Earth retaining structures are engineered to retain a soil and/or rock mass adjacent to an area, building or structure, and are commonly used to accommodate changes in grade and provide a right-of-way. There are several types of retaining structures ranging from gravity retaining walls that rely on their weight to resist lateral pressures to anchored/tieback walls that rely on ground anchors for stability. Mechanically stabilized earth (MSE) walls have gained wide acceptance in highway, commercial and residential construction because of their relatively low cost, efficiency in construction, flexibility in civil design, and aesthetic appeal. These walls are gravity-type retaining walls that rely on a metal- or geosynthetic-reinforced earth mass for stability. The Federal Highway Administration estimates that more than half of all retaining walls constructed every year for transportation applications in the United States are MSE walls with precast facing, and designers of MSE walls continue to push the design envelope in terms of wall height, length of the reinforced zone, and quality of backfill soils. The popularity of this wall system has generated several management and review challenges for owners and approving agencies, as an increasing number of MSE wall systems are being marketed by specialized consultants and/or contractors instead of being designed by a project designer/structural engineer as is typically the case.

Learning Objectives:

• You will be able to review planning aspects related to the selection of earth-retaining structure types.
• You will be able to discuss design and construction considerations related to loads acting on earth-retaining structures, including water and seismic loads, and generally accepted good construction practices.
• You will be able to review performance assessment and failures of earth retaining structures, including their performance during earthquakes.
• You will be able to discuss MSE walls.