These techniques are generally used to stabilize stony slopes, subject to  falling or collapsing, or they can be also combined with the building of walls and bulkheads.
Tie-rods are elements of  the frameworks operating  in traction and able to empower the material.
A tie-rod is made by a head and a foundation. The head has a share out platform and a blocking device, connected to a free part including the strained portion, and the covering sheath. The foundation is essentially a frame (built with bars, threads, or thread-ply shaped) covered by a corrugated sheath, if necessary.
Initially,  the traction force of the tie-rod is transmitted from the head to the blocked frame or the heap of rocks. Then, the free part transmits the traction force from the head to the foundation. Finally, the traction forces of the tie-rods is transferred from the foundation to the stony heap.
Foundations can be blocked mechanically or by a concrete built-in blocking device and they are carried out within the stable soil portion or rocky areas, far from the directly areas of interventions now moved.

Blocking heads  are usually cemented to a supporting frame (walls, bulkhead, piles) while blocking tie-rods can be:

-    active or pre-strained ties if the tension generated during installation is the same as the work tension.
-    partial pre-strained ties if the tension generated is lower than the work tension.
-    passive or non pre-strained ties  if tension progressively increases as much as deformities.