Open pit protection and foundation design for the residential and commercial building in Pula
In the central part of the city of Pula, within a residential block, the construction of a residential and commercial building is planned. The future building will be terraced, with 5 floors.
Engineering and geological as well as geotechnical investigation and testing was carried out for the purpose of an open pit protection and foundation design. The works consisted of engineering and geological prospecting of the terrain, exploratory drilling with coring, core determination, the laboratory testing of samples and processing of data from earlier investigations. For the construction of the future building, it is necessary to cut into the existing terrain down to approx. 4.50 m and secure a temporary open pit.
Within Zone 1 of the open pit protection, securing a vertical excavation protection measuring 3.20 m in height is planned, via the construction of a cantilever pile wall made of reinforced concrete drilled piles. Within Zones 3, 4 and 5 of the open pit protection, securing a vertical excavation protection measuring up to 2.90 m in height is planned, via installing self-drilling anchors and shotcrete as well as a reinforcing Q-188 mesh (nailed soil system). Shorter self-drilling anchors were chosen for one part of the project because of the fact that there is a basement floor of the neighboring building at a distance of about 1.70 m behind the face of the open pit. In one part of the open pit (Zones 2, 6, 7 and 8), securing the walls and staircases of the existing neighboring buildings is planned. It is in order to perform a vertical excavation measuring up to approx. 4.50 m in height directly next to the foundations and staircases of the existing buildings by underpinning the existing buildings in horizontal and vertical sections. The construction of an underpinned wall of the open pit through which self-drilling anchors are to be installed is planned. For the purpose of an additional connection of the sections of the underpinned wall to each other, as well as to the lower parts of the existing buildings, it is planned to install shotcrete in two layers measuring 5.0 cm in thickness on the face of the wall, the staircase and the lower parts of the existing buildings, between which a reinforcing Q-188 mesh is to be placed in a single layer. It is planned for the foundation of the northern extension of the building to be built on a base plate measuring 60.0 cm in thickness. In order to eliminate excessive differential settlement, it is planned to replace the material under the entire surface of the base plate.
