Bearing plates are used with rock anchor installations to provide aerial support and load distribution to the rock surface in the vicinity of the installation. Bearing plates differ in their surface profile, material thickness and size, as well as hole diameter.
Flat bearing plates are simple plates, provided with a hole for the bolt.
The surface of the plate is pressed into a domed profile. Dome bearing plates are selected for applications where the hole and the rock surface are not at right angles, for example angled holes or uneven rock surface. Used with a spherical seat or a ball-nosed nut the bearing plate is able to articulate under the seat enabling self-alignment and ensuring flush contact with the rock surface.
The hole in the domed bearing plate is therefore necessarily of a greater diameter than the bar diameter. The domed profile also provides greater pull-through strength, enabling the steel content to be optimised.
The surface of ribbed bearing plate is pressed into four ribs, radiating from a domed central portion around the hole.
The ribbed profile provides strength and stiffness. Ribbed bearing plates are selected for applications where bolts are installed at right angles to the plane of the rock and where flat rock surfaces are experienced. The hole size provides a loose fit for the bar but does not allow excessive play.
Most bearing plates are provided with a dog ear corner equipped with a hole. This provides for the suspension of lightweight items such as trailing-cables, vent brattices, etc.