Best Practices for

Design and Construction

of MSE Walls

Robert A. Gladstone, P.E.

Executive Director

Association for Mechanically Stabilized Earth

Geotechnical Consultant Workshop

Ohio Department of Transportation

June 7, 2017

Best Practices for Design and Construction

of MSE Walls

NOT a Best Geotechnical Practice

Best Practices for Design and Construction

of MSE Walls

Common MSE Wall Systems

Segmental Blocks, Steel

or Geosynthetic

Reinforcements

Welded Wire Facings, Steel

or Geosynthetic

Reinforcements

Precast Facing Panels,

Steel or Geosynthetic

Reinforcements

Best Practices for Design and Construction

of MSE Walls

Design Roles and Responsibilities

• MSE Designer

• Civil / Structural

• Geotech• Owner

Service Life Requirements

Aesthetic Requirements

Acceptable Wall Types

Global Stability

Bearing Capacity

Settlement

Acceptable Wall Types

Internal Stability

Detailed facing and

reinforcement design

Construction drawings

Site Grading

Wall Location

DRAINAGE DESIGN

Acceptable Wall Types

Loading

Best Practices for Design and Construction

of MSE Walls

Design Responsibility

• Internal Stability – MSE wall system supplier

• Simple check of sliding and overturning

• Determine eccentricity and applied bearing pressure

• Check reinforcement pullout and rupture

• Design of wall system components

• External Stability – Owner or Consultant

• Owner proposing to build the structure in the specified location

• Therefore, owner is responsible for investigating feasibility

• Includes: global stability, bearing capacity, settlement analysis

Best Practices for Design and Construction

of MSE Walls

Global Stability

Best Practices for Design and Construction

of MSE Walls

Options for Bearing Capacity and Settlement

Best Practices for Design and Construction

of MSE Walls

Specify Requirements in

Contract Drawings

Best Practices for Design and Construction

of MSE Walls

Contract Specifications

Best Practices for Design and Construction

of MSE Walls

Contract Drawings

Best Practices for Design and Construction

of MSE Walls

Design Parameters

• Design usually based on assumed parameters

• These parameters are actually a good choice:

• 34o is maximum value permitted by AASHTO without test data

• 34o is approximately the mobilized shear that will develop

• 34o has been assumed in design for 4 decades

* Foundation soil design parameters

should be clearly defined in the contract documents

Soil Type Unit WeightFriction

Angle

Select Granular fill 125 pcf 34°

Retained Fill 125 pcf 30°

Foundation Soil * ----- 30° *

Best Practices for Design and Construction

of MSE Walls

Coherent Gravity Design

W

Sliding Resistance

Vertical Pressure

E

Facing

Reinforced Soil

Best Practices for Design and

Construction of MSE Walls

Meyerhof Bearing Pressure Distribution

V = e=

V = BEARING PRESSURE

V = SUM OF VERTICAL LOADS

L = REINFORCING STRIP LENGTH

e = ECCENTRICITY OF STRUCTURE

DUE TO APPLIED LOADS

MC = SUM OF MOMENTS ABOUT

CENTER LINE DUE TO APPLIED

LOADS

V

L - 2e

MC

V

Best Practices for Design and Construction

of MSE Walls

Characteristics of the

Coherent Gravity Method

Best Practices for Design and Construction

of MSE Walls

Fabrication / QC and QA

Best Practices for Design and Construction

of MSE Walls

Pre-Construction Meeting

• Attendance

• MSE wall Rep, Resident Engineer, Inspector, Wall Foreman and Crew

• Presentation by MSE wall Rep

• Detailed MSE wall construction procedures

• Compaction of backfill and installation of soil reinforcements

• Project specific details – drainage structures, obstructions, etc

• Inspection

• What to look for, what will be required

• General discussion

• Discuss what's important to: Resident, Inspector, Contractor

Best Practices for Design and Construction

of MSE Walls

MSE Wall Construction

Best Practices for Design and Construction

of MSE Walls

Duties of MSE Wall Rep

• On site for start up of wall construction – 2 to 3 Days

• Instruct on installation of MSE wall components

• Instruct on backfilling within the MSE wall volume

• Answer questions of contractor and inspector

• MSE wall rep is NOT the Inspector

• The MSE wall Rep is employed by the Contractor

Best Practices for Design and Construction

of MSE Walls

Construction Inspection

Minimum 95%

Standard Proctor

Density Required

CONSIDER:

NHI training course # 132080:

Inspection of Mechanically Stabilized

Earth Walls and Reinforced Soil Slopes

Best Practices for Design and Construction

of MSE Walls

Backfill Selection is Critical

Clay backfill =

poor friction and

drainage

Good friction

and drainage

come from

granular

backfill

Best Practices for Design and Construction

of MSE Walls

Backfill Materials

Granular Fill

Expanded Shale

Crushed Stone

LWFC Fill

Best Practices for Design and Construction

of MSE Walls

Granular Backfill for MSE Walls

• Gradation limits per AASHTO

• Some states use different gradation limits and/or reduce fines

• FHWA allowed up to 25% fines in the early 1980s

• Backfills often exceeded this limit, up to 35% fines

• Facing panel alignment was difficult to achieve

• FHWA and AASHTO returned to 15% limit on fines

U.S. Sieve Size Percent Passing

4” 100

3” 75-100

#200 0-15

Best Practices for Design and Construction

of MSE Walls

Flat Plate Tamper

within 3 ft. of Wall Face

Compaction is Important

Minimum 95%

Standard Proctor

Density Required

Large Roller Stay 3 ft. Away

Best Practices for Design and Construction

of MSE Walls

Installation of Soil Reinforcements

Best Practices for Design and Construction

of MSE Walls

Reinforcement Connections are Critical

Best Practices for Design and

Construction of MSE Walls

Accommodating Differential Settlement

Perpendicular to the Face of Wall

2" Typical for

Normal

Construction

4" to 6" if

expect large

settlement

Best Practices for Design and Construction

of MSE Walls

Critical Bottom of Wall Details

• Adequate Foundation Soils

• Embedment

• Underdrain

Best Practices for Design and Construction

of MSE Walls

Drainage Within MSE Walls

Best Practices for Design and Construction

of MSE Walls

Angles Shift Reinforcements

at Inlets and Manholes

Best Practices for Design and Construction

of MSE Walls

Pipes Behind Walls

Best Practices for Design and Construction

of MSE Walls

Precast Traffic Barrier Design

4’-6”

Important: Coping Lip Required

Best Practices for Design and Construction

of MSE Walls

Membrane

with

Traffic

Barrier

Best Practices for Design and Construction

of MSE Walls

Locate Guiderail Posts - Skew Reinforcements

Best Practices for Design and Construction

of MSE Walls

Membrane with Guiderail Posts

Best Practices for Design and Construction

of MSE Walls

Precast Coping Detail

Best Practices for Design and Construction

of MSE Walls

There was a Reason for This!

• MSE Designer

• Civil / Structural

• Geotech• Owner

Service Life Requirements

Aesthetic Requirements

Acceptable Wall Types

Global Stability

Bearing Capacity

Settlement

Acceptable Wall Types

Internal Stability

Detailed facing and

reinforcement design

Construction drawings

Site Grading

Wall Location

DRAINAGE DESIGN

Acceptable Wall Types

Loading

Best Practices for Design and Construction

of MSE Walls

Implementing Best Practices

Produces

Beautiful Long-Performing Structures

That Reason Is …

Best Practices for Design and Construction

of MSE Walls

Some of Ohio's Best

I-90 Cleveland

(2015)

In Great

Condition!

(1984 – 33 yrs)

I-75 Dayton

(Wright

Brothers)

Best Practices for Design and Construction

of MSE Walls

Thanks for Listening

Front Street

City of Berea

Seneca-Jones Road over

CSX RR, Seneca County

US 23 & US 30 Interchange

Wyandot County