<p><p><figure id='attachment_1518' style='max-width:1024px' class='caption alignnone'><img class="wp-image-1518 size-large" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Schematic diagram showing the principal elements of a mechanically stabilized earth wall." width="1024" height="509" /><figcaption class='caption-text'> Mechanically Stabilized Earth Wall System. Berg, R.R., Christopher, B.R. and Samtani, N.C. (2009). Design and Construction of Mechanically Stabilized Earth Walls and Reinforced Soil Slopes, FHWA NHI-10-024 Vol I and NHI-10-025 Vol I</figcaption></figure><h2>Basic Function</h2>Mechanically Stabilized Earth Wall Systems (MSE walls) use reinforced soil to create a composite retaining wall system which can be used where change in grade is necessary.<br><h2>Advantages:</h2><ul> <li>Simple and rapid construction procedures</li> <li>Reduced right of way</li> <li>Cost effective compared to traditional walls</li> <li>Aesthetically pleasing appearance</li></ul><h2>General Description:</h2>Reinforced soil consists of tensile reinforcements added to soil to form a stronger composite material mass. The general acceptance, expiration of patents, and widespread use of this type of construction has led to generically naming retaining wall construction as Mechanically Stabilized Earth Walls (MSEW). Reinforced soil structures are generally classified as a wall when the face batter is equal to or greater than 70 degrees from horizontal, and are classified as Reinforced Soil Slopes (RSS) when the face batter is shallower. MSE walls are cost effective compared to conventional concrete cantilever retaining wall systems, especially for walls in fill embankment cross sections, and should be considered when selecting a retaining wall type. Furthermore, MSE walls are more flexible than conventional retaining walls and, therefore, are suitable for sites with poor foundations and seismically active areas. Recent related developments in reinforced soil applications such as modular block/geosynthetics walls and Tecco mesh/ shotcrete facing systems are included with the MSEW technology.<br><h2>Geologic Applicability:</h2><ul> <li>Particularly suited to economical construction in fill embankments, steep-sided terrain, in ground subject to slope instability or in areas where foundation soils are poor.</li> <li>Cost-effective alternatives for most applications where reinforced concrete or gravity type walls have traditionally been used to retain soil.</li> <li>Bridges may be supported directly on top of the MSEW(via a spread footing) or on deep foundation elements that pass through the reinforced soil mass.</li> <li>Also used for temporary structures, which is especially cost-effective and time-efficient for temporary detours necessary for highway reconstruction projects.</li></ul><h2>Construction Methods:</h2>Construction is well established, using placement of reinforcement followed with compaction of the fill over the reinforcement..<br><h2>Additional Information:</h2>A variety of facings for MSE walls are currently available and in use. Common facings include: precast concrete panels, dry cast modular blocks, gabions, L-shaped welded wire mesh, shotcrete, wood lagging and panels and wrapped sheets of geosynthetics. Currently, most process patents covering soil-reinforced system construction or components have expired, leading to a proliferation of available systems.<br><h2>SHRP2 Applications:</h2><ul> <li>Roadway and embankment widening</li> <li>Stabilization of pavement working platforms</li></ul><h2>Example Successful Applications:</h2><ul> <li>12.6 m High Geotextile-reinforced Wall, Seattle, WA</li> <li>Crosstown Project, Minneapolis, MN</li> <li>Veterans Memorial Overpass, Tucson, AZ</li></ul><h2>Complementary Technologies:</h2>Reinforced soil slopes, Shored MSE wall systems, lightweight fills, column supported embankments.<br><h2>Alternate Technologies:</h2>Traditional concrete cantilever retaining wall structures and reinforced soil slopes.<br><h2>Potential Disadvantages:</h2><ul> <li>Corrosive nature of fill material on reinforcements</li> <li>May require large space behind wall to obtain sufficient internal and external stability</li> <li>Wide variety of facings available and selection of appropriate facing not well defined</li> <li>Clay and silt soils have poor drainage and are poor fill materials.</li> <li>Durability of some reinforcements may reduce service life</li></ul><h2>Key References for this Fact Sheet:</h2>AASHTO (2010). LRFD Bridge Design Specifications. 5th Edition, American Association of State Highway and Transportation Officials, Washington, D.C.</p><p>Berg, R.R., Christopher, B.R. and Samtani, N.C. (2009). Design and Construction of Mechanically Stabilized Earth Walls and Reinforced Soil Slopes, FHWA NHI-10-024 Vol I and NHI-10-025 Vol II.</p><p>Tanyu, B.F, Sabatini, P.J and Berg, R.R (2008). Earth Retaining Structures Reference Manual. U.S. Department of Transportation, Federal Highway Administration, Washington, D.C., FHWA NHI-07-071, 654 p.</p><p>Sullivan, J. (1996). Pavement Recycling, Executive Summary and Report. FHWA-SA- 95-060.</p></p>