An engineered method used to stabilize existing slopes or excavation utilizing “top down” construction sequencing. This passive reinforcement system remediates unstable natural slopes or construct new or existing over-steepened slopes using closely spaced steel inclusions. The practice involves drilling solid or hollow bars to depths specified by a geotechnical engineer. Access Limited’s innovative Nail Launcher Soil utilizes compressed air to blast up to 20-foot-long nails into the slope at speeds reaching 250-mph.
Soil nails are reinforced bars installed in soil mass. Soil nails can be installed in a variety of methods including drilled, driven, or launched nails and can be installed in a wide range of soil conditions accommodating changes in ground conditions. Soil nails perform well under seismic loading due to coupling with the ground. Each installed nail is a soil probe which can aid in design refinement during construction. Soil nails are part of a soil-structure system, consisting of the following elements: earth materials, tendons, grout, facing, connections, and drainage.
Self-drilling soil nails are uniquely suited for collapsing soil or actively moving landslides. This nail type can be used for rock or soil masses. Self-drilling nails have a high installation rate and high pullout capacity.
Open hole soil nails use the nail itself to drill the hole, using grout as the drilling fluid. The nails are hollow in the center and the grout travels down the bars and out from holes in a sacrificial drill bit. Once a nail has been drilled, it is detached from the drill and left in place. This technology combines the three-step installation of a soil nail (drilling, installing bar, and grouting) into one. Its primary advantage is not only the grout keeps the drillhole open during drilling, but the rotation from the drill bit mixes grout with the soil surrounding the drillhole, resulting in a rough, irregular effective grout column that is larger than the diameter of the drill bit.
Unlike traditional drilled and grouted soil nails, launched soil nails have a high shear capacity to axial capacity ratio. Shear capacities of up to 20% or more of axial pullout capacity have been observed. Because of this divergence, the shear component of a launched soil nail is not ignored as it would be in traditional soil nail design using grouted soil nails. The general design procedure of a launched nail wall is similar to other soil reinforced retaining structures. The design has to satisfy three types of stability requirements: internal stability(including failures due to nail shear or tensile failure, pullout, and head strength or facing failures); external stability (overturning, sliding, and bearing capacity failure); and global stability.
The installed nails are usually fully grouted and installed at a slight downward inclination, with the elements installed at regularly spaced points across the slope. Steel-reinforced rigid shotcrete or flexible wire mesh is often applied as facing to add strength and erosion control.
Soil nail components may also be used to stabilize retaining walls and levees as remedial measures. An advantage of a soil nail wall is its cost-effectiveness over other alternatives. When conventional soil nailing construction procedures are used, a soil nail wall is much more economical than concrete gravity walls and, similarly or more cost-effective than ground anchor walls.
When the requirement arises to stabilize slope erosion and slope failure so they don’t endanger personnel and infrastructure, Access Limited provides innovative technologies, fast action, and comprehensive solutions. For over twenty years, our teams have been mitigating landslides and providing residential slope stabilization, slope monitoring, slope protection, and landslide prevention services.
If you are interested in a no-obligation site visit to determine if our services fit your geohazard mitigation needs, call us at 855.905.2460 or fill out our contact form.
