Foundation soil consolidation of an artifact at a railway building

THE PROBLEM

Preventive consolidation of the foundation soil by improving its mechanical and hydraulic characteristics through the injection of expanding resins and Uretek Deep Injections technology.

Customer needs

It was necessary to intervene quickly to make the railway safe, but impacting as little as possible on railway traffic.

Why the Uretek solution was chosen:

Speed
Careful planning and programming of the times allowed the work to be completed in just a few days;
Non-invasive
The intervention proposed by Uretek did not require excavations or masonry work, and it did not dirty the area or produce waste;
Localized work
The Uretek team delimited the work area, allowing regular work activities to continue;
Continuous monitoring of the work
Both during and after the intervention, the activities were subject to control by highly qualified personnel using advanced laser technology;
Application of the exclusive Uretek Deep Injections® technology
which, thanks to the special expanding resin Uretek Geoplus®, compacts the ground and stabilizes the structures at a high swelling pressure;
Respect for the environment
the above-ground mixing of Uretek® resins generates an inert final product, which does not release eluates into the ground and any aquifers present.
Uretek is qualified by SNCF WHO RECOGNIZES ITS KNOW-HOW IN THE RAILWAY SECTOR VALID UNTIL JANUARY 2025.
Uretek is associated CIFI, ITALIAN RAILWAY ENGINEERING COLLEGE; MAFEX, SPANISH RAILWAY ASSOCIATION and AETOS, SPANISH ASSOCIATION OF TUNNELS AND METROPOLITAN WORKS.

THE SOLUTION

The consolidation intervention concerned the ground below the foundation of an artifact in Venice and was carried out using the Multipoint injection system and Uretek Deep Injections technology, involving the sediment of the foundations of a total surface area of 22.4 m2 with the aim of obtaining an improvement in the mechanical and hydraulic characteristics of the foundation soil.

consolidamento-terreno-fondazione-fabbricato

INTERVENTION IN DETAIL

Applyed technology
The intervention involved the use of the Uretek Multipoint injection system. The main features of the system are the following:

- The consolidation work involved the sediment of the foundations with a total surface area of 22.4 m2;
- The injections were carried out with the Multipoint injection system, involving the volume of soil from 0.00 to - 4.30 m above soil;
- For each injection, the lifting of the structure was recorded, confirming the consolidation of the ground;
- The comparative penetration tests carried out before and after the works recorded an important increase in the soil resistance parameters;
- The soil bearing capacity values, calculated at ULS in post-construction conditions, are equal to 856 kPa and therefore compatible with the expected loads;
- The subsidence of the foundation, estimated considering the load of 27.50 kPa uniformly distributed on the surface, the rigid foundation and the ground with perfectly elastic behavior, are of the order of a couple of millimeters.

INTERVENTION PLANIMETRY

Estimate of breakdowns
The estimate of the total settlements that may develop over time following the application of the overall load was conducted considering the infinitely rigid foundation, the load evenly distributed on the support surface and the soil with elastic behavior.

Laser monitoring
During the resin injection operations, in order to check the behavior of the structure with regard to vertical displacements, a laser instrumentation with a precision of ± 0.5 mm was used.
The receivers, positioned on the foundation structures, detected a maximum lifting of the concrete base of 1.0 -1.5 mm, confirming the consolidation of the base soil.

Penetrometric tests
The positive outcome of the intervention was checked with comparative dynamic penetrometric tests that made it possible to appreciate the increase in the mechanical parameters of the injected soil volumes.