Jet grouting for ground improvement in an urban setting

Works completed:

• 3,500 m³ jet grouting bottom plug
• 2,200 m of jet grouting columns

Project overview

In the municipality of Sestri Levante, Cos.Idra carried out ground improvement works in an urban setting characterised by limited working space and the presence of existing utilities. The project was aimed at improving the geotechnical properties of the ground and stabilising the affected areas.

Scope of works

The works included Ø600 mm jet grouting columns for shallow ground improvement and Ø800–1000 mm columns for deep ground treatment. The project was complemented by preliminary drilling, installation of steel reinforcement, anchors and soil nails using self-drilling bars, and sprayed concrete lining to protect the exposed surfaces.

Operational challenges

The works were carried out in a constrained urban environment, requiring careful management of interferences with existing infrastructure and continuity of operations in restricted spaces. Particular attention was paid to injection parameter control, correct column overlap and the management of works in heterogeneous soils.

Results

The project improved the mechanical properties of the ground and provided the stability required for the planned works. Coordinated use of different ground improvement technologies allowed the site to operate effectively despite urban constraints and service interference, while maintaining continuity and control throughout construction.