Fully Bonded Bolts

The Fully Bonded bolt model in RS3 works as follows:

• Fully Bonded bolts are divided into bolt elements according to where the bolts cross the finite elements. These bolt elements act independently of each other – neighbouring Fully Bonded bolt elements do not influence each other directly, but only indirectly through their effect on the rock mass.
• The strength and stiffness of the rock/grout and bolt/grout interfaces are NOT accounted for – the bolt is assumed to remain fully bonded to the rock, and no interface effects are considered.

Failure Mechanism

• Failure of a Fully Bonded bolt element occurs in tension, when the axial force on the bolt element exceeds the axial capacity. Failure of an element of a Fully Bonded bolt does not necessarily imply failure of adjacent elements on the same bolt. If you view yielded bolt elements after the analysis you will see that Fully Bonded bolts can show yielding in some elements and not in others.
• A Fully Bonded bolt element can still have a residual capacity (i.e. it can still carry load) after the peak capacity is exceeded.

For more information regarding the bolt models and their numerical implementation in RS3 see the Bolt Formulation document in the Theory section.

The following properties define a Fully Bonded bolt in RS3.

Bolt Diameter

The diameter of the bolt.

Bolt Modulus

The Young’s Modulus of the bolt steel.

Tensile Capacity

The peak tensile capacity of the bolt.

Residual Tensile Capacity

The residual tensile capacity of the bolt (i.e. the tensile capacity of the bolt after the peak tensile capacity has been reached).

Pre-Tensioning Force

See the Pre-Tensioning topic for information.

Joint Shear

See the Joint Shear topic for information.