Soil Nails - Bearing Plates and Facings

Soil nail facings are split into three categories:

• Soft – Erosion Control Matting
• Flexible – Hi Tensile Steel Meshes
• Rigid – Shotcrete

Facing systems provide a combination of structural facing and erosion control. The factors considered when determining the type of facing are slope geometry, geotechnical characteristics and environmental effects such as surcharge at crest and desired design life.

The use of different facings can have a significant effect on the soil nail design influencing spacing & shape of the nail pattern as well as the strength and size of the bar selected.

Bearing plates are used primarily to secure facings. Plates also provide an element of confinement, in conjunction with the retention effect of the fully bonded nail in the wedge zone. Centres for and lengths of soil nails should be defined by assessing the global stability of the slope first and then the internal checks including the superficial failures on the slope surface can be considered.

Angle compensation between the bearing plate and the soil nail must be addressed to ensure full seating of the plate against the face. For flatter slopes (25° to 30°), the amount of angle compensation is significant and can be up to 50°. See below for angle compensation options.

Erosion control matting offers a practical solution for most slopes up to 45°; above this angle facings with structural stiffness to resist bulging are required such as High Tensile Steel Mesh systems or for some vertical faces sprayed concrete may be required.