Open pit protection – Tobacco Factory Rovinj
In the central part of Istria, Kanfanar Municipality, there is a Tobacco factory Rovinj on a total area of 45,000 square meters. For the reconstruction and extension of the hall, the geotechnical exploration and investigation works were executed. For the purpose of the open pit protection, we made the main and detailed design.
Based on the proximity of the extension, it was necessary to foresee a vertical excavation of the construction pit next to the existing hall. It was determined that the foundations were built within the made ground which conditioned open protection to prevent underpinning in the excavation phase and the potential damage and costly remediation of the foundations.
The open pit protection consists of reinforced concrete drilled piles with a diameter of D = 310 mm. The distance between piles is 80.0 cm to 100.0 cm. The piles are executed through the made ground and the bedrock with impact rotary drilling technology. After drilling, steel profiles IPE 160 of steel S235 and concrete with a compression strength class C 30/37 were installed in the borehole.
The piles are executed from the bottom of the existing foundation to a depth of 1.75 m below the open pit bottom. The total length of reinforced concrete piles is L = 4.60 m and 4.75 m with a length of steel profiles L = 5.0 m. For the purpose of connecting the piles, a reinforced concrete beam (dimension 35×50 cm) was executed.
On the front face of the pile wall, a layer of shotcrete with a compression grade C24 / 30 thickness of 2.0 to 5.0 was applied. A layer of reinforcement mesh Q-283 was executed on the pile wall within the made ground and up to 30.0 cm below the rock mass level.