Support of Excavation Utilizing Helical Soil Nails with High Tensile Wire Mesh-Paper

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The paper presents helical soil nails with high-tensile wire mesh as an alternative for temporary or permanent support of excavations. Steel shafts fitted with small helices reinforce the soil, while mesh installed over geofabric retains the excavation face. Nails are typically spaced 4–6 feet apart horizontally and vertically, with lengths roughly comparable to excavation height.<br /><br />Because the system uses no grout or concrete, excavation can continue immediately after installation, avoiding curing delays, weather-related placement issues, and some quality-control challenges. It requires relatively small equipment and crews, and nails and mesh may be removed and reused. These features make the system useful in confined sites, areas with limited clearance, and projects with tight schedules.<br /><br />Limitations include difficulty installing nails through large cobbles or boulders, the need for soil to stand temporarily during staged excavation, and potentially greater wall deflection than with rigid shotcrete facing. Dense soils or taller walls may require larger, more expensive nail shafts to stay within installation torque limits. Sensitive nearby structures therefore require careful deflection assessment.<br /><br />Case histories describe applications at the Denver Broncos’ training facility, the Pulliam Community Building, Elizabeth Train Station, and an NJDOT bridge project. Excavation heights ranged from about 5 to 17 feet; designs also accommodated constraints such as nearby foundations, active rail service, and traffic surcharges.<br /><br />The authors outline preliminary hand calculations using a reinforced soil block to assess sliding and overturning, followed by final modeling with FHWA’s SNAP 2 software. Since the program is designed for grouted nails and shotcrete, equivalent input properties must be selected to represent the helical nails and mesh. Analyses address nail and facing capacity, bearing, global stability, construction stages, and seismic loading.<br /><br />Overall, the system offers a quick, reusable, and concrete-free shoring option, provided soil conditions, installation torque, and flexible-wall movement are appropriately considered.

Keywords

helical soil nails

high-tensile wire mesh

excavation support

temporary shoring

permanent support

concrete-free system

soil reinforcement

excavation stability

SNAP 2 software

case histories