The instability of slope (Cut 2), displacement of supporting structure (Cut 5) and breakage and sliding of material appeared on the motorway section from Grdelica to Predejane (LOT 1, the Main Contractor was the Spanish company Azvi) during 2018.
Koridori Srbije d.o.o. (LLC) engaged the company “Integral Inženjering“ to execute works on slope protection. By the end of works on Cut 2, the 26 kilometres long section of the motorway through Grdelička klisura will be opened for traffic. Execution of the remaining works on the rehabilitation of Cut 5 will be continued in upcoming period. These works will not disturb the traffic flow and will not have a negative impact on the safety of passengers.
The rehabilitation of Cut 2 – the works are in the final phase.
The emergency works were executed in the intitial period. The removal of hill and material was performed during the day, and the drilling of piles was perfomed at night.
The construction of protective structure (gallery on piles), as a permanent solution, was started after the necessary conditions were created. The total length of protective gallery is l=150 m.
The protective gallery is founded on bored piles of diameter of Ø=1.500 mm, length between l=15 and 21 m on distance s=3 m. The piles are connected with head beam of length of l=151.80 m. The reinforced concrete piles of diameter of d=1.20 on distance s=3 m which are connected that sleepers are constructed above piles from the left side and in the middle of two carriageway profiles. The piles on the right side are connected with head beam and reinforced concrete walls are constructed between piles.
The roof structrue is consicted of prestressed prefabricated T-shaped girders. The conncetion of girders with roof structure is achieved with the monolithic roof plate of thickness of d=25 cm with waterproofing above and protective layer of lean concrete.
Along with the construction of the protective gallery, the slope was released.
The rehabilitation of Cut 5 – it is performed by construction of 3 structures in two phases.
The construction of supporting structure K1 (l=411 m) was finished on October 2018 (the first phase of works). It is constructed on piles in combination with geotechnical anchors. The founding is deep and it is executed with 181 reinforced concrete pile of dimensions of ø 1.500 mm, l=16, 18 and 20 m, which are arranged in two rows and connected with beam of thickness of 1,2 m and width of 6 m.
The stability of structure K1 is ensured with placing of 361 permanent electrically insulated pre-stressed geotechnical anchors (8Ø15,2 mm), length of l=40 m.
The supporting structures K2 and K3 (of total length of L=569 m) are constructed in the second phase.
They are consisted of two rows of alternately placed reinforced concrete piles Ø=1.500 mm. The piles are designed to be placed at a distance of s=4,50 m. The length of piles on structure K2 is between l=26 and 36 m, and the length of piles on structure K3 is between l=21 and 36 m. It is planned that structure K2 has 161 piles in total, while structure K3 should have 91 piles. The total length of supporting structure K2 is l=363.70 m, while the length of supporting structure K3 is l=205.22 m.
The additional stability of supporting structures K2 and K3 is ensured with permament electrically insulated geotechnical anchors (5Ø15,7 mm).