A prestressed grouted ground anchor is a structural element installed in soil or rock that is used
to transmit an applied tensile load into the ground. Ground anchors, are installed and then the
drill holes are filled with grout. The basic components of a grouted ground anchor include the:
(1) anchorage; (2) free stressing (unbounded) length; and (3) bond length. These and other
components of a ground anchor are shown schematically in figure 3.1.
6
The anchorage is the combined system of anchor head, bearing plate, and trumpet that is
capable of transmitting the prestressing force from the prestressing steel (bar or strand) to the
ground surface or the supported structure. The unbounded length is that portion of the
prestressing steel that is free to elongate elastically and transfer the resisting force from the
bond length to the structure. The tendon bond length is that length of the prestressing steel that
is bonded to the grout and is capable of transmitting the applied tensile load into the ground.
The anchor bond length should be located behind the critical failure surface.
Figure 3 – Components of a ground anchor.
In terms of design life, there are two types of ground anchors:
 temporary ground anchors are defined as those which are required to be in service no
longer than two years;
 permanent ground anchors are defined as those which are required to have a design
life of more than two years.