TBM Karpatka will excavate a two-lane 2.2km tunnel between Rzeszów Południe and Babica. The Acciona and Mostostal Warszawa consortium will also construct 15 cross-passages and an emergency passage, two technical buildings and a tunnel management centre.
The TBM, which weighs 4,000 tons, is 112m long and has a diameter of more than 15m, will work at a maximum depth of 100m under the Grochowiczna hill. The tunnel is part of a new 10.3km section of road.
The machine has been refurbished to meet the challenges of what is considered one of the most technologically advanced infrastructure projects in the country. The upgrade includes a geological prediction tool that allows data to be collected from the tunnel face without the need for drilling.
“I am pleased to confirm that after adapting the TBM machine for potential methane conditions, the tunnelling process has started and is safe” said Jorge Calabuig Ferre, vice-president of Mostostal Warszawa.
In July last year, gas was detected during test pumping to lower the water table for tunnelling. Methane appeared in two of the 44 well holes.
A team of specialists from the contractor and client, along with experts from the AGH University of Science and Technology in Krakow, the Higher Mining Authority in Katowice, and the District Mining Office in Krosno, worked on addressing the issue.
To prepare the TBM for methane conditions, mining experts required the installation of methane detection sensors and a modified, high-efficiency ventilation system to prevent gas accumulation. Parts of the machine were also replaced with equipment suitable for methane conditions.
The tunnel segments are being produced at the construction site in Lutoryż. The production facility houses four cranes – the largest with a 60-ton capacity – and a concrete plant. More than 2,230 rings will be used for the tunnel lining.
The TBM is expected to complete the first bore in around nine months. It will then take around three months to turn the machine for it to begin drilling the second lane of the tunnel.
