617Permanent Anchored Walls

617.1General Description

This work includes furnishing materials, labor, tools, equipment, and other incidental items to design, detail, and construct an anchored wall. This specification applies to any Contractor-proposed alternate design of Department- furnished plans. 617.1.01 Definitions Anchor—Synonymous with the terms tie-back or tie-down. The term Anchored Wall includes the following items: • Anchors • Soldier piles • Lagging • Facing • Drainage 617.1.02 Related References

General Provisions 101 through 150. 617.1.03 Submittals

Submit the following proof of ability (or ability of the Subcontractor) when requested by the Department to design or construct anchored walls: • Evidence of successfully completing at least 5 Projects similar in concept and scope to the proposed wall. • Resumes of foremen, anchor testing personnel, and drilling operators to be employed on this Project. Show the type, length, and number of ground anchors each has installed or tested within the past 5 years. • Evidence of experience in anchor testing. Persons performing anchor testing must prove experience by performing sample tests supervised by the Engineer. The Department is the sole judge of the qualifications of the foreman, drilling operator, and testing personnel. Do not begin wall construction until the Engineer has approved proof of ability.

If the Department receives more than 2 submittals of the plans and calculations for review, the Contractor will be assessed $60 per hour of engineering time for reviews in excess of the 2 submittals.

If a Contractor-proposed alternate anchored wall is a part of the low bid, submit construction drawings and design notes within 28 days of the date of award of the Contract. The Design Engineer shall prepare and stamp the submission. 987 987 987 987 987

Include design notes and reproducible drawings in the submission concerning the following: • Details, dimensions, and schedules of reinforcing steel, including dowels or studs for attaching the facing to the tied back wall • Details of the anchors and soldier piling, including spacing and size of piles and spacing and angle of anchor installation • Detailed plans for anchor proof and performance testing that show loading and measuring devices used and procedures followed

Submit final wall plans and calculations to the Department for review and approval before beginning construction on the wall the time required for plan and calculation preparation and review will be charged to the allowable Contract time. The Department has 30 days for plan and calculation review per Item after receiving the structure calculations and drawings. New submittals from the Contractor showing corrections from the Department’s review or changes to ease construction or to correct field errors have a 30-day review. The Department is the sole judge of information adequacy. The Department’s review and acceptance of the final plans and construction methods does not relieve the Contractor from successfully completing the work. Time extensions are not granted for Contractor delays from untimely submissions and insufficient information.

Before using an admixture, submit to the Engineer the manufacturer’s literature. Indicate the admixture type and the manufacturer’s recommendations for mixing the admixtures with grout.

Submit to the Engineer the mill test reports for each heat or lot of prestressing material used to fabricate tendons.

617.2Materials

Use concrete that conforms to Section 500.

Use reinforcing steel that conforms to Section 511.

Use structural steel as follows:

722, Type II. Do not use couplers. Ensure material requirements, coating application, and epoxy coating sampling and testing conform to Section 514.

Produce cement grout using Portland cement that conforms to AASHTO M 85, Type I, II, or III, and potable water. Use cement that is fresh and free of lumps and hydration. Follow these restrictions if using admixtures:

988 988 988 988 988

bleeding in the cement grout.

For corrosion protection, use polypropylene plastic that conforms to designation grade II 26500D as per ASTM D- 2146. Ensure that the environmental stress crack resistance of the material prevents failures at 1,000 hours when tested by ASTM D-1693.

Use corrosion inhibitor (grease) that conforms to the following test requirements: • Drop point 300 °F (149 °C) minimum by ASTM D-566 • Flash point 300 °F (149 °C) minimum by ASTM D-92 • Water content 0.1 percent maximum by ASTM D-95 • Rust grade 7 or better after 720 hours, aggressive conditions: rust grade 7 or better after 1,000 hours by ASTM B-117 and ASTM D-610 Water-solubleions must follow these requirements:

solution and expose to 5 percent salt fog—no emulsification after 720 hours—by ASTM B-117 modified.) Chlorides 10 ppm max by ASTM B-512 Nitrates 10 ppm max by ASTM D-992 Sulfates 10 ppm max by APHA427D 617.2.01 Delivery, Storage, and Handling

Protect prestressed rock and soil anchors against corrosion by properly storing, fabricating, and handling the tendon components before inserting them into the borehole. Avoid prolonged exposure of the tendon components to the elements and avoid mechanical or physical damage that reduces or impairs the component’s ability to resist adverse conditions during service. Tendon components will be rejected for heavy corrosion or pitting, but not for a light coating of rust. Use the protection systems as follows:

Protect the entire length of prestressing steel from the anchor plate to the end of the tendon from corrosion.

Fill the cement grout between the soil and the tube to at least 1/2 in. (13 mm) thick and extend the entire length of the tendon.

not use wood or material harmful to the tendon steel or corrugated plastic tubing as centralizers.

Ensure that the sheath is at least 0.05 in. (1.27 mm) thick. 989 989 989 989 989

prestressing steel in the entire free length. Ensure that the plastic sheath is seamless, hot melt extruded polypropylene shrunk tightly onto the grease. Ensure that the sheath has a coefficient of friction with the steel of less than 0.05 and a wall thickness of at least 0.05 in. (1.27 mm).

0.01 in. (0.25 mm) thick. Minimize the void space between the sheath and the steel by filling visible void spaces with grease and sealing the bottom to keep the grout out.

Protect the area immediately behind the stressing anchorage.

the sleeve.

pipe sleeve.

end of the pipe sleeve with grout. Keep the pipe sleeve free of harmful material until the upper portion of the pipe sleeve and anchor head is filled with grout.

expansion grout.

Encase the anchorage system head at each lift into a corrosion protective system before proceeding to the next lift. Install the protective system for each lift within 30 days after installing the anchors for that lift. Ensure that the anchorage system has a cover of at least 3 in. (75 mm) once the wall face is placed.

617.3Construction Requirements

617.3.01 Personnel

The Contractor and Subcontractor shall be experienced in designing or constructing permanently anchored walls. Provide at least one Registered Professional Engineer licensed to perform work in the State of Georgia and a supervising Engineer for the Project with at least 5 years of experience in constructing permanently anchored walls. Furnish verification of these qualifications to the Engineer before beginning operations.

The Design Engineer shall: • Be registered as a Professional Engineer in the State of Georgia • Have considerable knowledge and experience designing and constructing anchored walls • Be available at any time during the Contract to discuss the design of the walls with the Department

Retain the services of a second registered Professional Engineer licensed to perform work in the state of Georgia and prequalified by the Department. The Engineer shall operate independently from the Professional Engineer of Subsection 617.3.01.A, Contractor Qualifications. This Engineer will independently check the design calculations and Plan details for the permanent anchored walls before submitting them to the Department for review. 990 990 990 990 990

617.3.02 Equipment

Use anchorage and hardware suitable for the type of anchor tendon used. Ensure that anchorage and hardware are capable of the following: • Developing 95 percent of the guaranteed specified minimum ultimate tensile strength of the tendon, when tested in the unbonded state and without failure of the tendon • Holding a load of prestressing steel that produces a stress of at least 95 percent of the guaranteed specified minimum ultimate tensile strength of the prestressing steel, without exceeding the anticipated set and without causing anchorage or prestressing steel failure • Lifting-off, detensioning, or retensioning a tendon before secondary grouting to fill voids at the top of the pipe sleeve

Use anchor nuts and plates for bars that have complementary spherical shapes at the contact areas. 617.3.03 Preparation Before beginning the work, survey the condition of the adjoining properties. Keep records and photograph settlement or cracking of adjacent structures that may become the subject of possible damage claims. Deliver the report to the

Department before beginning work at the site.

Obtain a Foundation Investigation Report from the Geotechnical Engineering Bureau of the Department to assist in

evaluating existing conditions for design and construction.

617.3.04 Fabrication

Fabricate the tendons according to the approved details.

Tendons will be rejected for damage such as abrasions, cuts, nicks, welds, weld splatters, or heavy corrosion

and pitting.

Replace the tendons at the Contractor’s expense for material replacements or time delays.

617.3.05 Construction

The design criteria for a proposed alternate or design include:

including interims.

Ensure that the facing structural thickness is at least 12 in. (300 mm). Perform architectural facing treatment

as shown on the Department drawings.

Extend the facing 2 ft. (600 mm) below the gutterline or, if applicable, the ground line adjacent to the wall

unless otherwise indicated on the plans. 991991991991991

Use steel or concrete soldier piles with a steel yield strength at least 36,000 psi (248 MPa). Ensure that the

concrete has a 28-day strength of at least 3,000 psi (20 MPa).

drop inlet using pipe or free drainage through traffic barriers or other obstructions.

Ensure that holes through traffic barriers or facing are no higher than 3 in. (75 mm ) above the gutterline or

ground line.

signs, or other appendage on top or adjacent to the wall. Figure 1, Figure 2, and Figure 3 indicate loading

conditions for soldier piles, lagging, and anchors at critical stages of construction.

FIGURE 1

Load case 1

Soldier piles and lagging cantilevered

during excavation for top row of anchors

Surcharge +

H

Temporary bottom of excavation

γ a kp*

γ a k A *

γ

b k A *

γ H k A *

γ (H+a) k A * a

b

γ (H+a) kp*

γ

(H+b) kp*

+ Design pressure diagram shall include the effect of surcharge loading

* NOTE: T he above diagrams apply for cohesionless soils. For cohesive soils the effect of cohesion may be considered.

Where lagging is in place, active earth pressure acts over the entire w all surface. Below lagging, active earth pressure acts only on the

soldier pile width and passive earth pressure is generated as follows:

A) In sands and saprolitic soils (w ith blow counts of 10 or greater) passive pressure is generated over 3 times the soldier pile width.

B) In clays, non-saprolitic silts, and saprolitic soils (with blow counts of 10 or less) passive pressure is generated over the width of the

soldier pile.

Vertical component of anchor force must be resisted by embedded length of soldier piles below assumed excavation.

γ

is the soil unit weight in pounds per cubic foot. 992992992992992

FIGURE 2

Anchor force

F inal grade

y b kP * y (H + b) k A*

y H k A *

b

H

65 y H k A

Surcharge +

* See “N OTE” Figure 1.

+ Design pressure diagram shall include the effect of surcharge loading.

K A = C oefficient of active earth pressure

K P = C oefficient of passive earth pressure

g = Soil density

Load Case II

Intermediate Excavations for Subsequent Anchor Installations 993993993993993

FIGURE 3

guaranteed ultimate tensile strength of the tendon.

Lb = P/(3.1416) (d) (tw)

where

Lb= Bond length (not less than 10 ft. [3 m])

P= Design load for the anchor

d= Diameter of the drill hole

tw= Bond stress in the interface between the rock and grout

When determining the bond stress, consider the critical nature of the anchor application, rock property

variations, and installation procedures.

Anchor force

Final grade

γ

b kP *

γ

(H + b) k A*

γ

H k A*

b

H

65

γ

H k A

Surcharge +

* See “NOTE” Figure 1.

+ Design pressure diagram shall include the effect of surcharge loading.

K A = Coefficient of active earth pressure

K P = Coefficient of passive earth pressure

g = Soil density

Load Case II

Final Constructed Condition Assuming Excavation for Drainage Facilities in

Bottom of

lagging

Excavation for roadway

drainage facilities

a

b

front of Wall 994994994994994

length is started at least 5 ft. (1.5 m) beyond the failure plane. Consider the following in the analysis:

• Type of foundation, nearness, and susceptibility to movement of adjacent buildings

(see Figure 4).

• Interaction of anchor groups when the anchor center-to-center spacing is less than or equal to 6 times the

bulb diameter

FIGURE 4

ultimate tensile strength of the tendon.

estimates. Verify the final anchor capacity by field testing each anchor.

Professional Engineer of Subsection 617.3.01.B.

Have this Engineer independently check the design calculations and Plan details of the permanent anchored

walls before submitting them to the Department for review. 995995995995995

The Department may install devices to monitor ground movements and load transfers during and after

construction. The Department will schedule installation to minimize interference with the Contractor’s operations.

Cooperate with the instrumentation installers. Anticipate delays of two to four hours per instrumented anchor.

Although the Instrumentation Specialist maintains the instruments, assume responsibility for damage to the

instruments, connections, or readouts from operations. Replace and install damaged equipment at the

Department’s approval and at the Contractor’s expense.

tendon fitted with a stressing anchorage at one end and a way to transfer force to the grout and rock on the

other end.

stressed to a specified force. The basic components of a prestressed rock anchor are as listed below:

of these two parts:

• Bond length (socket)—the portion of the anchor that transmits the force to the surrounding rock

• Free length (stressing length)—the portion of the anchor free to elongate elastically during stressing

under load.

induced force to the surrounding grout or rock. Deformed bars and strand tendons do not have fixed

anchorages since the anchor load is transferred to the grout by bond.

through the drill casing or rods.

Install the rock anchors as follows:

applicable, and to review the geotechnical data available for the project.

using water in the drilling operation, dispose of the water to minimize wall erosion.

Repair water erosion damage to the site at no cost to the Department.

is at least 3 in (75 mm) if no pressure grouting is used.

Pressure grouting is grouting with a pressure greater than 60 psi (415 kPa).

design Plans. Do not allow holes to deviate from a straight line by more than 1 to 2 in. (25 to 50 mm)

in 10 ft. (3 m).

Do not allow holes to extend outside the Right-of-Way limits. Thoroughly clean holes of rock dust, rock chips,

grease, or other material before inserting the tendon.

is not damaged during handling or installation. 996996996996996

Degrease the bond length of strands or wires before installing by using Acetone, MEK, or MIBK. Do not leave

residue on the tendon. Use other substances only after the Department’s approval. Include the costs of

cleaning tendons in the price bid for Contract Items.

elements to achieve proper grout coverage.

NOTE: Do not use anchors to ground electric equipment and do not subject anchor tendons to

sharp bends.

use wood spacers or other material harmful to the tendon steel or sheathing.

Equip the grout pump nozzle with a grout pressure gauge capable of measuring pressure of at least

150 psi, (10 kPa) or twice the actual pressure used.

select the proportions based on prior documented experience with similar materials and equipment under

comparable field conditions.

of 0.45. Do not leave grout in the mixer longer than 45 minutes.

Only fill voids at the top of the free length with grout after final lock-off.

Keep the mouth of the hole clean after grouting. Record the following data in a Project field book during the

grouting operation:

• Type of mixer

• Water-cement ratio

• Type of additives

• Grout pressure

• Type cement

• Test sample strengths (before stressing)

• Volume of grout placed in bond and free lengths

pressure of 60 psi (415 kPa) or less, always perform a water tightness test.

Perform the test as follows:

hydrostatic head as measured at the top of the hole.

per minute (12 mL per 25 mm diameter per meter of depth per minute), consolidate grout, re-drill, and

retest the hole. If the second water tightness test fails, repeat the entire process.

inter-hole connections.

the grout has initially set. 997997997997997

After the Engineer accepts an anchor, the portion of the anchored tendon protruding over the anchor may be cut if

it is not required for use in retesting. Cut the tendon according to the tendon manufacturer’s recommendations as

approved by the Engineer. Do not damage the tendon anchor.

If the anchors fail during performance tests or proof tests, modify the design or construction tests and procedures.

The design is subject to Department review. These modifications may include:

• Reducing the anchor design load by increasing the number of anchors

• Increasing the grout pressure

• Requiring post-grouting or increasing the bond length

Modify the design or construction procedures, install the redesigned anchors in the wall, and test as previously

defined at no cost to the Department.

Anchors that fail the performance or proof tests may be incorporated in the wall. Propose a reduced design load

and retest as noted above. The Department will determine acceptance of such anchors.

A prestressed soil anchor is a high-strength steel tendon fitted with a stressing anchor at one end and an anchor

device that transfers force to the soil on the other end. These anchors are used in clay, silt, sand, or gravel and are

inserted in a prepared hole that is drilled or driven into the ground.

The following are the two soil anchors considered for use:

• Friction type—rely on friction between the drilled borehole walls

• Anchor grout—rely on an enlarged pressure-grouted bulb or an underreamed bulb to provide resistance to

pull-out

Test the soil anchors after placing the anchor grout and after the curing period. The basic components of the soil

anchor are identical to the rock anchor as described previously.

For installation, see Subsection 617.3.05.D, Rock Anchor Installation, except water tightness tests are

not required.

Test and stress soil anchors according to 617.3.06.A , Anchor Testing and Stressing except that 15% of the

anchors remaining after the initial testing shall be performance tested.

See Subsection 617.3.05.E, Cutting of Tendon Protrusions.

See Subsection 617.3.05.F, Redesign.

617.3.06 Quality Acceptance

Perform testing and stressing according to this subsection.

Test each anchor to ensure that the maximum test load does not exceed 80 percent of the guaranteed ultimate

tensile strength of the tendon.

Performance test the first 2 anchors installed of each design load capacity and 5 to 10 percent of the remaining

anchors (the Engineer will choose the locations). Proof test the remaining anchors.

998998998998998

Cycle Load

1 AL (AL = Alignment Load)

0.25P

AL

2 0.25P

0.50P

AL

3 0.25P

0.50P

0.75P

AL

4 0.25P

0.50P

0.75P

1.00P

AL

5 0.25P

0.50P

0.75P

1.00P

1.25P

A L

6 0.25P

0.50P

0.75P

1.00P

1.25P

1.50P (Test conditions—hold for at least 50 mins.)

independent fixed reference point.

999999999999999

Submit the loading and unloading rates (tons [megagrams] per minute) for approval. Each load must be

applied in less than 30 seconds after starting the jack pump.

the anchor movement (total movement) referenced to a fixed point at 30 seconds, 1, 2, 3, 4, 5, 6, 10, 15, 20,

25, 30, 40, and 50 minutes.

Begin the observation time when the jack begins to load the anchor from 1.25P to the test load.

250 minutes and record the movements at 60, 75, 90, 100, 120, 150, 180, 210, 240, 270, and 300 minutes.

acceptable if:

• The total movement obtained exceeds 80 percent of the theoretical elastic elongation of the free length

and is less than the theoretical elastic elongation of the total of the free length plus 50 percent of the

bond length.

• The creep movement does not exceed 0.08 in. (2.00 mm) during 5- to 50-minute time increments

regardless of tendon length and load.

• If held for an additional 250 minutes, creep movement does not exceed 0.08 in (2.00 mm) from the

30-minute to the 300-minute time increment regardless of tendon length and load.

• AL

• 0.25P

• 0.50P

• 0.75P

• 1.00P

• 1.25P

• 1.50P (Test conditions—hold for at least 10 minutes)

independent fixed reference point.

performance test.

If required by the Engineer, monitor the jack load with the production gauge and load cell that were

calibrated as a set.

seating losses.

Record the anchor movement (total movement) referenced to a fixed point at 30 seconds and 1, 2, 3, 4, 5,

6, and 10 minutes.

Begin the observation time when the jack begins to load the anchor from 1.25P to the test load.

load for an additional 40 minutes. Record the movements at 15, 20, 25, 30, 40, and 50 minutes. 10001000100010001000

acceptable if:

• The total movement obtained exceeds 80 percent of the theoretical elastic elongation of the free

length and is less than the theoretical elastic elongation of the total of the free length plus 50 percent

of the bond length.

• The creep movement does not exceed 0.04 in. (1.00 mm) during the 1-minute to 10-minute increment

regardless of tendon length and load.

• If held for an additional 40 minutes, creep movement does not exceed 0.08 in. (2.00 mm) during the

5- to 50-minute increment regardless of tendon length and load.

greater than 100 psi (690 kPa). Ensure that it has a non-parallax dial.

50 psi (345 kPa). Ensure that they have a non-parallax dial.

uneven loading.

Check the pressure gauge and load cell calibration every week (or when erratic results are found) against

a test gauge that is kept onsite for this purpose. Have the Department’s Inspector witness these

calibration checks. Perform installation, testing, and stressing in the Department Inspector’s presence.

anchorage and before removing the jack.

anchorage and make another lift-off reading.

After performing 5 additional lift-off tests, perform lift-off tests randomly. The total number of tests will be

performed on no more than 10 percent of the remaining anchors.

617.3.07 Contractor Warranty and Maintenance

General Provisions 101 through 150.

617.4Measurement

Permanently Anchored Walls are not measured separately for payment.

617.4.01 Limits

In cases where additional wall area is required due to unforeseen foundation conditions or other reasons as approved

by the Engineer, or, if the wall area is decreased, measurements based on plan dimensions will be used to adjust the

Lump Sum Price Bid referenced under Payment. 10011001100110011001

617.5Payment

Payment for this work is made per Lump Sum. Payment includes costs for concrete, reinforcing steel, excavation,

backfill, lagging, piles, anchors, labor, design, and other materials and equipment. Payment also includes grouting,

drilling holes, post-tensioning, performing and evaluating tests, and submitting records of tests, tools, and other items

to complete the work.

Payment will be made under:

Item 617 Permanent anchored wall, wall no.___ Per lump sum

617.5.01 Adjustments

Additional wall area required because of unforeseen foundation conditions or other reasons that are approved by the

Engineer, will be paid for by increasing the Lump Sum Price Bid. The increase in wall area will be multiplied by an

adjustment price of $45 per square foot ($485 per square meter).

If the wall area is decreased, the Lump Sum Price Bid is adjusted proportionally to the decrease in wall area. The

adjustment price is the Lump Sum Price Bid divided by the original plan area of the wall.

No additional compensation will be made for additional material, equipment, design, or other items to comply with the

project specifications as a result of the Department’s review of an alternate design. If based on a redesigned wall, the

bid price includes costs to comply with the requirements of this specification.

No additional compensation will be made for subsequent changes or deviations from the approved plan for additional

material, labor, or equipment that may be required to comply with the acceptance criteria of this specification.. 1002 1002 1002 1002 1002