<p><p><figure id='attachment_2630' style='max-width:658px' class='caption aligncenter'><img class="wp-image-2630 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Schematic diagram showing a shored mechanically stabilized earth wall system. The shored portion of the wall is on the left and the mechanically stabilized earth wall is on the right." width="658" height="413" /><figcaption class='caption-text'> Generic Cross Section of an SMSE Wall System (Figure from Morrison et al. (2006))</figcaption></figure><h2>Basic Function</h2>Shored Mechanically Stabilized Earth Wall Systems (SMSE) creates a composite retaining wall system which can be used for widening of existing roads.<br><h2>Advantages:</h2><ul> <li>Suitable where limited space is available</li> <li>Shorter reinforcement is needed</li> <li>Shoring minimizes the disturbances behind the MSE wall</li> <li>Shoring reduces the lateral load on the MSE wall</li></ul><h2>General Description:</h2>SMSE walls combine soil nailing with Mechanically Stabilized Earth walls to create a composite wall system which can be used in mountainous terrain.<br><h2>Geologic Applicability:</h2><ul> <li>May not be suitable when soil is particularly weak or highly plastic, soft, and/or organic</li> <li>Dewatering may be necessary if the groundwater table is high</li> <li>Boulder, cemented layers, or other similar geology may limit shoring type</li> <li>Shoring type will also be affected by the cohesion and stand up time of the soil</li></ul><h2>Construction Methods:</h2>It is recommended that the shoring design follows the guidelines described in Lazarte et al. (2003) for conventional soil nails and Sabatini et al. (1999) for ground anchors. Using soil nailing combined with MSE walls in SMSE walls reduces the minimum length of the reinforcement for the MSE portion of the wall from 0.7 times the height to 0.3 times the height. Excavation to create a flat surface to construct the wall on is needed in steep terrain. Public-sector methodologies provide minimum bench width for MSE walls and reinforcement length equivalent to seventy percent of the design height of the MSE wall. For taller walls the excavation can be large. Soil nails are used to stabilize the excavation with the MSE wall being constructed in front of it. A drainage system is needed for the shoring and MSE walls to reduce lateral hydrostatic pressure.<br><h2>Additional Information:</h2>SMSE walls require shorter reinforcement which will minimize excavation and reduces the disturbance on the environment compared to MSE walls. The SMSE wall system was developed for low volume roads in mountainous terrain. This technology has not been fully developed and is therefore not recommended for urban areas. Areas of the design that should be evaluated further for urban areas include potential for development of tension cracks under dynamic effects of traffic loading, seismic events, and the performance of traffic barriers. To provide QA/QC, a monitoring program should be used for each SMSE wall constructed until adequate performance is proven. SMSE wall systems should be evaluated for cost effectiveness compared to other technologies that may be more economical depending on the site.<br><h2>SHRP2 Applications:</h2><ul> <li>Roadway and embankment widening</li></ul><h2>Example Successful Applications:</h2><ul> <li>El Portal Road – Yosemite National Park, CA</li> <li>Ice House Road – Eldorado National Forest, CA</li> <li>Landslide Stabilization, US Highway 26-89 MP 131.8 –Wyoming</li></ul><h2>Complementary Technologies:</h2>Light weight fill can be used in the reinforced zone. Not typically used in conjunction with other technologies. Alternate Technologies: MSE walls, modular block/geosynthetic walls, reinforced soil slopes, and other earth retaining structures.<br><h2>Potential Disadvantages:</h2><ul> <li>Relatively new system.</li> <li>Limited case histories documenting successful applications.</li> <li>Application is currently restricted to low volume roads in mountainous terrain by FHWA.</li> <li>General contractors, specialty contractors, and consultants will have limited or no experience with SMSE wall systems.</li></ul><h2>Key References for this Fact Sheet:</h2>Lazarte, C.A., Elias, V., Espinoza, R.D., and Sabatini, P.J., (2003) Geotechnical Engineering Circular No. 7 Soil Nail Walls, FHWAA0-IF-03-017.</p><p>Morrison, K.F., Harrison, F.E., Collin, J.G., Dodds, A., and Arndt, B. (2006), Shored Mechanically Stabilized Earth (SMSE) Wall Systems Design Guidelines. Report No. FHWA-CFL/TD-06-001. FHWA.</p><p>Sabatini, P.J., Pass, D.G., and Bachus, R.C. (1999) “GEC No. 4: Ground Anchors and Anchored Systems.” Report No. FHWA-IF-99-015, FHWA.</p></p>