Hydro Buildings Consolidation s.r.l.
Via Alessandro Tiarini, 27/A - 40129 - Bologna - Italia
C.F. / P.Iva: 02836401204
Tel: 342 832 8237 - 051/6350845 - Fax: 051/6354238
Relief of the structure and historical vicissitudes
The supporting structure is in brick masonry and consists of longitudinal external walls of two heads and a spine wall, two heads in the basement and a head on the upper floors, while the floors are in varese beams and large blocks. The foundations, built from scratch in 2001, are of the strip type and consist of reinforced concrete beams with a width of 50 ÷ 80 cm and a height of 40 ÷ 50 cm.
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Sections of foundation beams
performed in 2001
Cracking state survey
The crack pattern detected indicates the existence of a generalized phenomenon that affects the entire building; it is not a local mechanism linked to any particular factor. The movements affect both the external walls and the spine wall and are reflected on the floors which, having no reinforced slab, since this was not done at the time, are unable to oppose transverse tractions and are damaged in the direction of the warp.
Geological and geotechnical framework
The subsoil is made up of materials that show strong variations in volume as their water content varies. By examining the graphs relating to natural humidity, it is clear that the foundation soil has undergone shrinkage and swelling processes. In particular, the thicknesses affected by these phenomena are at least three meters in correspondence with test n. 1 (left rear corner of the building) and at least four meters in correspondence of the essay n. 2. (right front corner). To better understand the situation, refer to the attachment "Humidity trend in relation to the foundations" where the graphs relating to humidity and a section of the building, including foundations, have been superimposed, referring to the actual height of the upstream and Valley. It is noted that the humidity value in the two to three meters below the foundations is significantly different between upstream and downstream. Furthermore, it is clear that drying is much greater downstream where the thickness of the soil protecting the foundations is lower. It should also be borne in mind that the building's sediment area, unlike the courtyard, does not undergo direct water contributions and therefore is substantially subject to progressive drying with consequent shrinkage. It is therefore evident that the foundations of the building insist on layers of soil subject to shrinkage and swelling as a function of natural variations in humidity and that these phenomena, being necessarily inhomogeneous, cause stresses that the structure of the building is not able to absorb without being damaged. . As further proof of what has been said, it is important to point out that in early May 2009, during the preparatory inspection of the geotechnical investigations, we were able to detect a significant reduction in the opening of the lesions on the rear external wall compared to December 2008, an unequivocal sign of the swelling. of the land. In conclusion, given the crack pattern, given the characteristics of the ground, given the distribution of moisture in depth and having verified the conspicuous closure of the cracks in the winter and spring period, I believe that the crack pattern of the building is essentially due to the movements induced by the shrinkage and by the swelling of the foundation soils in relation to their water content.
Stratigraphy of the site under examination
Boundary conditions and probes positioning
Physical and granulometric characteristics
Variation of water content with depth
Project of the intervention
The consolidation project involves the installation of an HBC system consisting of a series of vertical diffusers, suitably made and spaced, connected to control and management devices that allow to supply water to the ground if, when and where it is needed regardless of the causes. which generate variations in humidity.