Hollow Bar Friction Anchoring Systems - Earth Shoring

Soil Nailing

Soil Nailing is a method of earth reinforcement. It is a very economical process which allows a controlled improvement of the natural stability of the soil. Soil nails provide friction, shear and tension strength in loose materials, combining all into a new monolithic structure.

Soil Nailing consists of three basic elements:

• Existing soils or weathered rock,
• Injection grouted, "self-drilling" soil nails
• Surface treatment with reinforced shotcrete, geotextile mesh or tensioned wire nets on slopes of more than 70 degrees

Soil nails guarantee the maximum shear value at the grout/ground interface. The tremi grouting through the hollow bar fills all cracks and fissures on the way to the surface, producing a grout body of approximately twice the diameter in comparison to conventionally grouted solid bar soil nails in non-cohesive soils.

The dynamic rotary drilling and injection grouting process penetrates into loose material around the annulus increasing the surface friction dramatically compared to traditionally installed nails.

Soil nails differ from grouted piles, which act independently, and ground anchors, which transfer loads via walls or whalings. Soil nails are installed, in a grid pattern, in the active zone intersecting the perceived slip plane and penetrating the passive zone. Soil nails are unstressed until ground movement takes place. When movement occurs the shear and tension values in the grouted soil nails are activated.

Soil nails can take up tension and shear forces as well as bending moments. The friction value of the soil determines the grid spacing of the soil nails. Correct design of the grid and soil nail lengths, results in a monolithic structure capable of supporting required loads.

Installing Soil Nails - Illinois Medical Center, Peoria, IL: