SK Most subsidiary OJSC Bamtonnelstroy completed a 4.5km stretch of tunnel on the Sochi project this month. The project was part of the infrastructure vision for the Sochi 2014 Winter Olympics.
The 6.2m Robbins Double Shield TBM encountered difficult ground, advancing with average rates of 100-120m per week.
The 6.2m TBM achieved high rates despite difficult conditions. The alignments ran through mixed ground including massive to completely fractured limestone with clay seams. Some sedimentary rock including sandstone and siltstone was encountered, along with fault zones consisting of breccias and conglomerates.
“In May 2010, the machine was stopped after encountering a significant fault zone consisting of broken rock and running soft ground,” said Robbins.
“Field service personnel and crew successfully freed the machine by excavating a bypass tunnel around the TBM, freeing the cutterhead. Following the restart, a combination of continuous probe drilling and ground treatment with cement silicate and foam kept the machine moving forward.”
A 10m TBM was still excavating the parallel 4.6km main railway tunnel, 762m into the drive as T&TI went to press, and a 13.2m diameter road tunnel was also under construction. A continuous conveyor system was used on the main tunnel for efficient muck removal.
Over 20 road and rail tunnels stretching for 40km are under construction for the Sochi Games. Project owner DCRC-Sochi, a subsidiary of Russian Railways, hopes to complete all rail and road infrastructure by June 2013.
