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The winning solution: realization of the wall
in gabions in Colleferro
Part two: from design choice to technical success
From design to implementation
In the previous article, we analyzed the disruption that occurred in Colleferro in February 2019. and the three design hypotheses developed for securing the slope. After careful comparative evaluation of static and functional aspects, the choice fell on the third solution: a wall made entirely of metal gabions with a height of 11.50 meters.
But what were the technical reasons behind this decision? And how did the intervention that led to the realization of one of the most important consolidation works in Europe actually develop?
The reasons for the final choice
The third hypothesis, which was also the most feasible to ensure the effective safety of the slope over time, involved the construction of a wall in gabions pre-filled load-bearing metal for a height of 11.50 m, resting on a concrete base and backfill, after laying nonwoven geotextile, inert material; at the base of the wall, a drainage system was made by laying a polyethylene pipe, corrugated double-walled, with transverse cracks and covered with geotextile; in addition, the channeling of water from the grids of the footpath located upstream of the slope was made.
The operational phases of the intervention
The intervention was carried out according to the following steps:
Step 1: Foundation preparation
Construction of reinforced concrete basement with drainage and stormwater collection system;
Step 2: Gabion assembly
Assembly of the cages and pre-filling in place of the metal gabions with stone material corresponding to the characteristics provided in the project and compaction with a vibrating plate;
Step 3: Laying
Laying of full gabions by successive rows by means of crane: the first 11 rows were made using gabions with a height of 50 cm such as to ensure higher compressive strength, as highlighted during the tests carried out at the DICAM of the University of Trento., while the last 6 rows were made with the use of gabions with a height of 1 m.
Applied structural technology: the value of Ledrosteel Boxes
The Colleferro intervention stands out as une of the most significant cases of consolidation carried out in urban areas: with an overall height of 11.50 meters, the metal gabion wall today represents one of the tallest structures in Europe built with this technology.
What made the difference was the choice of the Ledrosteel Box of Metallurgica Ledrense: pre-filled structural metal gabions designed to meet the high static requirements of the intervention, while optimizing installation time and integration with drainage systems.
Thanks to this solution, it was possible to ensure high compressive strength, durability over time, and low maintenance, contributing decisively to the technical and operational success of the work.
The result is a structure that combines safety, efficiency and sustainability, and which today represents a concrete reference for engineers and designers called upon to deal with highly complex geotechnical problems.
Eng. Alessandra Spelta
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