Tieback & Compound

Besides sliding and pullout internal verification it is possible to carry out the verification of the containment works in regard to potential failure surfaces.

The verifications are: Tieback & Compound

Tieback analysis (internal stability analysis)

This kind of verification is useful to determine if the tensile strength of each reinforcement is sufficient to ensure the reinforced earth from possible internal collapses due to its own weight and to overloads. It therefore ensures against any sliding along surfaces that emerge on the face of reinforced earth. The ability of tensile strength of the reinforcement is calculated in order to determine whether the anchorage of the reinforcement in the ground is such as to avoid the collapse for sliding along the potential failure surface. Tieback analysis is performed with the classical methods of slope stability like bound computation by one point point corresponding to the position of each reinforcement on the face of the work. This analysis allows to obtain an even distribution of the stresses in the reinforcements.

Compound analysis (composed stability analysis)

The use of Tieback analysis ensures against any internal damages; on the other hand the capacity of the reinforcements to develop their own resistance depends on their pull-out resistance and, therefore, on their anchoring in a stable zone. However for deeper sliding surfaces and/or sliding surfaces passing through the foot of the slope, these resistances can be reduced and therefore cause instability. Therefore it becomes necessary a stability analysis that allows to determine whether the length of the first k reinforcements is such as not to cause sliding along the sliding surfaces above. This is definitely a conservative verification but it ensures the translational and rotational stability of the whole complex.

The analysis is carried out with the limit equilibrium methods, for both circular and free form surfaces.