Project: Residential multi-storey building
Location: Italy
Year: 2007
Duration: 31 days
Technology: DEEP INJECTION & SLAB LIFTING
Strengthening the foundation of a multi-storey residential building
Problem
Cracks in the building abutment area
Solution
Reinforcement of the foundation soil and elimination of subsidence
Consisting of two buildings (B1 and B2) separated by a structural joint, the residential complex was built between 1992 and 1994 and comprises six above‑ground floors and two floors intended for basements and garages. The foundation consists of a perimeter curb and reinforced concrete footings.
Problem
Shortly after construction, cracks began to appear in one of the two buildings (B1), which gradually widened over time, particularly in the upper part of the connection zone between the two buildings, with a maximum gap of approximately 5 cm. After a geological survey of the site was carried out, loose and silty plastic clays and dense plastic clays were found. Initially, mixed‑type foundations on a slab base were designed. Since the geological surveys revealed the presence of plastic clays, the damage to building B1 could be attributed to several main factors: the presence of predominantly clayey soils of the plastic category with high compression/expansion potential due to changes in water content, which led to a change in the volume occupied. In addition, poor waterproofing and paving of the areas adjacent to the building may have contributed to these causes.
Objectives:
The solution implemented by Uretek, aimed at strengthening the foundation, was directed at filling voids in the foundation soil, while increasing its bearing capacity and displacing water from the pores.
Objectives:
The solution implemented by Uretek, aimed at strengthening the foundation, was directed at filling voids in the foundation soil, while increasing its bearing capacity and displacing water from the pores.
The project in detail
Technology applied:
Uretek Deep Injection technology was used with special Uretek geopolymers, applied in two stages:
STAGE 1 – Surface compaction of soils: injection is carried out into the concave surfaces of the foundation arch to improve the geomechanical characteristics of the soils and fill macroscopic voids in the soil foundation surface.
STAGE 2 – Deep strengthening: injections were carried out at deeper levels, within the volume of soils subject to the loads transmitted by the building.
Uretek Deep Injection technology was used with special Uretek geopolymers, applied in two stages:
STAGE 1 – Surface compaction of soils: injection is carried out into the concave surfaces of the foundation arch to improve the geomechanical characteristics of the soils and fill macroscopic voids in the soil foundation surface.
STAGE 2 – Deep strengthening: injections were carried out at deeper levels, within the volume of soils subject to the loads transmitted by the building.
Solution
The success of this solution was confirmed by laser monitoring during injection and by tests carried out after the work, which made it possible to assess the increase in the mechanical parameters of the foundation soils. The effectiveness of this procedure was demonstrated by the vertical lifting of the building by an average of 2 mm. In total, 176 linear metres of strip foundation and 4 slab foundations were strengthened. The work lasted 31 calendar days.
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