Retained Earth Installation Manual

8/13/2019 Retained Earth Installation Manual

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INSTALLATIONMANUALRETAINED EARTH WALLS WITH

CONCRETE FACING PANELS


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THE REINFORCED EARTH COMPANY

Installation Manual For Retained Earth Walls

Table of Contents

Section Title Page

1.0 PREFACE..... ......................... .......................... ......................... ......................... ................................ .. 3

2.0 LIMITATIONS.......................................... ......................... .......................... ................................ .......... 3

3.0 INTRODUCTION.................................. ......................... ......................... .......................... .................... 3

3.1 Purpose.......................... ......................... .......................... ......................... ............................. 4

3.2 Responsibility ...................... ......................... .......................... ......................... ........................ 4

3.3 Plans, Specifications, Shop Drawings .......................... ......................... ......................... .......... 5

3.4 Components ........................ ......................... ......................... .......................... ........................ 5

3.4.1 Concrete Leveling Pad ....................... ......................... .......................... ...................... 5

3.4.2 Precast Concrete Facing Panels.............................. .......................... ......................... . 5

3.4.3 Joint Materials...................... .......................... ......................... ......................... ........... 6

3.4.4 Soil Reinforcing Mesh......................... ......................... ......................... ....................... 6

3.4.5 Select Granular Backfill ...................... ......................... ......................... ....................... 8

3.5 Materials and Services Provided by The Reinforced Earth Company................................. ....... 8

3.6 Tools, Equipment and Materials Supplied by Contractor................. .......................... ................ 8

3.7 Scope of Work Performed by Contractor...................... ......................... .......................... ......... 9

4.0 HANDLING RETAINED EARTH COMPONENTS .......................... ......................... ......................... ..... 9

4.1 Delivery of Precast Panels ......................... ......................... .......................... ......................... .. 9

4.2 Unloading of Panels............. .......................... ......................... ......................... ...................... 10

4.3 Soil Reinforcing Bar Mats....................... ......................... .......................... ......................... .... 10

4.4 Other Components ....................... ......................... ......................... .......................... ............. 10

4.5 Verification....................... ......................... ......................... ......................... ........................... 10

5.0 CONSTRUCTION SEQUENCE AND PROCEDURES ....................... ......................... ........................ 10

5.1 Site Preparation...... .......................... ......................... ......................... .......................... ......... 11

5.2 Leveling Pad.................... ......................... ......................... .......................... .......................... 11

5.3 Wall Baseline........... ......................... ......................... ......................... .......................... ......... 11

5.4 General Safety.................................. ......................... ......................... ......................... .......... 11

5.5 Initial Course of Panels .......................... ......................... ......................... ......................... ..... 11

5.6 Installation of Joint Materials....................... ......................... ......................... ......................... 135.7 Placement and Compaction of Backfill ......................... ......................... ......................... ........ 13

5.8 Installation of Soil Reinforcing Bar Mats ....................... ......................... .......................... ....... 14

5.9 Continuation of Construction.......................... .......................... ......................... ..................... 15

5.10 Completion of Top Wall.......................... ......................... ......................... .......................... .... 15

2006 The Reinforced Earth Company. All rights reserved.


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1.0 PREFACE

This Installation Manual has been prepared as a gen-eral guide for the construction of Retained Earthwalls. No warranty, expressed or implied, is made.

The contents of this manual should be reviewed by the

Contractor and the field personnel responsible forconstruction prior to delivery of Retained Earth wallmaterials and components.

The Reinforced Earth Company will provide a TechnicalAdvisor to assist the Contractor in developingconstruction procedures consistent with both thetechnical and aesthetic requirements of the project.Should any conflict arise between the ContractDrawings, Specifications, Special Provisions orContract Documents and the contents of this manual orany oral or written instructions from the Technical

Advisor, the requirements of the Contract Drawings,

Specifications, Special Provisions and ContractDocuments shall prevail, unless authorized by theEngineer in writing.

It is the Contractors responsibility to ensure that allconstruction work associated with Retained Earthstructures is carried out in accordance with theappropriate Contract Drawings, Specifications, SpecialProvisions and Contract Documents. The guidelinescontained in this manual should not be interpreted asrelieving the Contractor of any of his contractualobligations and responsibilities.

2.0 LIMITATIONS

The following attached document(s) (hereinafterreferred to as Documents) are the property of TheReinforced Earth Company and contain proprietaryinformation regarding The Reinforced Earth Companyspatented mechanically stabilized earth system knownas Retained Earth.

oShop Drawings and Design Calculations

Retained Earth Installation Manual

o Standard Specifications for Retained Earth

These Documents have been made available solely inconnection with the Retained Earth project described inthe Documents, and for no other purpose.

Information in any of the Documents is not to be usedto design, fabricate, manufacture, assemble, construct,produce or install or otherwise use any elements, formsor special equipment (whether patented or not) uniqueto Retained Earth, or for any other purpose without theprior express written consent of The Reinforced EarthCompany.

The Documents and the information contained thereinmust not be copied, disclosed or distributed in any

manner, in whole or in part, to any third party withoutthe prior express written consent of The ReinforcedEarth Company.

Receipt of any or all of the Documents carries noentitlement to any property right in either the documentsor the information contained therein.

Retained Earth structures are designed by TheReinforced Earth Company based entirely on:

The internal stability of the reinforced soil masscomprising the Retained Earth structure based onthe design assumptions and material propertiesnoted on all The Reinforced Earth Companysdrawings and calculations relevant to thestructure, external loads, surcharges andgeometry, provided by or on behalf of the Owner.

The layout and geometry of the reinforced soilstructures based on survey information, plans,

drawings and other information provided by or onbehalf of the Owner.

The Project Specifications and all other relevantstandards required in terms of Contract Drawings,Specifications, Special Provisions or ContractDocuments. The Reinforced Earth Company isresponsible only for the internal design of theRetained Earth structure. External stabilityconsiderations, including global slope stability,bearing capacity, settlement, sliding, overturningand drainage under both static and seismic loading,are the responsibility of the Owner. The ReinforcedEarth Company warrants the internal stability of the

structure only, based on the completeness andaccuracy of the information provided by or onbehalf of the Owner, and used or relied upon indesigning the Retained Earth structure.

3.0 INTRODUCTION

Retained Earth is a composite material created by theinteraction between soil reinforcing elements and selectgranular backfill. Reinforced soil structures, such asRetained Earth, are very different from conventionalearth-retaining structures since they make use of anentirely different method of support.

Conventional retaining structures may be classified as

externally stabilized systems since they use an externalstructural wall against which stabilizing forces aremobilized. Reinforced soil structures are termedinternally stabilized systems because the soilreinforcing elements are installed within, and extendbeyond, the potential failure plane. With an internallystabilized system, shear transfer to mobilize the tensilecapacity of closely spaced reinforcing elementseliminates the need for a structural wall and, instead,substitutes a composite material, comprising reinforcing

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elements and granular soil, as the principal structuralunit. A facing is needed on an internally stabilizedsystem, but its primary functions are to prevent localraveling and provide an architectural finish rather thanprimary structural support.

In general, soils can only support compressive and

shear stresses. In a reinforced soil structure the primarypurpose of horizontal reinforcing elements is to resistthe lateral tensile stresses induced in the soil as itdeforms (i.e., experiences lateral tensile strains) inresponse to applied loads. The reinforcing action isgreatest when the reinforcement is oriented parallel tothe direction of the tensile strains; in addition, for thereinforcing action to be most effective, there should beno slip (i.e., relative movement) between the reinforcingelements and the surrounding soil. The maincomponents of a Retained Earth structure areillustrated in Figure 1.

3.1 Purpose

This Installation Manual is intended to provide theOwner, Contractor, Engineer and inspection personnelwith the guidelines necessary to observe and monitorthe construction of Retained Earth structures forcompliance with approved shop drawings, projectspecifications, special provisions, and all other relevantcontract documents. The primary purpose is toestablish minimum standards of workmanship andconstruction tolerances.

The contents of this manual are limited to generalguidelines which may be applicable for most routineRetained Earth construction. Projects involving special

applications or unusual conditions are addressedseparately during the field technical assistanceprogram.

3.2 Responsibility

It is the Contractors responsibility to ensure that allRetained Earth construction is carried out in strictaccordance with the approved shop drawings, projectspecifications, special provisions, and all other relevantcontract documents. This Installation Manual is only

intended to aid the Contractor in complying with theappropriate project requirements.

None of the information in this manual is intended torelieve the Contractor of his obligation andresponsibility in complying with all applicable safetystandards and procedures and quality control andassurance programs associated with the project. TheContractor and Owner are responsible for verifying thatthe Contractors field personnel are in possession ofand fully familiar with the construction proceduresoutlined in this manual.

Job-site Technical Advisors from The Reinforced Earth

Company are available to assist the Contractor withmaterials scheduling and coordination, and provide fieldassistance on appropriate construction procedures forRetained Earth structures in compliance with therecommendations contained in this manual.

In general, Technical Advisors are not available toassist on-site on a full-time basis and are not to be usedas a substitute for the Owners and Contractors qualitycontrol and/or inspection services.

It should also be appreciated that Technical Advisorsfrom The Reinforced Earth Company are notresponsible for enforcing the requirements of the plans,

specifications, special provisions, and contractdocuments. This is the sole responsibility of theEngineer.

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The first number (4) indicates the number oflongitudinal wires in the bar mat. These wiresinclude a loop on one end which is connected tothe clevis loop embeds in the back of the panels.

The next combination of a letter and a number

(W15) denotes the size of the longitudinal wires.The W prefix denotes imperial units and thenumber (15) gives the nominal cross-sectionalarea in hundredths of a square inch. When usingmetric units, the prefix is WM and the numberrefers to the nominal cross-sectional area in mm2.

The designation following the dash (W11)indicates the nominal cross-sectional area of thetransverse wires.

The final number (18) refers to the spacing ininches of the transverse wires; in the metricsystem the spacing is in millimeters. Standardtransverse wire spacing are 6, 12, 18 and 24

inches (or 150, 300, 450 and 600 millimeters).

The spacing of the transverse wires is constant along theentire length of the bar mat, making it easy to determinethe length of bar mats by counting the number of trans-verse wires. The distance, or overhang, from the loopedends to the first transverse wire varies from project to pro-

ject, but will always be the same for any specific project.The typical overhang is 24 inches (600mm). Wire size ischecked in the field using the sizing device supplied.

Dark, heavy horizontal lines on the wall elevations indi-cate changes in bar mat type. Dark, heavy vertical linesindicate changes in the length of the soil reinforcing

mesh. Bar mat lengths are shown below the leveling padon the wall elevations.

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Each longitudinal wire in a bar mat has a welded loop atthe end which is placed between the two legs of aclevis loop embed in the back of the panel. The connec-tion is made using a connector pin which typically ex-tends 3 inches (75mm) beyond the edge of the bar mat.In locations where extra clevis loop embeds have beencast into the panels, but are not needed to connect therequired bar mats, they may be bent flat against theback face of the panel to facilitate use of the correctconnector pin.

Each nominal 5-foot (1.5m) panel will have two bar

mats, requiring two connections. Other reinforced soilsystems which do not use mesh reinforcing elementswill have at least four connections for the same panelsize. Also, some bar mat systems require the insertionof two (partial) connector pins per bar mat; i.e., a totalof four connectors for each standard full-size panel. Thenumber of connections and the ease with which theycan be made are important factors in determining ratesof panel placement.


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3.4.5 Select Granular Backfill

Ideally, the backfill in a reinforced soil structure shouldconsist of well-graded granular material compacted to ahigh density for maximum strength and minimum com-pressibility. The preferred particle size range for rein-

forced soil is a well-drained, well-graded granular mate-rial, providing long-term durability, stability during con-struction and possessing good electrochemical proper-ties. In the typical stress range associated with rein-forced soil structures, well-graded granular materialsbehave elastically, and post-construction movementsassociated with internal yielding are rare. Fine-grainedsoils are normally poorly drained and effective stresstransfer between soil and reinforcement may not beimmediate. Such soils also often exhibit time-dependentbehavior, thereby increasing the risk of post construc-tion movement.

The soil should possess a wide range of grain sizesand contain no more than 15 percent passing the No.200 sieve (74 microns). This criterion represents thepoint at which intergranular contact in the soil skeletonstarts to break down, causing a loss of internal strength.The soil should not be gap-graded as this tends tomake good compaction more difficult and can lead tointernal piping erosion under small hydraulic gradients.

The reinforced soil backfill must meet the specified re-quirements with respect to gradation, shear strength,permeability, and electrochemical properties includingresistivity, pH, organic content and chloride and sulfate

contents. Electrochemical properties are particularlyimportant as they determine the rate at which corrosionof metal reinforcement may occur in the completedstructure.

The responsibility for ensuring that all reinforced soilbackfill meets both the geotechnical and electrochemi-cal requirements specified rests with the Contractor.The Reinforced Earth Company is not responsible forapproving backfill sources or backfill materials.

3.5 Materials and Services Provided by TheReinforced Earth Company

Shop drawings and design calculations for the

Retained Earth structures signed and sealed by aRegistered Professional Engineer.

Precast concrete facing panels.

Soil reinforcing bar mats and connector pins.

Bearing pads, filter cloth and adhesive or foamstrips, as required.

Lifting eyes for handling precast concrete panels.

Delivery of The Reinforced Earth Company- furnished materials to the site (FOB) with two

hours allowed for unloading of each shipment.

Initial on-site technical assistance by a ReinforcedEarth Company Technical Advisor.

Soil reinforcing bar mats, connector pins, filter cloth,

adhesive, HDPE bearing pads, and other special mate-rials provided by The Reinforced Earth Company arebundled and tagged to minimize damage in handlingand unloading and to ease in identification.

All materials must be thoroughly inspected upon deliv-ery to the site and any damaged items must be notedand set aside and The Reinforced Earth Company noti-fied immediately. Materials should be stored to preventdamage, loss or theft. Filter cloth must be stored andprotected from sunlight.

Certificates of compliance with project specifications forall materials are available on request from The

Reinforced Earth Company. However, it is the responsi-bility of the Contractor to ensure that all materials deliv-ered to the job site are consistent with the shippingdocuments and the appropriate project specifications.

Any discrepancies must be reported immediately to TheReinforced Earth Company.

It is the responsibility of the Contractor to continuallyupdate The Reinforced Earth Company with respect toscheduling of future material deliveries to avoid con-struction delays.

3.6 Tools, Equipment and Materials Supplied byContractor

The construction of Retained Earth walls is relativelystraightforward and repetitive and does not generallyrequire specialized labor or equipment.

Hand Tools

2-foot and 4-foot long carpenter levels.

Claw hammers.

Chalk line and chalk.

Caulking gun for 29-ounce tubes of adhesive.

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Wrenches for clamps (2 ea.)

16-d nails.

30-inch or 36-inch nail bars (2 ea.)

Sledgehammer.

Hand-operated or power-operated saws.

Gloves for handling wire mesh bar mats andconnector pins.

Lifting and Unloading

Panel lifting eyes (supplied by The ReinforcedEarth Company).

Spacing tools (supplied by The Reinforced EarthCompany).

Non-staining dunnage for storage of precastconcrete panels.

Two approximately 22-foot (7m) long web slingsfor unloading panels.

Shackles (3 ea.) and two approximately 4-foot long(1.2m) cable slings.

Construction

2-inch x 4-inch wooden clamps (No. required = 2.5times number of panel columns comprising 4 inchlong 2-inch x 4-inch (2 ea.) and one 14-inch(350mm) long 1/2-inch diameter coil rod with twonuts and two washers.

2-inch x 4-inch wooden braces by 8-foot (2.5m)long (No. required = 0.5 times number of panel

columns).

2-inch x 4-inch wooden panel thickness spacers(No. required = 0.5 times number of panelcolumns).

2-inch x 4-inch wooden stakes or steel nail pins tosupport bracing (No. required = 0.5 times numberof panel columns).

Wooden wedges (No. required = 4 times numberof panel columns).

Equipment

Handling of Panels: A small hydraulic crane or boom

truck to lift and place precast concrete facing panels.A standard 6-inch (150mm) thick, 5-foot (1.5m)square panel weighs about 1900 lb (860kg) and anominal 10-foot x 5-foot (3.05m x 1.5m) rectangularpanel weighs 3750 lb (1700kg).

Placement of Backfill: Depending on access andworking space, this can be done using dump trucks,front-end loaders, scrapers, bulldozers or graders. Awater truck is used to bring the water content of thebackfill up to desired range for compaction.

Compaction of Backfill: Two types of compactionequipment are needed for Retained Earth wall con-struction. Large smooth-drum vibratory rollers areused for the compaction of most Retained Earthbackfills at distances of more than 3 feet (1m) behindthe panels. In fine-grained, uniformly graded sand,

static equipment is likely to be more effective. Within3 feet (1m) of facing panels, compaction is usuallyachieved using lightweight, walk-behind vibratory roll-ers or plate compactors to avoid the buildup of largetensions in the soil reinforcement/panel connectionsand misalignment of facing panels.

3.7 Scope of Work Performed by Contractor

Site preparation including excavation, temporaryshoring (if required), dewatering, foundationtreatment and installation of all drainage systemsas required.

Layout of wall geometry with respect to line and

level. The contract plans, not the Retained Earthapproved shop drawings, must be used for thelayout information.

Construction of the unreinforced concrete levelingpad in accordance with the steps and grades givenon the approved shop drawings for the RetainedEarth walls.

Construction of the Retained Earth structurescomprising the placement and erection of precastconcrete facing panels, installation of jointmaterials including bearing pads and filter cloth,placement and connection of soil reinforcingbar mats, and placement and compaction of thereinforced soil backfill.

Placement of any precast or cast-in-place concretecoping, traffic impact barrier, or any othersecondary concrete components, as required.

4.0 HANDLING RETAINED EARTH COMPONENTS

Retained Earth components are specially designed andfabricated for a specific project, i.e., they are not off-the-shelf materials. Consequently, it is imperative that thematerials, especially precast concrete panels and soilreinforcing bar mats, are handled correctly so that theneed for expensive and time-consuming replacement

materials is kept to a minimum. It is the responsibility ofthe Contractor to ensure that all Retained Earth compo-nents are free from any damage that might render themunacceptable for use in construction. The ReinforcedEarth Company will not be responsible for any replace-ment costs, time delays, lost production, etc., associ-ated with damage to any components sustained subse-quent to delivery and acceptance by the Contractor.

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4.1 Delivery of Precast Panels

To ensure timely delivery, it is imperative that the Con-tractor and The Reinforced Earth Company agree on apanel delivery schedule for the project. This is importantbecause, while many of the panels have the same over-all geometry, there are differences with respect to the

number of soil reinforcing/panel connector embeds,panel reinforcement and dimensions, especially in thecase of partial panels at the top of the wall.

Panels are not available for shipping immediately uponcasting since a minimum concrete strength (typicallyaround 85 percent of the specified 28-day strength)must be reached to prevent cracking during loading,transportation and unloading. In many cases, theOwners inspection service will not release panels foruse in construction until the appropriate concrete cylin-der strengths meet the specified 28-day strength.

Precast concrete panels are shipped to the site on flat-

bed trailers. Typical truckloads comprise four or fivestacks, each containing four or five panels, for a totalpanel area of approximately 600 square feet (55m2).Panels are stacked finished face down and care mustbe taken during unloading and subsequent moving ofpanels to avoid damaging the finish.

4.2 Unloading o f Panels

Unloading of panels is usually done either at a centrallocation for the entire project or as close as practical tothe actual wall site. When unloaded at the wall site, thepanels may either be placed directly into the wall orstored temporarily adjacent to the wall. Placing the pan-

els directly into the wall may require additional unload-ing time and extra costs; the standard unloading time isnormally two hours per truck. Stacks of panels must bestored on a flat, firm surface using non-staining dun-nage. Stacks of panels should be unloaded using eithera crane with two-web slings or a forklift with paddedforks to protect the panel finish. Any damaged panelson the flatbed trailer should be brought to the attentionof the driver and recorded on the delivery ticket.

If the panels are to be placed directly into the wall, thenspecial lifting eyes must be attached to the lifting em-beds in the top edge of the panel to lift and handle indi-vidual panels. Both lifting embeds must be used in lift-

ing and handling panels. All dunnage is the property ofThe Reinforced Earth Company and should be madeavailable for pick-up and reuse.

4.3 Soil Reinforc ing Bar Mats

The soil reinforcing elements for Retained Earth walls com-prise relatively flexible welded wire bar mats. Each wall willrequire several types of bar mats with variations in overalllength, number of longitudinal wires, spacing of transversewires, and wire sizes. The bar mats are delivered in taggedbundles on flatbed trailers. Bar mat lengths typically rangefrom 8 feet (2.5m) to 30 feet (9m), but may be longer.

The bundles may be unloaded using a forklift or slings;the use of a spreader bar is recommended to avoiddamage. Bar mat bundles may be stored directly on theground surface but the use of dunnage will greatly facili-tate future handling and minimize the risk of damage.

The Contractor is responsible for the proper storage

and handling of the bar mats after delivery. In particular,the Contractor must exercise care to ensure that eachbar mat is placed in the proper location in the wall asindicated on the approved shop drawings.

4.4 Other Components

Filter fabric, adhesive, HDPE bearing pads, spacingtools, lifting eyes and other secondary components arenormally shipped separately by common carrier or, insome instances, may be delivered with the first truck-load of panels. All these materials should be storedaway from direct sunlight. Bearing pads and cardboardtubes of adhesive are shipped in cardboard boxes and

must remain dry.

4.5 Verification

All material quantities must be verified by the Contrac-tor at the time of delivery and any discrepancies re-ported to The Reinforced Earth Company within 48hours of delivery. The Reinforced Earth Company willnot be responsible for any costs, delays, etc., associ-ated with the Contractors failure to report discrepanciesin material quantities within 48 hours of delivery.

5.0 CONSTRUCTION SEQUENCE ANDPROEDURES

The construction sequence for Retained Earth struc-tures is straightforward and repetitive. The principalsteps in the construction procedure are summarized asfollows:

Preparation of the area to be occupied by thereinforced soil structure.

Form and cast unreinforced concrete levelingpad.

Install the bottom course of precast concretefacing panels and external bracing.

Place filter cloth over joints between individualpanels.

Place and compact initial lifts of backfill up to thelevel of the bottom layer of soil reinforcingbar mats.

Install and connect bottom layer of bar mats tofacing panels.

Place and compact subsequent lifts of backfill upto the top of the smaller panels in the bottomcourse.

Remove bottom wooden clamps.

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Set batter on panels above the smaller bottompanels using spacers in the wooden clamps.

Place filter cloth over joints between individualpanels.

Place and compact subsequent lifts of backfill up

to the level of the second layer of soil reinforcingbar mats.

Install and connect second layer of bar mats tofacing panels.

Place and compact subsequent lifts of backfill upto the top of the larger (full-size) panels in thebottom course.

Remove external bracing.

Place second course of precast concrete facingpanels.

Repeat the sequence of backfilling and compactingin lifts, placing and connecting bar mats, andinstalling panels until the top of the wall is reached.

Install top-of-wall coping, traffic impact barriersor other precast or cast-in-place concrete walltreatments.

5.1 Site Preparation

The area to be occupied by the Retained Earth struc-ture must be excavated (or backfilled) to the elevationsshown on the Contract Drawings over the length andwidth of the wall sections to be built. Proof-rolling of thefoundation sub-grade, as required by the project specifi-cations, is important in identifying areas of unsuitable

foundation soils that may require treatment prior to wallconstruction. The presence of any areas of potentiallyunsuitable foundation soils should be documented andsubmitted to the Engineer who is responsible for decid-ing what, if any, remedial measures may be necessary.

Any drainage systems required between the reinforcedsoil mass and the foundation soils or the soil to be re-tained by the reinforced soil structure should be in-stalled as required by the Contract Drawings and Speci-fications. Since these systems are external to the rein-forced soil mass, they are the responsibility of the Engi-neer, not The Reinforced Earth Company.

Excavation for the leveling pad may be neat-lined, butonly for the depth of the pad. A minimum of 12 inches(300mm) from the outside face of the wall should beexcavated to the same grade as the top of the levelingpad. This is needed for the insertion of wood wedgesunder the facing panels during placement of the bottomcourse of panels.

5.2 Leveling Pad

Form and pour the leveling pad using concrete with anominal 28-day strength of not less than 2500 psi (17.2

MN/m2). The nominal dimensions of the leveling padare 12 inches (300mm) wide and 6 inches (150mm)deep. The leveling pad must be constructed within atolerance +1/4 inch (+6mm). The leveling pad concretemust be allowed to cure for at least 12 hours prior tobeginning panel erection.

5.3 Wall Baseline

The first step in the erection of the baseline is to estab-lish the starting point. If a working point is shown on theapproved shop drawings, or if the new wall matches anexisting wall, this would be the starting point. If neitherof these is the case, then erection should begin on theleveling pad at the lowest elevation. Face-of-wall lineshould be established from the Contract Drawings andsurvey points marked on the leveling pad. All End Wall,Begin Wall, PC, PI, PT, bends, corners, vertical slip

joints and other significant locations should be marked.Points along a curve or radius should be established atregular intervals to ensure proper panel placement andalignment. Also, intermediate points (at 50-foot centers)should be established to check on overall length. Oncethese points are correctly marked on the leveling pad, achalk line is then snapped between the points. Clearacrylic paint may be sprayed over the chalk line to pro-tect it from rain and foot traffic during erection of thebottom course of panels. Wall alignment references areshown on the approved shop drawings. These are nor-mally the nominal front face of the panels; architecturalfinishes are usually not included in the design as thefront face of the wall. In some cases the wall alignmentmay be referenced to the front face of the coping.

5.4 General SafetyIt is extremely important that everyone in the wall erec-tion crew appreciates that precast concrete panels areheavy and potentially dangerous. Panels can slide offstacks, fall over during installation or may be droppedaccidentally by the lifting equipment. During setting,placement, adjustment and clamping and bracing, it iscritical that anyone within the potential fall zone of anypanel maintain body contact with the panel so as to pro-vide early warning of potential danger. Never walk, runor stand under a hoisted panel and never place anypart of your body between or under panels.

5.5 Initial Course of Panels

Bottom course configurations comprise alternating Aand B30 panels with other A panels on top of the B30panels. Alternatively, the bottom course may consist ofalternating B10 and B15 panels with A panels on top ofthe B15 panels. The installation procedure describedbelow is based on the B15/B45 panel combination.

The first B45 panel (denoted as 1) is placed on the lev-eling pad with its outside (i.e., finished) face flush withthe face-of-wall line. It is then leveled and battered us-

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ing wooden wedges or shims, as necessary. At thisstage, using an equal number of wedges on both theinside and outside faces of a panel is important in en-suring stability.

Panels must be placed at a slight batter towards thebackfill in order to compensate for outward rotation of

the panel consequent upon fill placement and compac-tion. The amount of batter is determined in the fieldbased on the characteristics of the backfill material,bar mat pull-out resistance and panel dimensions.

The panel is then braced externally using a 2-inch x 4-inch clamp and a panel width spacer centered on topof the panel. Next, nail a 2-inch x 4-inch brace to astake or nail pin driven into the ground and to theclamp.

A B15 panel (denoted as 2) is placed next to the first(B45) panel with a 3/4-inch wide vertical joint. The B15

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panel is then leveled, battered towards the backfill andclamped to the B45 panel. The third panel, anotherB45, is placed adjacent to the B15 panel maintaining a3/4-inch wide vertical joint. The panel is then leveled,battered and braced externally.

In preparation for the placement of the fourth panel,loosely install a clamp (2) on top of the B15 panel nextto the previously placed B45 panel. Loosen the clamp

(1) between the B15 panel and the first B45 panel.Place two HDPE bearing pads on top of the B15 panelat the locations indicated on the approved shop draw-ings. Then carefully slide an A panel (4) down betweenthe two B45 panels until it rests firmly on the bearingpads. Final adjustments to this group of panels may nowbe made by snugging the wooden wedges betweenthe panels and the leveling pad.

Tighten the bottom two clamps (1) and (2) in the se-

quence shown, then place and tighten two more clamps(3) and (4) above the first two. The sequence of tighten-ing the clamps is important. If not followed correctly, the

A panel will not slide into position or line up properly. Noother external bracing is needed for the A panel.

Continue the sequence of panel installation, i.e., B15,


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B45 and A, along the length of the wall.

External bracing is only required on the initial course ofpanels to maintain stability of the otherwise unsup-ported panels during placement and compaction of

backfill and connection of the soil reinforcing bar mats.The external bracing must be left in place until its re-moval is necessary for placement of additional backfill.

5.6 Installation of Jo int Materials

HDPE bearing pads shall be positioned as indicated onthe approved shop drawings. Regardless of panel size,only two bearing pad locations shall be used, typicallyat the quarter-span joints. A minimum of two bearingpads must be provided in each horizontal joint. Vertical

joints do not require bearing pads.

Filter cloth, supplied in rolls of the appropriate width, isattached to the panel concrete on each side of all joints.It is not used along the leveling pad. The purpose of thefilter cloth is to maintain the permeability of the facingby allowing water to escape but preventing the loss offine particles from the reinforced backfill. The durabilityof the adhesive is unimportant since its only purpose isto hold the filter cloth in position until it can be confinedby the backfill.

5.7 Placement and Compaction of Backfill

The material to be used in the reinforced volume must

satisfy all the geotechnical and electrochemical require-ments of the project specifications. The backfill must beplaced and compacted to the required density in lifts.The loose thickness of each lift must be consistent with

the compaction equipment being used and the requireddegree of compaction, or as required by the specifica-tions. In no case should the loose-lift thickness exceedone-half the vertical spacing between adjacent soil rein-forcing layers, or 12 inches (300mm), whichever is less.

During the initial stage of wall construction, no backfillshould be placed or compacted against the externallybraced panels, otherwise the panels will be pushed outof alignment. Once the bottom layer of soil reinforcingbar mats has been installed, and one lift of backfill hasbeen placed and compacted over the bar mats, place-ment and compaction of backfill directly against thepanels can proceed.

The backfill should be compacted in layers using largesmooth-drum vibratory rollers except within an approxi-mately 3-foot (1m) wide zone immediately behind thepanels. In this zone, light hand-operated compactionequipment should be used. At the Contractors option,large smooth-drum rollers, operated statically, may beused in this area provided that their use does not causemisalignment of the panels. Compaction should com-prise at least three passes of the equipment; it is notnecessary to do any in-place density tests in this lightly-

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compacted zone. All compaction equipment must beoperated parallel to the wall face, beginning at the backof the reinforced soil mass and working towards thepanels. This aids in locking the bar mats in place beforeloading the panels. At the end of each day, it is impor-tant to protect the backfill from ponding, saturation or

erosion. The backfill must be sloped away from the faceof the wall in order to avoid buildup of water pressuresagainst the panels. In cut situations, it may be neces-sary to remove some panels to allow any water to runout over the face of the wall. Heavy equipment shouldnot be allowed on backfill that is well above the opti-mum water content or saturated because of the likeli-hood of panel movement and misalignment.

5.8 Installation of Soil Reinforcing Bar Mats

Soil reinforcing bar mats are quite heavy. Proper tech-niques must be used when lifting or carrying bar matsby hand. Heavy gloves must be worn when workingwith bar mats. The process of removing bar mats fromgalvanizing baths often leaves sharp spikes or iciclesof zinc which can cause serious injury.

Before installing any bar mats, reference should bemade to the approved shop drawings to ensure that thebar mat matches that required by the Retained Earthdesign in terms of overall length and number and size

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of both longitudinal and transverse wires.

Align the looped end of each longitudinal wire betweena pair of protruding loops of the clevis loop embeds inthe back of the panels. Insert a mesh connector pin of

the appropriate length through all loops. Drive smallwooden wedges between the back of the panel and theouter longitudinal wires and between the embed loopsto remove any slack in the connection. This will alsohold the connector pin in place and prevent it being ac-cidentally displaced during backfill placement and com-paction.

At each soil reinforcement level, the backfill shall beplaced to the level of the panel connectors. Backfillplacement methods near the panels shall assure that

no voids are created directly underneath the soil rein-forcing bar mats.

After connecting the bar mats, placement of the next liftof backfill shall begin 3-5 feet (1-1.5m) from the panels.Backfill material must be carefully placed to avoid twist-ing and sliding of bar mats which could result in pushingor pulling panels out of alignment. Spread the backfillparallel to the wall face, working away from the panelstoward the ends of the bar mats. If backfill placement isbegun near the end of the bar mats, working toward thepanels, then the bar mats are likely to be progressivelypushed forward, leading to misalignment of facing pan-els. This can only be repaired by removing the backfilllift and replacing it in the correct manner.

Once the backfill has been placed and compacted ontop of the first layer of bar mats, backfill may be placedand compacted up to the top of a B15 or B30 panel; atthis point, clamps (1) and (2) may be removed.

The A panel on top of the B15 panel should now bechecked with respect to joint spacing and batter. Theuse of spacers or shims inside the clamps will allow thepanel to be adjusted and maintained at the correct bat-ter. The thickness of each shim should be approxi-mately one-half of the desired panel batter.


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5.9 Continuation of Construction

Backfill may now be placed and compacted up to thelevel of the second layer of soil reinforcing bar mats.Next, place, connect and wedge the bar mats in placeand place and compact the backfill up to the top of theB45 panels. Once both layers of soil reinforcing bar

mats are attached to the full-size bottom panels andbackfilling and compaction are complete, the externalbracing may be removed; no further external bracing isrequired. The batter of the completely backfilled panelsshould be checked at this stage to determine if the ini-tial batter was correct; any adjustments to the amountof batter should be made as subsequent panel coursesare installed.

The second course of panels is now installed. Clamps(3) and (4) are removed and placed on top of adjacentpanels. The HDPE bearing pads are placed in the ap-propriate locations on top of the B45 panels before slid-ing the next A panel into position. Set the vertical jointspacing and clamp the panels in place using the(adjusted, if necessary) thickness of shims in theclamps. Install filter fabric (or foam strips) over all joints,place and compact backfill and install the next layer ofreinforcing bar mats.

The installation sequence for the remainder of the wallfollows that outlined above.

It is important that panels are not installed until theirplacement is needed to continue placement and com-paction of backfill. This means that, except for the bot-tom course of panels (which is braced externally) andthe top-of-wall panels, no panel shall be placed on top

of an existing panel with exposed clevis loop embeds;exposed clevis loop embeds are those that have not yetbeen attached to soil reinforcing bar mats and back-filled.

5.10 Completion of Top o f Wall

Set the top-of-wall panels and clamp them in position.The surface of the backfill may be left lower than normalto facilitate erection of formwork for top-of-wall treat-ments and to provide a measure of additional safety.

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For help or information not included in the InstallationManual, please call one of the following o ffices:


8614 West wood Center Drive

Suite:1100

Vienna, VA 22182