Advantages and Limitations of Soil NailingArticles > Advantages and Limitations of Soil Nailing
Advantages associated with soil nailing fall into three main categories: Construction, Performance, and Cost.
- Soil nail walls require smaller ROWs than most other competing systems. This is also true for ground anchors as soil nails are typically shorter.
- Soil nail walls are less disruptive to traffic and cause less environmental impact compared to other construction techniques such as drilled shafts or soldier pile walls, which require relatively large equipment.
- Soil nailing causes less congestion in the excavation when compared to braced excavations.
- The installation of soil nail walls is relatively fast.
- Easy adjustments to nail inclination and location can be made when obstructions are encountered, such as boulders, piles or underground utilities. As a comparison, adjustments in the horizontal position and orientation of ground anchors often require changes to the soldier pile layout or the addition of waler beams, making adjustments in the field costly.
- Soil nail wall installation is not as restricted by overhead limitation as in the case of soldier pile installation. This advantage is particularly important when construction occurs under a bridge.
- Soil nailing may be more cost-effective at sites with remote access because the smaller equipment is more readily mobilized.
- Soil nails are installed using equipment that is multipurpose and can be used for other substructure elements such as underpinning or protection of adjacent, movement-sensitive structures.
- A relatively large number of qualified soil nail contractors exists.
- A widespread knowledge about soil nailing exists among engineers.
- Soil nail walls can accommodate curves and “bends” more easily than other top-down construction wall systems, which would otherwise require straight wall segments.
- Soil nail walls are relatively flexible and can accommodate comparatively large total and differential movements.
- The measured deflections of soil nail walls are usually within tolerable limits in roadway projects when the construction is properly controlled.
- Soil nail walls have performed well during seismic events.
- Soil nail walls have more redundancy than anchored walls because the number of reinforcing elements per unit area of wall is larger than for anchored walls.
- Sculpted facings, which can be applied to soil nail walls, give a more natural appearance than other finishes, to fit in with the surrounding environment.
- Conventional soil nail walls tend to be more economical than conventional concrete gravity walls taller than approximately 12 to 15 ft.
- Soil nail walls are typically equivalent in cost or more cost-effective than ground anchor walls when conventional soil nailing construction procedures are used.
The main limitations associated with soil nailing are:
- In projects where strict wall movement criteria exist, additional measures to limit deflections may be required. These requirements would add cost. If very strict movement criteria exist, soil nails may not be a feasible option for the project.
- The existence of utilities behind the wall will likely create restrictions to the location, inclination, and length of soil nails, particularly in the upper rows.
- Soil nail walls are not well-suited where large amounts of groundwater seep into the excavation. Soil nail walls require maintaining a temporary unsupported excavation face during construction.
- Permanent soil nail walls require permanent underground easements.
- Soil nail tendons may interfere with certain types of communication lines (e.g., optic fiber) running immediately adjacent to soil nail walls.
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