+387 (0)51 337 401
  • YouTube
  • YouTube

Headrace tunnel for HPP Dabar: Active preparations for new phase of works

Feb 19, 2021

After the tunnel was cut through the excavation point 3 and excavation point 4 on July 26, 2020, the excavation of tunnel between the excavation point 1 and excavation point 2 continued. At this moment, the total continuously excavated length of tunnel pipe is l=10,797.5 m, while the length of l=1,427.5 m remains for excavation.

Due to the advanced phase of works on the excavation of tunnel pipe, intensive preparations for construction of its reinforced concrete lining are in progress, which represents a new phase of works on this project.

In connection with that, two sets of metal hydraulic formworks for the construction of secondary lining of tunnel were purchased from the manufacturer “CEKA” (Ankara, Turkey). Each formwork set of length of l=12 m, consists of two parts: (1) the formwork of the foot vault and (2) the formwork of the upper arch vault – “calotte”.

The delivery of formwork to the tunnel construction site by special oversized vehicles is in progress.

Upon arrival of all elements, the formwork will be completed at the location of Vodostan (tunnel exit portal), after which the installed formwork will be “pulled” into the tunnel. The initial position of secondary lining construction is about 4 km away from the portal. Transport of the formwork to the starting position will be performed by a company specialized in this type of work. Low-bed trailers that can be operated from both ends will be used for transport. In the first step, one formwork of the foot vault will be transported, with which three to four sections will be constructed. In the next steps, two calottes will moved into the tunnel, as well as the second formwork of the foot vault. In this way, the secondary lining will be constructed in two directions simultaneously (towards the entrance and exit side of the tunnel) in sections of l=12 m each, which means that it will be necessary to perform slightly more than 1,000 sections (moving the formwork).

The new phase of works will require the placing of a significantly larger amount of concrete than before, which is the reason that, in addition to the existing concrete plant “Simem” Eagle 2500 Star of capacity of 80 m3/h, a new concrete plant “Semix” Turkmobil 100S4 of capacity of 100m3/h, was purchased and delivered to the tunnel site.

We expect that these two concrete plants, together with the mobile crushing plant, will fully meet the needs for the secondary lining of headrace tunnel of HPP Dabar in the length of l=12,125.00 m, as well as possible future needs for concrete in the construction of HPP Dabar and other structures in the system “Gornji horizonti”.

Due to the usually high waters during winter period, the works on the construction of the entrance structure through which the water from the accumulation “Pošćenje” will be introduced into the headrace tunnel are interrupted and they will be continued after water withdraw.

Due to the advanced phase of works on the excavation of tunnel pipe, intensive preparations for construction of its reinforced concrete lining are in progress, which represents a new phase of works on this project.

In connection with that, two sets of metal hydraulic formworks for the construction of secondary lining of tunnel were purchased from the manufacturer “CEKA” (Ankara, Turkey). Each formwork set of length of l=12 m, consists of two parts: (1) the formwork of the foot vault and (2) the formwork of the upper arch vault – “calotte”.

The delivery of formwork to the tunnel construction site by special oversized vehicles is in progress.

Upon arrival of all elements, the formwork will be completed at the location of Vodostan (tunnel exit portal), after which the installed formwork will be “pulled” into the tunnel. The initial position of secondary lining construction is about 4 km away from the portal. Transport of the formwork to the starting position will be performed by a company specialized in this type of work. Low-bed trailers that can be operated from both ends will be used for transport. In the first step, one formwork of the foot vault will be transported, with which three to four sections will be constructed. In the next steps, two calottes will moved into the tunnel, as well as the second formwork of the foot vault. In this way, the secondary lining will be constructed in two directions simultaneously (towards the entrance and exit side of the tunnel) in sections of l=12 m each, which means that it will be necessary to perform slightly more than 1,000 sections (moving the formwork).

The new phase of works will require the placing of a significantly larger amount of concrete than before, which is the reason that, in addition to the existing concrete plant “Simem” Eagle 2500 Star of capacity of 80 m3/h, a new concrete plant “Semix” Turkmobil 100S4 of capacity of 100m3/h, was purchased and delivered to the tunnel site.

We expect that these two concrete plants, together with the mobile crushing plant, will fully meet the needs for the secondary lining of headrace tunnel of HPP Dabar in the length of l=12,125.00 m, as well as possible future needs for concrete in the construction of HPP Dabar and other structures in the system “Gornji horizonti”.

Due to the usually high waters during winter period, the works on the construction of the entrance structure through which the water from the accumulation “Pošćenje” will be introduced into the headrace tunnel are interrupted and they will be continued after water withdraw.

Video: Breaktrough between excavation points NM3 and NM4

 

 

U cilju prevencije od COVID-a 19 molimo Vas da se pridržavate propisanih i preporučenih mjera zaštite. Održavajte distancu, nosite masku i redovno perite ruke!