Standard Specifications for Road, Bridge, and Municipal Construction 2020 (M 41-10)

Page 6-188

6-05.3(11)H Pile Driving From or Near Adjacent Structures

The Contractor shall not drive piling from an existing Structure unless all of the following
conditions are met:
1.  The existing Structure will be demolished within the Contract;
2.  The existing Structure is permanently closed to traffic; and
3.  Type 2E Working Drawings are submitted in accordance with

Sections 1-05.3

and

6-02.3(16)

, showing the structural adequacy of the existing Structure to safely

support all of the construction loads.

Freshly placed concrete in the vicinity of the pile driving operation shall be protected
against vibration in accordance with

Section 6-02.3(6)D

6-05.3(12) Determination of Bearing Values

The following formula shall be used to determine ultimate bearing resistances:

P = F × E × Ln(10N)

Where:

= ultimate bearing resistance, in tons

= 1.8 for air/steam hammers

= 1.2 for open ended diesel hammers and precast concrete or timber piles

= 1.6 for open ended diesel hammers and steel piles

= 1.2 for closed ended diesel hammers

= 1.9 for hydraulic hammers

= 0.9 for drop hammers

= developed energy, equal to W times H

, in ft-kips

= weight of ram, in kips

= vertical drop of hammer or stroke of ram, in feet

= average penetration resistance in blows per inch for the last 4 inches of driving

= the natural logarithm, in base “e”

For closed-end diesel hammers (double-acting), the developed hammer energy (E) is to be determined

from the bounce chamber reading. Hammer manufacturer calibration data may be used to correlate bounce

chamber pressure to developed hammer energy. For double acting hammer hydraulic and air/steam

hammers, the developed hammer energy shall be calculated from ram impact velocity measurements or

other means acceptable to the Engineer. For open ended diesel hammers (single-acting) use the blows per

minute to determine the developed energy (E).

The above formula applies only when:
1.  The hammer is in good condition and operating in a satisfactory manner.
2.  A follower is not used.
3.  The pile top is not damaged.
4.  The pile head is free from broomed or crushed wood fiber.
5.  The penetration occurs at a reasonably quick, uniform rate; and the pile has been

driven at least 2 feet after any interruption in driving greater than 1 hour in length.

Piling 6-05

6. There is no perceptible bounce after the blow. If a significant bounce cannot be

avoided, twice the height of the bounce shall be deducted from “H” to determine its
true value in the formula.

7. For timber piles, bearing resistances calculated by the formula above shall be

considered effective only when it is less than the crushing strength of the piles.

8. If “N” is greater than or equal to 1.0 blow/inch.

If “N” required to achieve the required ultimate bearing resistance using the above
formula is less than 1.0 blow/inch, the pile shall be driven until the penetration resistance
is a minimum of 1.0 blow/inch for the last 2 feet of driving.

The Engineer may require the Contractor to install a pressure gauge on the inboard end of
the hose to check pressure at the hammer.

If water jets are used in driving, bearing resistances shall be determined either: (1)
by calculating it with the driving data and the formula above after the jets have been
withdrawn and the pile is driven at least 2 feet, or (2) by applying a test load.

6-05.3(13) Treatment of Timber Pile Heads

After cutting timber piles to correct elevation, the Contractor shall thoroughly coat the
heads of all untreated piles with two coats of an approved preservative that meets the
requirements of

Section 9-09

(except concrete-encased piles).

After cutting treated timber piles to correct elevation, the Contractor shall brush three
coats of a preservative that meets the requirements of

Section 9-09

on all pile heads

(except those to be covered with concrete footings or concrete caps). The pile heads shall
then be capped with alternate layers of an approved roofing asphalt and a waterproofing
fabric that conforms to

Section 9-11.2

. The cap shall be made of four layers of an

approved roofing asphalt and three layers of fabric. The fabric shall be cut large enough
to cover the pile top and fold down at least 6 inches along all sides of the pile. After
the fabric cover is bent down over the pile, its edges shall be fastened with large-head
galvanized nails or with three turns of galvanized wire. The edges of the cover shall be
neatly trimmed.

On any treated timber pile encased in concrete, the cut end shall receive two coats of
an approved preservative that meets the requirements of

Section 9-09

and then a heavy

coat of an approved roofing asphalt.

6-05.3(14) Extensions and Buildups of Precast Concrete Piles

The Contractor shall add extensions, or buildups (if necessary) on precast concrete
piles after they are driven to the required ultimate bearing resistance and minimum tip
elevation.

Before adding extensions or buildups to precast-prestressed piles, the Contractor shall
remove any spalled concrete, leaving the pile fresh-headed and with a top surface
perpendicular to the axis of the pile. The concrete in the buildup shall be Class 5000.

Page 6-190

Before adding to non-prestressed precast concrete piles, the Contractor shall cut the
pile head away to a depth 40 times the diameter of the vertical reinforcing bar. The final
cut shall be perpendicular to the axis of the pile. Reinforcement of the same density and
configuration as used in the pile shall be used in the buildup and shall be fastened firmly
to the projecting steel. Forms shall be placed to prevent concrete from leaking along the
pile. The concrete in the buildup shall be Class 4000.

Just before placing the concrete for extensions or buildups to precast or precast-
prestressed concrete piles, the Contractor shall thoroughly wet the top of the pile. Forms
shall remain in place at least 3 days.

6-05.3(15) Completion of Cast-In-Place Concrete Piles

After acceptance by the Engineer, driven casings shall be cut off horizontally at the
required elevation. They shall be clean and free of water when concrete and reinforcing
steel are placed.

These piles shall consist of steel casings driven into the ground, reinforced as specified,
and filled with Class 4000P concrete.

6-05.3(15)A Reinforcement

All bars shall be fastened rigidly into a single unit, then lowered into the casing before the
concrete is placed. Loose bars shall not be used.

Spiral hooping reinforcement shall be deformed steel bar, plain steel bar, cold-drawn wire,
or deformed wire.

6-05.3(15)B

Placing Concrete

Before placing concrete, the Contractor shall remove all debris and water from the casing.
If the water cannot be removed, the casing shall be removed (or cut off 2 feet below the
ground and filled with sand) and a new one driven.

The Contractor shall place concrete continuously through a 5-foot rigid conduit directing
the concrete down the center of the pile casing, ensuring that every part of the pile is
filled and the concrete is worked around the reinforcement. The top 5 feet of concrete
shall be placed with the tip of the conduit below the top of fresh concrete. The Contractor
shall vibrate, as a minimum, the top 10 feet of concrete. In all cases, the concrete shall be
vibrated to a point at least 5 feet below the original ground line.

6-05.4 Measurement

Measurement for driving (type) pile will be the number of piles driven in place.

In these categories, measurement will be the longer of either the number of linear feet
driven below cutoff or as shown in the Engineer’s order list:
1. Furnishing timber piling (untreated or name of treatment).
2. Precast concrete and precast-prestressed concrete piling.

Piling 6-05

In these categories, measurement will be the number of linear feet driven below cutoff,
but no Engineer’s order list will be provided:
1. Cast-in-place concrete piling.
2. Furnishing steel piling.

Measurement for furnishing and driving test piles will be the number actually furnished
and driven as the Contract requires.

Measurement for steel pile tips or shoes will be by the number of tips or shoes actually
installed and driven in place on steel casings or steel piles.

6-05.5 Payment

Payment will be made for each of the following Bid items that are included in the
Proposal:

“Furnishing and Driving (type) Test Pile”, per each.
The unit Contract price per each for “Furnishing and Driving (type) Test Pile” shall
be full pay for furnishing and driving test piles to the ultimate bearing resistance or
penetration required by the Engineer, furnishing and installing a pile tip when pile
tips are specified for the permanent piles, preboring when preboring is specified
for the permanent piles, for pulling the piles or cutting them off as required, and for
removing them from the site or for delivery to the Contracting Agency for salvage
when ordered by the Engineer. For cast-in-place concrete test piles, this price shall
include furnishing, fabricating, and installing the steel reinforcing bar cage, and
furnishing, casting, and curing the concrete. This price shall also include all costs in
connection with moving all pile driving equipment or other necessary equipment
to the site of the Work and for removing all such equipment from the site after the
piles have been driven. If, after the test piles have been driven, it is found necessary
to eliminate the piling from all or any part of the Structure, no additional pay will be
allowed for moving the pile driving equipment to and from the site of the Work.
“Driving Timber Pile (untreated or name treatment)”, per each.
The unit Contract price per each for “Driving Timber (type) Pile” shall include any
metal shoes which the Contractor has determined to be beneficial to the pile driving.
“Driving Conc. Pile (size)”, per each.
“Driving St. Pile”, per each.
The unit Contract price per each for “Driving (type) Pile (____)” shall be full pay for
driving the pile to the ultimate bearing and/or penetration specified.
“Furnishing Timber Piling (untreated or name treatment)”, per linear foot.
“Furnishing Conc. Piling (size)”, per linear foot.
“Furnishing St. Piling”, per linear foot.
The unit Contract price per linear foot for “Furnishing (type) Piling (____)” shall be full
pay for furnishing the piling specified, including furnishing, fabricating, and installing

Page 6-192

the steel reinforcing bar cage, and furnishing casting, and curing the concrete, as
required for concrete piling. Such price shall also be full pay, for furnishing timber,
precast concrete, or precast-prestressed concrete piling length ordered from an
Engineer’s order sheet but not driven.
“Precast Concrete Pile Buildup”, by force account.
Payment for buildups of precast or precast-prestressed concrete piles will be made
on the basis of force account Work as covered in

Section 1-09.6

. No payment will

be made for buildups or additional lengths of buildup made necessary because of
damage to the piling during driving. The length of splice for precast concrete piles
includes the length cut off to expose reinforcing steel for the splice. The length of
splice for precast-prestressed piles includes the length in which holes are drilled and
reinforcing bars are grouted.
For the purpose of providing a common Proposal for all Bidders, the Contracting
Agency entered an amount for “Precast Concrete Pile Buildup” in the Proposal to
become part of the total Bid by the Contractor.
“Furnishing Steel Pile Tip or Shoe (size)”, per each.

6-06

Bridge Railings

6-06.1 Description

This Work consists of providing and building bridge railings that meet the requirements
of the Plans, these Specifications, and the Engineer.

6-06.2 Materials

Materials shall meet the requirements of the following sections:

Timber Railing

9-09

Metal Railing

9-06.18

6-06.3

Construction Requirements

6-06.3(1) Timber Railings

Wheel guards and railings shall be true to line and grade and framed accurately.
The Contractor shall follow

Section 6-04

whenever this Subsection does not specify

a construction method.

Unless the Plans show otherwise, wheel guards shall be:
1. Beveled and surfaced on the Roadway side and surfaced on the top edge.

They may be surfaced on four sides (S4S).

2. Laid in sections at least 12 feet long.
3. Bolted through the floor plank and outside stringer (or nailing piece) with ¾ inch

diameter bolts spaced no more than 4 feet apart.

All rails and rail post material shall be S4S and painted as required in

Section 6-07

. Railing

members shall be fastened securely together, with the bolts tightened once at installation
and again just before the Contracting Agency’s final acceptance of the Contract.

6-06.3(2) Metal Railings

Metal railing includes posts, web members, and horizontal members of the sidewalk
and Roadway railing. Unless the Plans or Special Provisions show otherwise, these shall
be made of aluminum alloy or steel.

Before fabricating the railing, the Contractor shall submit Type 2 Working Drawings of the
shop plans. The Contractor may substitute other rail connection details for those shown
in the Plans if details of these changes show in the shop plans and if the Engineer accepts
them in the Working Drawing response comments. In reviewing the shop plans, the
Engineer indicates only that they are adequate and complete enough. The review does
not indicate a check on dimensions.

Page 6-194

Bridge Railings

Anchor bolts shall be positioned with a template to ensure that bolts match the hole
spacing of the bottom channels or anchorage plates.

Where specified, cover plates shall fit the bottom channel tightly after being snapped
into position.

Metal railings shall be installed true to line and grade (or camber). After first setting
the railing, the Contractor shall readjust all or part of it, if necessary, to create an overall
line and grade pleasing to the eye.

6-06.4 Measurement

Timber railing will be measured by the thousand board feet (MBM) as shown in

Section 6-04

Metal railing will be measured by the linear foot along the line and slope at the base
of the completed railing.

6-06.5 Payment

Payment will be made for each of the following Bid items that are included in the
Proposal:

“Timber and Lumber (untreated or name treatment)”, per MBM.
“Bridge Railing Type ____”, per linear foot.
In case no item is included in the Contract for “Bridge Railing Type ____” and
payment is not otherwise provided, all metal railings shall be included in the lump
sum Contract price for “Structural Carbon St”. as specified in

Section 6-03

Page 6-294

Geosynthetic Retaining Walls

All costs in connection with constructing the concrete fascia panels as specified shall
be included in the unit Contract price per square foot for “Concrete Fascia Panel
For Geosynthetic Wall”, including all steel reinforcing bars, premolded joint filler,
polyethylene bond breaker strip, joint sealant, PVC pipe for weep holes, exterior
surface finish, and pigmented sealer (when specified), constructing and placing the
concrete footing, edge beam, anchor beam, anchor rod assembly, and backfill.
Shotcrete facing will be paid for in accordance with

Section 6-18.5

“Geosynthetic Wall Single Slope Traffic Barrier”, per linear foot.
“Geosynthetic Wall F-Shape Traffic Barrier”, per linear foot.
“Geosynthetic Retaining Wall Pedestrian Barrier”, per linear foot.
The unit Contract price per linear foot for “Geosynthetic Wall Single Slope Traffic
Barrier”, “Geosynthetic Wall F-Shape Traffic Barrier”, and “Geosynthetic Retaining
Wall Pedestrian Barrier” shall be full pay for constructing the barrier on top of the
geosynthetic retaining wall.

Soil Nail Walls

6-15

Soil Nail Walls

6-15.1 Description

This Work consists of constructing soil nail walls.

6-15.2 Materials

Materials shall meet the requirements of the following sections:
Grout

9-20.3(4)

Prefabricated Drainage Mat

9-33.2(3)

Other materials required, including materials for soil nails, shall be as specified in the
Special Provisions.

6-15.3

Construction Requirements

6-15.3(1) General Description

Soil nailing shall consist of excavating to the layer limits shown in the Plans, drilling holes
at the specified angle into the native material, placing and grouting epoxy coated or
encapsulated steel reinforcing bars (soil nails) in the drilled holes, placing prefabricated
drainage material and steel reinforcement, and applying a shotcrete facing over the steel
reinforcement. After completing the wall to full height, the Contractor shall construct the
concrete fascia panels as shown in the Plans.

All proprietary items used in the soil nailed Structure shall be installed in accordance
with the manufacturer’s recommendations. In the event of a conflict between the
manufacturer’s recommendations and these Specifications, these Specifications
shall prevail.

6-15.3(2) Contractor’s Experience Requirements

The Contractor or Subcontractor performing this Work shall have completed at least five
projects, within the last 5 years, involving construction of retaining walls using soil nails or
ground anchors or shall have completed the construction of two or more projects totaling
at least 15,000 square feet of retaining wall with a minimum total of 500 soil nails or
ground anchors.

The Contractor shall assign an engineer with at least 3 years of experience in the design
and construction of permanently anchored or nailed Structures to supervise the Work.
The Contractor shall not use consultants or manufacturer’s representatives in order to
meet the requirements of this Section. Drill operators and on-site supervisors shall have a
minimum of 1 year experience installing permanent soil nails or ground anchors.

Contractors or Subcontractors that are specifically prequalified in Class 36 Work will be
considered to have met the above experience requirements.

Page 6-296

Soil Nail Walls

6-15.3(3) Submittals

The Contractor shall submit Type 2 Working Drawings of the following information.
1. A brief description of each project satisfying the Contractors Experience

Requirements with the Owner’s name and current phone number (this item is not
required if the Contractor or Subcontractor is prequalified in Class 36).

2. A list identifying the following personnel assigned to this project and their

experience with permanently anchored or nailed Structures:
a.  Supervising Engineer.
b.  Drill Operators.
c.  On-site Supervisors who will be assigned to the project.

3. The proposed detailed construction procedure that includes:

a. Proposed method(s) of excavation of the soil and/or rock.
b. A plan for the removal and control of groundwater encountered during

excavation, drilling, and other earth moving activities. Include a list of the
equipment used to remove and control groundwater.

Proposed drilling methods and equipment.

d. Proposed hole diameter(s).
e. Proposed method of soil nail installation.
f.

Mix design and procedures for placing the grout.

g. Shotcrete mix design with compressive strength test results.
h. Procedures for placing the shotcrete (include placement in conditions when

ground water is encountered).

Encapsulation system for additional corrosion protection selected for the soil
nails and anchorages requiring encapsulation.

4. Detailed Working Drawings of the method proposed for the soil nail testing that

includes:
a. All necessary drawings and details to clearly describe the proposed system of

jacking support, framing, and bracing to be used during testing.

b. Calibration data for each load cell, test jack, pressure gauge, stroke counter on

the grout pump, and master gauge to be used. The calibration tests shall have
been performed by an independent testing Laboratory, and tests shall have
been performed within 60 calendar days of the date submitted. Testing or Work
shall not commence until the Engineer has approved the load cell, jack, pressure
gage, and master pressure gauge calibrations.

5. Certified mill test results and typical stress-strain curves along with samples from

each heat, properly marked, for the soil nail steel. The typical stress-strain curve shall
be obtained by approved standard practices. The guaranteed ultimate strength, yield
strength, elongation, and composition shall be specified.

Soil Nail Walls

6-15

6-15.3(4) Preconstruction Conference

A soil nail preconstruction conference shall be held at least 5 working days prior to the
Contractor beginning any permanent soil nail Work at the site to discuss construction
procedures, personnel and equipment to be used. The list of materials specified on the
Record of Materials Form (ROM) for this item of Work will also be discussed. Those
attending shall include:
1. (representing the Contractor) The superintendent, on site supervisors, and all

foremen in charge of excavating the soil face, drilling the soil nail hole, placing the
soil nail and grout, placing the shotcrete facing, and tensioning and testing the
soil nail.

2. (representing the Contracting Agency) The Engineer, key inspection personnel, and

representatives from the WSDOT Construction Office and Materials Laboratory
Geotechnical Services Branch.

If the Contractor’s key personnel change, or if the Contractor proposes a significant
revision of the approved permanent soil nail installation plan, an additional conference
shall be held before any additional permanent soil nail operations are performed.

6-15.3(5) Earthwork

The ground contour above the wall shall be established to its final configuration and slope
as shown in the Plans prior to beginning excavation of the soil for the first row of soil
nails. All excavation shall conform to

Section 2-03

The excavation shall proceed from the top down in a horizontal lift sequence with the
ground level excavated no more than 3 feet below the elevation of the row of nails to
be installed in that lift. The excavated vertical wall face shall not be left unshored more
than 24 hours for any reason. A lift shall not be excavated until the nail installation and
reinforced shotcrete placement for the preceding lift has been completed and accepted.
After a lift is excavated, the cut surface shall be cleaned of all loose materials, mud,
rebound, and other foreign matter that could prevent or reduce shotcrete bond.

The accuracy of the ground cut shall be such that the required thickness of shotcrete can
be placed within a tolerance of plus or minus 2 inches from the defined face of the wall,
and over excavation does not damage overlying shotcrete sections by undermining or
other causes.

The Contractor should review the geotechnical recommendations report prepared for this
project for further information on the soil conditions at the location of each wall. Copies
of the geotechnical recommendations report are available for review by prospective
Bidders at the location identified in the Special Provisions.

Page 6-298

Soil Nail Walls

6-15.3(6) Soil Nailing

The Contractor shall not handle and transport the encapsulated soil nails until the
encapsulation grout has reached sufficient strength to resist damage during handling.
The Contractor shall handle the encapsulated soil nails in such a manner to prevent large
deflections or distortions during handling. When handling or transporting encapsulated
soil nails, the Contractor shall provide slings or other equipment necessary to prevent
damage to the soil nails and the corrosion protection. The Engineer may reject any
encapsulated nail which is damaged during transportation or handling. Damaged
or defective encapsulation shall be repaired in accordance with the manufacturer’s
recommendations.

Soil nails shall be handled and sorted in such a manner as to avoid damage or corrosion.
Prior to inserting a soil nail in the drilled hole, the Contractor and the Engineer will
examine the soil nail for damage. If, in the opinion of the Engineer, the epoxy coating or
bar has been damaged, the nail shall be repaired. If, in the opinion of the Engineer, the
damage is beyond repair, the soil nail shall be rejected.

If, in the opinion of the Engineer, the epoxy coating can be repaired, the Contractor shall
patch the coating with an Engineer approved patching material.

Nail holes shall be drilled at the locations shown in the Plans or as staked by the Engineer.
The nails shall be positioned plus or minus 6 inches from the theoretical location shown in
the Plans. The Contractor shall select the drilling method and the grouting pressure used
for the installation of the soil nail. The drill hole shall be located so that the longitudinal
axis of the drill hole and the longitudinal axis of the nail are parallel. At the point of entry
the soil nail shall be installed within plus or minus 3 degrees of the inclination from
horizontal shown in the Plans, and the nail shall be within plus or minus 3 degrees of a
line drawn perpendicular to the face of the wall unless otherwise shown in the Plans.

Water or other liquids shall not be used to flush cuttings during drilling, but air may be
used. The nail shall be inserted into the drilled hole with centralizers to the desired depth
in such a manner as to prevent damage to the drilled hole, sheathing or epoxy during
installation. The centralizers shall provide a minimum of 0.5 inches of grout cover over
the soil nail and shall be spaced no further than 8 feet apart. When the soil nail cannot be
completely inserted into the drilled hole without difficulty, the Contractor shall remove
the nail from the drilled hole and clean or redrill the hole to permit insertion. Partially
inserted soil nails shall not be driven or forced into the hole. Subsidence, or any other
detrimental impact from drilling shall be cause for immediate cessation of drilling and
repair of all damages in a manner approved by the Engineer at no additional cost to the
Contracting Agency.

If caving conditions are encountered, no further drilling will be allowed until the
Contractor selects a method to prevent ground movement. The Contractor may use
temporary casing. The Contractor’s method to prevent ground movement shall be
approved by the Engineer. The casings for the nail holes, if used, shall be removed as the
grout is being placed.

Soil Nail Walls

6-15

Where necessary for stability of the excavation face, a sealing layer of shotcrete may be
placed before drilling is started, or the Contractor shall have the option of drilling and
grouting of nails through a stabilizing berm of native soil at the face of the excavation.
The stabilizing berm shall extend horizontally from the soil face and from the face of
the shotcrete a minimum distance of 1 foot, and shall be cut down from that point at
a safe slope, no steeper than 1H:1V unless approved by the Engineer. The berm shall
be excavated to final grade after installation and full length grouting of the nails. Nails
damaged during berm excavation shall be repaired or replaced by the Contractor, to the
satisfaction of the Engineer, at no added cost to the Contracting Agency.

If sections of the wall are constructed at different times than the adjacent soil nail
sections, the Contractor shall use stabilizing berms, temporary slopes, or other
measures acceptable to the Engineer, to prevent sloughing or failure of the adjacent soil
nail sections.

If cobbles and boulders are encountered at the soil face during excavation, the Contractor
shall remove all cobbles and boulders that protrude from the soil face into the design wall
section and fill the void with shotcrete. All shotcrete used to fill voids created by removal
of cobbles and boulders shall be incidental to shotcrete facing.

The grout equipment shall produce a grout free of lumps and undispersed cement.
A positive displacement grout pump shall be used. The pump shall be equipped with
a pressure gauge near the discharge end to monitor grout pressures. The pressure
gauge shall be capable of measuring pressures of at least 150 psi or twice the actual
grout pressures used by the Contractor, whichever is greater. The grouting equipment
shall be sized to enable the grout to be pumped in one continuous operation. The mixer
shall be capable of continuously agitating the grout.

The grout shall be injected from the lowest point of the drilled hole. The quantity of the
grout and the grout pressures shall be recorded. The grout pressures and grout takes
shall be controlled to prevent excessive ground heave.

The Contractor shall make and cure grout cubes once per day in accordance with WSDOT

T 813

. These samples shall be retained by the Contractor until all associated verification

and proof testing of the soil nails has been successfully completed. If the Contractor
elects to test the grout cubes for compressive strength, testing shall be conducted by
an independent laboratory and shall be in accordance with the FOP for AASHTO T106.

6-15.3(7) Shotcrete Facing

Prior to placing any shotcrete on an excavated layer, the Contractor shall vertically
center prefabricated drainage mat between the columns of nails as shown in the Plans.
The prefabricated drainage mat shall be installed in accordance with the manufacturer’s
recommendations. The permeable drain side shall be placed against the exposed soil
face. The prefabricated drainage mat shall be installed after each excavation lift and shall
be hydraulically connected with the prefabricated drainage mat previously placed, such
that the vertical flow of water is not impeded. The Contractor shall tape all joints in the
prefabricated drainage mat to prevent shotcrete intrusion during shotcrete application.

Page 6-300

Soil Nail Walls

The Contractor shall place steel reinforcing bars and welded wire fabric, and apply the
shotcrete facing in accordance with

Section 6-18

and the details shown in the Plans.

The shotcrete shall be constructed to the minimum thickness as shown in the Plans. Costs
associated with additional thickness of shotcrete due to over excavation or irregularities
in the cut face shall be borne by the Contractor.

Each soil nail shall be secured at the shotcrete facing with a steel plate as shown in the
Plans. The plate shall be seated on a wet grout pad of a pasty consistency similar to that
of mortar for brick-laying. The nut shall then be sufficiently tightened to achieve full
bearing surface behind the plate. After the shotcrete and grout have had time to gain the
specified strength, the nut shall be tightened with at least 100 foot-pounds of torque.
After final tightening of the nut, the threads of the soil nail shall at a minimum be flush
with the end of the nut.

6-15.3(8) Soil Nail Testing and Acceptance

Both verification and proof testing of the nails is required. The Contractor shall supply all
materials, equipment, and labor to perform the tests. The Contractor shall submit Type
1 Working Drawings of all test data. Soil nails used for verification tests and proof tests
shall not be production soil nails, but instead shall be separate sacrificial soil nails not
otherwise incorporated into the Work.

The testing equipment shall include a dial gauge or vernier scale capable of measuring to
0.001 inch of the ground anchor movement. A hydraulic jack and pump shall be used to
apply the test load. The movement-measuring device shall have a minimum travel equal
to the theoretical elastic elongation of the total nail length plus 1 inch. The dial gauge or
vernier scale shall be aligned so that its axis is within 5 degrees from the axis of the nail
and shall be monitored with a reference system that is independent of the jacking system
and excavation face.

The jack and pressure gauge shall be calibrated by an independent testing Laboratory
as a unit. Each load cell, test jack and pressure gauge, grout pump stroke counter, and
master gauge, shall be calibrated as specified in

Section 6-15.3(3)

, item 4b. Additionally,

the Contractor shall not use load cells, test jacks and pressure gauges, grout pump stroke
counters, and master gauges, greater than 60 calendar days past their most recent
calibration date, until such items are re-calibrated by an independent testing Laboratory.

The pressure gauge shall be graduated in increments of either 100 psi or 2 percent of
the maximum test load, whichever is less. The pressure gauge shall be selected to place

the maximum test load within the middle ⅔ of the range of the gauge. The ram travel of

the jack shall not be less than the theoretical elastic elongation of the total length at the
maximum test load plus 1 inch. The jack shall be independently supported and centered
over the nail so that the nail does not carry the weight of the jack. The Contractor shall
have a second calibrated jack pressure gauge at the site. Calibration data shall provide a
specific reference to the jack and the pressure gauge.

Soil Nail Walls

6-15

The loads on the nails during the verification and proof tests shall be monitored to
verify consistency of load – defined as maintaining the test load within 5 percent of the
specified value. Verification and proof test loads less than 20,000 pounds or sustained for
5 minutes or less shall be monitored by the jack pressure gauge alone. Verification and
proof test loads equal to or greater than 20,000 pounds and sustained for longer than
5 minutes shall be monitored with the assistance of an electric or hydraulic load cell. The
Contractor shall provide the load cell, the readout device, and a calibration curve from
the most recent calibration as specified in

Section 6-15.3(3)

, item 4b. The load cell shall

be selected to place the maximum test load within the middle ⅔ of the range of the load

cell. The load cell shall be mounted between the jack and the anchor plate. The stressing
equipment shall be placed over the nail in such a manner that the jack bearing plates, load
cell and stressing anchorage are in alignment.

Nails to be tested shall be initially grouted no closer to the excavation face than the
dimension shown in the Plans. After placing the grout, the nail shall remain undisturbed
until the grout has reached strength sufficient to provide resistance during testing. Test
nails shall be left in the ground after testing, with the exposed portion of the test nail cut
and removed to 2 feet behind the excavated face or inside face of shotcrete. The drill
holes for test nails shall be completely backfilled with grout or nonstructural filler after
testing on those test nails has been completed.

Load testing shall be performed against a temporary reaction frame with bearing pads
that bear directly against the existing soil or the shotcrete facing. Bearing pads shall be
kept a minimum of 12 inches from the edges of the drilled hole and the load shall be
distributed to prevent failure of the soil face or fracture of the shotcrete. The Contractor
shall submit Type 2E Working Drawings of the reaction frame.

The soil nail load monitoring procedure for verification and proof test load greater than
20,000 pounds and sustained for longer than 5 minutes shall be as follows:
1. For each increment of load, attainment of the load shall be initially established and

confirmed by the reading taken from the jack gauge.

2. Once the soil nail anchor load has been stabilized, based on the jack gauge reading,

the load cell readout device shall immediately be read and recorded to establish the
load cell reading to be used at this load. The load cell reading is intended only as a
confirmation of a stable soil nail load, and shall not be taken as the actual load on the
soil nail.

3. During the time period that the load on the soil nail is held at this load increment,

the Contractor shall monitor the load cell reading. The Contractor shall adjust the
jack pressure as necessary to maintain the initial load cell reading. Jack pressure
adjustment for any other reason will not be allowed.

4. Soil nail elongation measurements shall be taken at each load increment as specified

in Sections

6-15.3(8)A

and

6-15.3(8)B

5. Steps 1 through 4 shall be repeated at each increment of load, in accordance with

the load sequence specified in Sections

6-15.3(8)A

and

6-15.3(8)B

Page 6-302

Soil Nail Walls

6-15.3(8)A

Verification Testing

Verification testing shall be performed on nails installed within the pattern of production
nails to verify the Contractor’s procedures, hole diameter, and design assumptions. No
drilling or installation of production nails will be permitted in any ground/rock unit unless
successful verification testing of anchors in that unit has been completed and approved
by the Engineer, using the same equipment, methods, nail inclination, nail length, and
hole diameter as planned for the production nails. Changes in the drilling or installation
method may require additional verification testing as determined by the Engineer and
shall be done at no additional expense to the Contracting Agency. Verification tests may
be performed prior to excavation for the soil nail wall.

Successful verification tests are required within the limits as specified in the Special
Provisions. Test nail locations within these limits shall be at locations selected by
the Engineer.

The Contractor shall submit Type 2E Working Drawings consisting of design details of
the verification testing, including the system for distributing test load pressures to the
excavation surface and appropriate nail bar size and reaction plate. The intent is to stress
the bond between the grout and the surrounding soil/rock to at least twice the design
load transfer. Prior to beginning verification testing, the Contractor shall measure and
record the length of the nonbonded zone for each verification test soil nail.

The bar shall be proportioned such that the maximum stress at 200 percent of the test
load does not exceed 80 percent of the yield strength of the steel. The jack shall be
positioned at the beginning of the test such that unloading and repositioning of the jack
during the test will not be required. The verification tests shall be made by incrementally
loading the nails in accordance with the following schedule of hold time:

1 minute

0.25TL

10 minutes

0.50TL

10 minutes

0.75TL

10 minutes

1.00TL

10 minutes

1.25TL

10 minutes

1.50TL

60 minutes

1.75TL

10 minutes

2.00TL

10 minutes

AL = Nail Alignment Load
TL = Nail Test Load

The test load shall be determined by the following equation = Test Load (TL) = Bond
Length (BL) × Design Load Transfer (DLT).

The load shall be applied in increments of 25 percent of the test load. Each load
increment shall be held for at least 10 minutes. Measurement of nail movement shall be
obtained at each load increment. The load-hold period shall start as soon as the load is
applied and the nail movement with respect to a fixed reference shall be measured and
recorded at 1 minute, 2, 3, 4, 5, 6, 10, 20, 30, 40, 50, and 60 minutes.

Standard Specifications for Road, Bridge, and Municipal Construction 2020 (M 41-10) - page 69