lengths of the nails for each wall. Include Northings, Eastings, elevation, azimuth, and inclination (to the nearest 0.1 inch and 0.5 degrees), Include survey datum.
2.Provide revised design calculations signed and sealed by a PE or SE licensed in the State of Utah for design changes made during the construction of the wall.
1.6 Aesthetic S Test Panels
A.Construct a 3 ft high by 10 ft long test panel on- site for final shotcrete facings with sculpted or formed aesthetic treatments .
1.Receive authorization before beginning production work .
2.Use the same sculpting or forming methods, procedures, form liner, texture configuration, expansion joint, concrete mixture, and color/stain application proposed for the production work.
3.Furnish one test panel for each type of wall finish.
1.7 Quality Control
A.Soil Nail Grout
1.Test each batch of grout for specific gravity using a mud balance according to the procedure in ASTM D 4380.
1.8 Delivery, Storage and Handling
A.Deliver, store and handle materials in a manner that will prevent contamination, segregation, corrosion, and damage.
1.Store and protect all bars such that corrosion protective coatings, bar surfaces, and threads are undamaged.
2.Geocomposite strip drain
a.Store/stockpile in a manner which protects the material from mud, dirt, dust, debris, and shotcrete rebound.
b.Do not remove the protective wrapping until immediately before material is installed.
c.Avoid exposure to ultraviolet light.
Part 2 — Products
2.1 Soil Nails
A.Soil Nail Tendon .
1.Provide fully threaded solid or hollow bars as shown, continuous or with coupl ers, threaded to allow proper attachment of bearing plate, washer, and nut.
2.Solid Bar Soil Nails (SBSNs)
a.Use sol id threaded bar according to one of the following: 1) AASHTO M 31 Grade 75 or 80 2) AASHTO M 275 Grade 150 .
b.Verify that bar meets the minimum capacity required at the threaded section if threads are cut into the bar.
3.Hollow Bar Soil Nails (HBSNs) , unless excluded as shown.
a.ASTM A 519 Grade 75 or better, size as shown .
b.Fully -threaded hollow -steel tubing that serves as drilling steel, grout transfer medium, and reinforcing element of the soil nail.
c.Uniform elongation without necking ( A gt) greater than or equal to 5 percent.
d.Minimum Charpy impact resistance of 30 ft -lb at - 4 degrees F (40 J at - 20 degrees C) according to AASHTO T 244.
e.Provide bar couplers with seal s or similar mechanism to verify minimum grout loss and a means of transferring percussive drilling forces, if required.
f.Select drill bits based on subsurface data and minimum grout column requirements, with at least two ports for grout exit.
4.Bar Couplers
a.Develop the full nominal tensile capacity of the soil nail bar as certified by the manufacturer.
5.Corrosion protection
a.SBSN s 1) Bar e ncapsulation . Use one of the following sheathings: a) Corrugated high- density polyethylene (HDPE) tube having a minimum wall thickness of 60 mils and conforming to AASHTO M 252. b) Corrugated PVC tube having a minimum wall thickness of 40 mils. 2) Bar coating. Use one of the following: a) Use epoxy -coated bars according to ASTM A 775 with between 0.008 and 0.012 inch coating thickness. Omit bend test requirements. b) Use galvanized bars according to ASTM A 767 with minimum coating thickness of 3.4 mil.
B.Centralizers
1.SBSNs .
a.Use centralizers manufactured from Schedule 20 or 40 PVC pipe securely attached to the soil nail bar with coated wire.
b.Size to position the soil nail bar within 1.0 inch of the center of the drill hole .
2.HBSNs.
a.Use steel centralizers that do not obstruct the flow of grout, drilling fluids, and spoils .
C.Nail Head Assemblies
1.Bearing Plate Assembly
a.Bearing Plate 1) AASHTO M 270, Grade 36. Refer to Section 05120.
b.Shear Connectors 1) Headed studs or anchor bolts
c.Fabrication 1) Refer to AASHTO/AWS D1.5.
d.Galvanize after fabrication according to ASTM A 767 .
2.Nuts and Washers
a.AASHTO M 291, Grade B, hexagonal .
b.Fit with beveled washers or spherical seats to provide uniform bearing.
c.Galvanize according to ASTM A 767 .
D.Soil Nail Grout
1.Use a neat cement or sand/cement mixture
a.Use Type II Portland Cement meeting AASHTO M 85.
b.Use sand for grout and meeting requirements of ASTM C 33 for SBSNs .
c.Do not use sand in the nail grout mix for HBSNs .
d.Use a dmixtures as appropriate to control bleed, improve flowability, reduce water content, and/or retard set , as specified in the authorized submittals. 1) Use only admixtures that are compatible with the grout and mixed according to the manufacturer’s recommendations. 2) Do not use accelerators.
2.Meet 3 day minimum compressive strength of at least 2,000 psi according to AASHTO T 106
3.Meet 28 day minimum compressive strength of at least 4,000 psi according to AASHTO T 106
4.Meet specific gravity between 1.80 and 1.90.
2.2 Facing
A.Shotcrete
1.Refer to Section 02342.
B.Concrete
1.Class AA(AE). Refer to Section 03055.
C.Reinforcing Steel and Welded Wire Reinforcement
1.Coated. Refer to Section 03211.
2.4 Geocomposite Strip Drain
A.Use a strip drain consisting of a drainage core and an attached or encapsulating filtration geotextile meeting the following:
1.At least 85 percent by mass of polypropylenes, polyester, polyamine, polyvinyl chloride, polyolefin, or polystyrene.
2.Compressive strength of at least 40 psi when tested according to ASTM D 1621, Procedure A.
3.Flow rate of at least 0.1 gallons per second per foot of strip width under a gradient of 1.0 tested according to ASTM D 4716.
4.Provide in rolls wrapped with a protective covering and labeled to identify the production run.
2.5 Toe Drain
A.Perforated Pipe
1.ASTM D 1785 Schedule 40 PVC solid and perforated wall; cell classification 12454- B or 12454- C, wall thickness SDR 35, with solvent or elastomeric joints
B.Fittings
1.ASTM D 3034, cell classification 12454- B or 12454- C, wall thickness SDR -35, with solvent or elastomeric joints.
C.Free-Draining Granular Backfill
1.Refer to Section 02056.
D.Drainage Geotextile
1.Refer to Section 02075.
2.6 Expansion Joint Materials
A.Preformed Joint Filler
1.Refer to Section 03152.
B.Backer Rod
1.Refer to Section 03152
C.Joint Sealant
1.Use Joint Sealer (Structures). Refer to 03152.
2.7 Equipment
A.Soil Nail Grouting
1.Use a high- shear colloidal mixer with separate holding tank and water and cement dosing system to verify continuous grouting independent from mixing.
2.Capable of grout pump flow rate of at least 15 gpm for bars less than 2 inch diameter and 45 gpm for bars 2 inch or greater in diameter.
3.Capable of grout pump pressure of at least 250 psi in sands/gravels and 1,500 psi in clays/silts.
B.Soil Nail Testing
1.Provide testing equipment including dial gages, dial gage support, jack and pressure gage, load cell, and a reaction frame as shown.
a.Use a pressure gage with a maximum graduation of 50 psi and use calibrated load cell for load steps.
b.Support dial gages on a frame that is independent from the jacking and the wall.
c.Measure nail head movement with at least 2 dial gages capable of measuring to 0.001 inch
2.Use testing equipment that has been calibrated by an independent testing lab within 90 days of the submittal date.
a.Calibrate jack and pressure gage as a single unit.
2.8 Soil Nail Wall Design Requirements
A.Design the soil nail walls according to the GMOI and AASHTO LRFD Bridge Design Specification except where modified in this Section and as shown. Refer to FHWA GEC 7 for design guidance not covered by AASHTO LRFD (e.g. , HBSNs).
1.Provide a minimum design life of 75 years for soil nail walls and all components, and include supporting data and calculations in the design submittal.
2.Provide corrosion protection as shown for SBSNs .
3.Provide sacrificial steel corrosion protection according to FHWA GEC 7 for HBSNs .
4.Do not use HBSNs in aggressive soils.
5.Use a soil nail length of at least 10 ft.
6.Design soil nail walls to withstand seismic ground shaking as shown.
B.Provide a structural facing thickness of at least 10 inches excluding architectural relief.
1.Provide reinforcement in the structural facing consisting of at least No. 4 bars at 12 inch spacing in both directions.
a.Supplement this minimum reinforcing with additional bars or with wire mesh as required by the design and construction methods.
C.Extend facing at the toe of the wall to at least 2 ft below the finished grade at front face of wall at all points .
D.Provide expansion joints and contraction joints at appropriate intervals for the wall design , according to FHWA GEC 7 .
E.Locate the top row of nails within 2 ft of the top of the wall.
F.Arrange soil nails so that the distance between the lowest row of soil nails and the facing at the toe of the wall is less than two thirds of the vertical nail spacing.
G.Consider the locations of existing utilities or obstructions in the area of construction.
H.Use a design batter of at least 2 degrees for the final soil nail wall facing.
I.Provide backwall drainage through weep holes or to toe drain, as shown.
1.Transmit backwall drainage between every column of soil nails down the wall through geocomposite strip drains .
2.Provide a weep hole for each geocomposite strip drain.
3.Provide a positive connection from each strip drain to a toe drain (where used), using a compatible drain connection grate and pipe.
J.Include provisions to prevent water flow over the top surface of the walls.
K.Show the quantity and locations of verification tests to be performed, accounting for subsurface conditions and variability, wall geometry, and project phasing.
1.Require at least two verification tests per wall.
2.Size verification test nail s so that the maximum test load does not exceed 90 percent of the minimum yield strength for Grade 75 through 80 bars and 80 percent of the minimum ultimate tensile strength for Grade 150 bars.
Part 3 — Execution
3.1 General
A.Follow the authorized soil nail retaining wall drawings.
B.Perform additional exploration and testing when appropriate to complete final design.
3.2 EXCAVATION A. Refer to Section 02317.
B.Establish the ground contour above the wall to its final configuration and slope as shown before beginning excavation of the soil for the first row of soil nails.
C.Excavate from top down in staged horizontal lifts.
1.Limit the excavation to no more than 3 ft below the elevation at which the soil nails will be installed for the current lift.
2.Place reinforced initial shotcrete facing before the vertical cut becomes unstable , but no more than 24 hours after excavation.
a.Place reinforcement with at least 2 inch of shotcrete cover between the soil or the strip drain, and the reinforcement.
3.Do not excavate a lift until the soil nail installation and reinforced initial shotcrete placement for the preceding lift is completed.
D.Excavated face
1.Remove loose materials, mud, rebound, and other foreign matter that could prevent or reduce shotcrete bond before placing shotcrete.
2.Accuracy
a.Sufficient to a llow placement of the required shotcrete thickness shown. 1) Additional shotcrete thickness due to overexcavation or irregularities in the excavated face is at no additional cost to the Department.
b.Sufficient to prevent damage to overlying shotcrete sections by undermining or other causes.
E.Monitor the wall and slope stability during construction.
1.Suspend soil nail wall construction if an excavation becomes unstable.
a.Temporarily stabilize the excavation by immediately placing an earth berm against the unstable excavation face.
b.Notify the Engineer immediately .
3.3 Soil Nail Installation
A.Drilling
1.Use core drilling, rotary drilling, percussion drilling, auger drilling, or driven casing.
a.Use a method that prevents loss of ground above the drilled hole that may be detrimental to the soil nails or existing structures.
b.Use a method that is suited to the ground conditions.
c.Use cased drilling methods or other suitable means to support the sides of the drill holes if needed. 1) Remove casing unless Engineer permits it to remain .
2.Drilled hole t olerances
a.Inclination 1) Within ±3 degrees of planned angle at the bearing plate
b.Location 1) Within ±0.5 ft of the planned location at the face of the excavated surface (point of entry).
c.Horizontal Splaying 1) Splay drill holes up to 10 degrees horizontally from plan orientation to avoid obstructions such as piles, drainage features, utilities, etc. 2) Note location of splayed nails and reason for splay on as-built drawings.
3.Adjust drill hole and soil nail length as necessary to develop the load capacity and satisfy acceptance criteria for the required design load if required by testing.
B.Tendon Insertion
1.Inspect bar coating or encapsulation on soil nail bars before insertion into the drill hole.
a.Replace soil nail bars exhibiting abrasions, cuts, welds, weld spatter, corrosion, or pitting.
b.Replace or repair soil nail bars exhibiting damage to bar coating or to encapsulation.
2.Space centralizers no greater than 10 ft apart and no more than 1.5 ft from the end of each nail.
a.Use centralizers that allow tremie pipe insertion to the bottom of the hole, and free flow of grout up the hole.
b.Attach to the bar in front of the couplings for HBSNs .
3.Insert soil nail tendon into the drilled hole without difficulty.
a.Remove the tendon and clean or redrill the drill hole to permit insertion if the tendon cannot be completely inserted.
b.Do not drive or force partially inserted bars into the hole.
4.Notify the Engineer and the Wall Designer immediately if soil nails cannot be installed as shown .
C.Grouting
1.Grout the drill hole after installation of the soil nail bar and within 2 hours of completing drilling.
2.Inject grout at the lowest point of each drill hole through a hollow bar soil nail, grout tube, casing, hollow -stem auger, or drill rods.
3.Place the outlet end of the grout delivery tube below the surface of the grout as the conduit is withdrawn to prevent the creation of voids.
4.Fill the drill hole in one continuous operation. Do not allow cold joints in the grout column except at the top of the test -bond length of proof -tested production nails.
5.Consider hollow bar soil nails to be completed when the final grout returns to the excavated face, signaling that drilling spoils have been removed.
6.Provide at least 1 inch of grout cover between the soil nail bar and the surrounding soil for all bars .
7.Fill bird’s beaks with additional grout after placing a temporary cover in front of the drill hole. Alternatively, fill bird’s beaks with shotcrete.
a.Position shotcrete nozzle into the mouth of the drill -hole to completely fill the void where shotcrete is used to backfill bird’s beaks .
8.Do not add water to grout conforming to the mix design to improve workability.
D.Nail Head Assembly
1.Attach a bearing plate, washers, and nut to each nail head as shown.
2.Provide uniform contact between the plate and the shotcrete.
a.Seat the bearing plate uniformly on the shotcrete while the facing is still plastic and before its initial set. Hand- wrench tighten the nut.
b.Set the bearing plate in a bed of grout if needed. Re-tighten the nut by hand with a wrench after the grout has set for 24 hours.
3.4 Soil Nail Testing
A.General
1.Conduct soil nail testing after the Wall Designer approves the calibration reports.
2.Perform soil nail testing after the nail grout and shotcrete facing have cured for at least 72 hours , and have attained their specified 3 day compressive strength.
3.Do not apply loads greater than the following:
a.Grade 75 or 80 bars: 90 percent of the minimum yield strength of the soil nail bar
b.Grade 150 bars: 80 percent of the minimum ultimate tensile strength of the soil nail bar
4.Use verification and p roof test nails having an unbonded length of at least 3 ft.
a.Clean out the hollow bar unbonded length after bar installation.
b.Do not place a PVC pipe bond breaker without cleanout as a substitute for providing the required unbonded length.
c.Measure and verify void for unbonded length before testing.
5.Provide verification test and proof test nails having a bonded length of at least 10 ft. Shorter bonded lengths are appropriate for proof tests on production nails less than 1 3 feet in length.
6.Immediately report f ailed verification and proof nail test result s to the Engineer and the Wall Designer, with the soil nail location, bonded and unbonded lengths, maximum load held, and the failure load.
B.Verification Testing
1.Perform verification tests on sacrificial nails at the locations shown.
a.Perform additional verification testing as determined by the Engineer.
b.Test nails of the same design and constructed with the same methods to be used on production nails.
2.Test sacrificial nails before installation of production soil nails to verify that the design nail pullout resistance is representative of the Contractor’s drilling and installation methods in the site soils.
3.Notify the Engineer of changes to drilling methods, installation methods, or equipment during installation of production nails.
a.Test additional sacrificial nails to address these changes as determined by the Engineer at no additional cost to the Department.
4.Test soil nails with a known bonded length and a measured unbonded length.
5.Select a bonded length, L BVT, as follows:
a.Calculate LVBTmax L BVTmax = (C RT x A t x fs) / (r po) EQ1 where: C RT = reduction coefficient ; 0.9 for Grade 75 or 80 bar or 0.8 for Grade 150 bar At = cross- sectional area of the test soil nail bar rpo = nominal load transfer rate (kips/ft) = π x qu x D dh / 12 qu = bond strength (ksf) Ddh = drill hole diameter (inch) fs = nominal resistance of the test tendon, f y or f u (ksi) in which: fy = nominal yield resistance of the test tendon (ksi) for Grade 75 or 80 bar fu = minimum ultimate tensile strength of the test tendon (ksi) for Grade 150 bar
b.If LVBTmax > 10 ft, 10 ft ≤ L VBT ≤ LVBTmax
c.If LVBTmax < 10 ft, L VBT = 10 ft, increase the test tendon size until L VBTmax ≥ 10 ft.
d.Use qu as shown .
e.Calculate the maximum load during the verification test, defined as the Verification Test Load (VTL), as follows: VTL = L BVT x rpo (kips/ft) EQ2 where: L BVT = verification test nail bonded length (ft)
6.Perform verification test by incrementally loading the verification test nail to pullout or maximum test load ( VTL) according to Table 1. Table 1 Verification Test Schedule Load Observation Period (minutes)3 AL1 Apply AL and set dial gauges to “zero”
0.13 VTL2 10 (record soil nail head movement at 1, 2, 5, 10)
0.25 VTL 10 (record soil nail head movement at 1, 2, 5, 10)
0.38 VTL 10 (record soil nail head movement at 1, 2, 5, 10)
0.50 VTL 10 (record soil nail head movement at 1, 2, 5, 10)
0.63 VTL 10 (record soil nail head movement at 1, 2, 5, 10)
0.75 Vtl
(Creep Test) 60 (record soil nail head movement at 1, 2, 5, 6, 10, 20, 30, 50, 60)
0.88 VTL 10 (record movement at 10)
1.00 VTL 10 (record movement at 10)
AL Reduce to AL And record permanent set Table Notes: 1 Alignment Load ( AL) ≤ 0.025 VTL (kips) 2 Verification Test Load (VTL) = L BVT x rpo (kips/ft) 3 Measure soil nail head movement after each load increment has been achieved and at each indicated time step
7.Maintain the load during the creep test to within 2 percent of the intended load by using a load cell.
8.Re-pump jack as needed to maintain load during hold times.
9.Reduce loading to the AL and record the permanent set after applying VTL or other maximum test load.
10.Perform stepped unloading where determined or authorized by the Wall Designer .
a.Perform between one and seven intermediate steps in stepped unloading.
b.Hold each load step until gage readings are stable.
C.Proof Testing
1.Perform proof testing on production soil nails.
a.Test at least 5 percent of production soil nails.
b.Test no fewer than one production nail per row on each soil nail wall. 1) Distribute the locations of proof tests evenly across the vertical and horizontal extent of the wall face.
c.Test the number of nails in each row sufficient to account for variability of soil and installation technique.
d.Proof test at least 10 percent of production soil nails, with no fewer than two proof tests per row on each soil nail wall where HBSNs are used without centralizers .
2.The Engineer will determine locations and number of proof tests before completing grout placement.
3.Demonstrate successful proof testing on at least 5 percent of production soil nails in each nail row , but no less than one per row.
4.Perform proof tests on soil nails with a known bonded length and a measured temporary unbonded length.
5.Select a bonded length (L BPT) for the proof tests such that L BPT is 10 ft or L BPTmax , whichever is smaller.
6.Select L BPTmax L BPTmax = (C RT x A t x fs) / (r po x 0.75) EQ3
7.Allow for bond lengths less than 10 ft for production proof nails shorter than 1 3 ft.
8.Do not proof test fully grouted nails .
9.Calculate the maximum load for proof tests, defined as the Proof Test Load (PTL), as follows: PTL = L BPT x rpo (kips/ft) x 0.75 EQ4
10.Conduct proof tests by incrementally loading the proof test nail according to the test loading schedule in Table 2. Table 2 Proof Test Schedule Load Observation Period (minutes)1 AL2 1
0.17 PTL3 Record movement when it stabilizes
0.33 PTL Record movement when it stabilizes
0.50 PTL Record movement when it stabilizes
0.67 PTL Record movement when it stabilizes
0.83 PTL Record movement when it stabilizes
1.0 PTL (Creep Test)4 10 (record soil nail head movement at 1, 2, 5, 6, and 10 minutes )
AL 1 Table Notes : Re-zero dial gages after the alignment load is applied. Re-pump jack as needed to maintain load within 5 percent of the intended load during hold times. 1 If the soils reinforced with nails are relatively susceptible to deformation or creep, hold each load increment for 10 minutes and record soil nail movement at 1, 2, 5, 6, and 10 minutes. 2 Alignment load ≤ 0.025 PTL 3 Proof Test Load (PTL) = L BPT x rpo (kips/ft) x 0.75 4 If soil nail movement measured between 1 and 10 minutes exceeds 0.04 inch, maintain PTL for 50 more minutes and record movements at 20, 30, 50, and 60 minutes. Record permanent soil movement.
3.5 Soil Nail Load Test Acceptance Criteria
A.A verification -tested or proof -tested soil nail is acceptable if all of the following are met:
1.The soil nail resists the creep test load with less than 0.04 inch of movement between the 1 minute and 10 minute readings .
2.The soil nail resists the creep test load with less than 0.08 inch of movement between the 6 minute and 60 minute readings if the creep test load is maintained for 60 minutes .
3.The creep rate is linear or decreasing throughout the creep test observation period.
4.The total soil nail movement ( ∆TL) measured at the maximum test load (VTL or PTL) exceeds 80 percent of the theoretical elastic elongation of the temporary unbonded length of the test nail, as calculated using Equation 5 (EQ5) . ∆TL > 0.8 x Max imum Test Load x L UB / (E x A t) EQ5 where: ∆TL = Total soil nail movement measured at the maximum test load (PTL or VTL) LUB = Test nail unbonded length E = Young’s Modulus of steel (29,000 ksi)
5.Pullout does not occur before achieving the maximum test load (VTL or PTL).
a.Pullout is defined as the load at which attempts to further increase the test load increment results in continued test nail movement.
B.Verification -tested Nail Failure
1.Modify the design or the installation procedures or both.
2.Install replacement sacrificial nails for verification testing.
C.Proof -tested Nail Failure
1.The production nail will be rejected.
2.The Engineer may determine that additional proof testing is required to delineate the area of unsatisfactory production nails.
3.Evaluate and modify the design and construction procedures as applicable.
3.6 Wall Drainage
A.Install and secure wall drainage elements.
1.Wall drainage elements include geocomposite strip drains , PVC connection pipes, soil nail wall toe drains, and weep holes .
2.Construct wall drainage to provide continuous and unrestricted flow to discharge water collected behind the wall face.
3.Install wall drainage elements before shotcreting with the exception of toe drains in front of the wall face.
B.Geocomposite strip drains
1.Center between each column of soil nails, as shown.
2.Provide a m inimum strip width of 12 inch.
3.Secure in continuous contact with the excavat ed face, and with the geotextile side against the excavated face.
4.Prevent shotcrete contamination of the geotextile against the excavated face.
C.Toe drains
1.Install at the bottom of the wall, according to the authorized soil nail retaining wall drawings .
2.Encase the free-draining granular backfill and pipe with drainage geotextile that conform s to the dimensions of the excavated trench.
3.7 Facing Joints
A.Construct expansion and contraction joints through the final shotcrete layer as shown. 3.8. CONSTRUCTION TOLERANCES
A.Refer to Table 3. Table 3 Construction Tolerances Item Tolerance Cross -sectional location for reinforcing steel, welded wire reinforcement, and shear connectors. 3/8 inch Location of headed studs on bearing plate ¼ inch Reinforcing steel lap 1 inch Planeness of finish surface, gap under 10 -ft straight edge, if troweled or screeded 9/16 inch Planeness of finish surface, gap under 10 -ft straight edge, if left as shot 1 1/8 inch Nail head bearing plate deviation from parallel to wall face 10 degrees
Source: Utah Standard Specifications for Road and Bridge Construction, 2026 Edition. Pages 761–781 of 1,331.