Open pit protection and foundation design – UPOV Požega
In the eastern part of the city of Požega, the reconstruction and extension of the Požega agglomeration wastewater treatment plant (UPOV Požega) is planned. For the construction project, we made the main and detailed temporary open pit protection and foundation design for the following facilities:
– facilities of the biological block (floor plan dimensions approx. 100.0 x 50.0 m);
– septic reception facility (floor plan dimensions approx. 10.0 x 6.0 m); and
– the added part of the building next to the administrative building (floor plan dimensions approx. 10.0 x 5.0 m).
Prior to the creation of the main and detailed designs, the following geotechnical investigations and testing were carried out: exploration drilling, dynamic tests, geophysical tests, engineering geological mapping of terrain and determination of drill cores and laboratory sample testing.
The temporary open pits for the biological block facilities and the septic tank reception facility are planned through a combination of a wide excavation at a slope of 1V:1.50H and a vertical excavation with additional protection. The expected cutting depth for both pits is up to 6.0 m in relation to the level of the existing terrain. The vertical excavation with additional protection is planned because of the immediate proximity of the sewage pipes, which must remain functioning, and in relation to the face of the open pits.
The foundation of the future biological block facilities and the septic reception system is carried out on foundation slabs. In order to unify the conditions of the foundation soil with regard to the variable directions of layers of different deformability along the project, soil arrangement under the foundation slabs is carried out by replacing the material. For the replacement, stone material with a thickness of 50.0 cm was installed. In order to separate the soil layers with significantly different characteristics, geotextiles were installed on the bottom of the open pit excavation, before replacing the material.
