Introduction

Mechanically stabilized earth (MSE) walls, also called reinforced soil walls, are commonly used structures for retaining the earth under bridges, highways, railroads, water front ports, and various other types of infrastructure. These walls are constructed from the bottom up by placing alternating layers of soil and reinforcement. The reinforcement could be a relatively extensible product such as a geogrid or geotextile or a more rigid product such as steel ribbed strips. The reinforced soil is usually engineered granular material and the facing of these walls is typically inclined at greater than 70 degrees.

Designing an MSE wall requires consideration of the geometric configuration and reinforcement requirement to ensure external and internal stability. External stability is concerned with the global stability of sliding masses defined by slip surfaces that pass outside the reinforced soil zone. Internal stability is concerned with rupture and pullout of the reinforcement. Both modes of internal stability are assessed using empirically derived relationships that estimate stress states within the ground and reinforcement. SLOPE/W can only be used to analyze the stability of sliding masses. Slip surfaces can pass outside or through the reinforced zone. Slip surfaces that pass through the reinforced zone benefit from the reinforcement behind the slip surface; however, the results of the analyses cannot be used to assess rupture and pullout.

The objective of this example is to demonstrate how SLOPE/W can be used to analyze external stability and compound failures; that is, slip surfaces that pass through the reinforced zone behind the MSE wall. A commentary on internal stability is also provided to highlight the distinction between it and compound failures.