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# Launched Soil Nail

The Launched Soil Nail support type can be used to model launched soil nail slope reinforcement. Note:

• A Launched Soil Nail is generally a tube with a solid bar around it. However a solid bar can also be modeled by setting the appropriate parameters to zero.
• They are launched into the soil, and often used as a quick fix for slopes that are about to fail.

NOTE: make sure that you have read the Overview of Support Implementation topic, for important information which applies to all support models in Slide2.

## Out of Plane Spacing

The spacing between soil nails in the out-of-plane direction (i.e. along the slope).

## Force Application

See the Force Application topic for a discussion of the significance of Active and Passive support force application in Slide2.

Outer Tube

The outside and inside diameter of the outer tube and its yield stress are input here.

Inner Bar

The diameter of the outer tube and its yield stress are input here.

Resistance Type

Shear or Tensile resistance or both can be considered. These are explained below.

Tensile Resistance

Allowable nail pullout resistance per unit length is calculated as:

Shear Resistance

For more information on the procedure outlined below, please see FHWA Application Guide for Launched Soil Nails.

1 Ultimate shear resistance

Ultimate shear force is defined as:

2 Moment strength of composite nail

3 Moment at slip surface

The moment at the slip surface is defined as:

This can be rearranged as:

The equation above can be substituted into the equation from part 1:

4 Allowable shear resistance

The allowable shear resistance is divided by the factor of safety for shear:

5 Bearing capacity

In the above, we can define:

The allowable shear resistance in step 4 is the one used in the software, when the shear resistance option is selected.

## Force Orientation

The orientation of the applied support force depends on the Resistance type.

• If the Resistance Type = Shear, then the orientation of the support force will be perpendicular to the nail.
• If the Resistance Type = Tensile, then the orientation of the support force will be parallel to the nail.
• If the Resistance Type = Tensile and Shear, then the orientation of the support force will be at some intermediate angle determined by the magnitudes of the Shear and Tensile forces.