Travel times of over two hours are daily routine for Moscow’s commuters. With a growing population of nearly 12 million, the Moscow Government has issued an extensive city-wide metro project, totaling 50 km (31 mi) of new track by 2018.
A total of five Robbins EPBs have bored multiple tunnel drives on the Moscow Metro. Combined, the EPBs have bored more than 8km of tunnel.
All TBMs have been custom designed to handle the area’s complex geology of fine sand, gravel, sandy loam, stiff clays and limestone. Each TBM is equipped with a mixed ground cutterhead capable of switching out carbide cutting tools with disc cutters, depending on conditions.
Besides their mixed ground capabilities, each EPB will utilize a Robbins continuous conveyor system for maximum efficiency during muck removal. Surface monitoring devices will also be employed to limit settlement due to the project’s densely urban environment in the heart of Moscow.
These machines are the first to use electric variable frequency drives (VFDs) in Moscow. The high thrust and torque capabilities of the machines allow for faster excavation while minimizing disturbance that can lead to surface settlement. Active articulation on the machines enables them to excavate tighter curves without the risk of segment deformation that is present when using passive articulation.
Tunneling occurred at dozens of compact jobsites characterized by Moscow’s challenging mixed ground conditions. Three new Robbins High Performance EPBs and one refurbished machine, named “Julia” operated in various areas of the city. The machines were customized to excavate in the city’s difficult mixed ground geology.
Three Robbins EPB machines were contracted under Engeocom; two 6.6 m diameter machines excavated left and right-hand tunnels, each 1.8 km in length, and “Julia” excavated a 2 km section of a tunnel. A fourth machine contracted under USK MOST is a 6.2 m diameter machine with mixed ground cutterhead that bored a 1.9 km section of a tunnel. All four Robbins machines have also utilized Robbins continuous conveyors for the mixed ground conditions.
When the fourth Robbins machine was launched in winter 2012 from a 15 m deep shaft, contractor USK MOST needed to bore through ground conditions consisting of dense clay and fine sand. They used foam and conditioner to keep the earth balanced, and ultimately for easier muck removal. Not only were they able to keep up with the project’s challenges, but the machine also achieved milestone rates of 150 m in one week, and up to 500 m per month in spring 2013. Experienced crew members, a rigorous schedule, implementation of the continuous conveyor, and the reliability of the Robbins TBM are all factors that helped achieve the record.
The Robbins EPB for USK MOST made its breakthrough on May 24, 2013. City officials and contractors celebrated not only a record-breaking achievement for the 6.2 m (20.3 ft) diameter mixed ground machine but also finishing ahead of schedule. The TBM achieved a 37.8 m (124 ft) advance in one day at the end of April 2013 – a Russian record for EPBs in the 6 to 7 m (20 to 23 ft) diameter range.
In 2015, a fifth Robbins EPB was added to the mix. The machine was assembled using Onsite First Time Assembly (OFTA) for contractor Evrascon. It bored 4 km of tunnel in hard clay, sand, gravel, pebbles, hard limestone with water, and loam, breaking through in May 2016.
On October 24, 2015, another milestone was reached at the Moscow Metro. A 6.65 m (21.8 ft) diameter Robbins EPB completed its second tunnel, measuring 2.5 km (1.6 mi). The TBM made a breakthrough at its first 2.1 km (1.3 mi) long tunnel drive in January 2014. Contractor SMU Engeocom plans to use the machine on a third tunnel—and that will not be the first time that an EPB has been used on multiple drives at Moscow Metro. Engeocom owns another 6.65 m (21.8 ft) Robbins EPB that completed its second tunnel at the end of September 2015, and will also go on to bore extra tunnels.
On February 01, 2017 the record-setting Robbins EPB originally for USK MOST started excavation of its fourth bore on the Moscow Metro Project. Its new tunnel will be about 2 km long and will connect stations “Kosino” and “Ulitsa Dmitrievskogo” on the new “Kozhukhovskaya” metro line. The geology is very difficult in this area and running sands are expected. In addition the machine will drive under existing railway tracks. The machine is currently owned by MIP-Story #1 Company—an affiliate of Mosinzhproekt – Main Contractor and Design Institute on the Moscow Metro Project.
The robust Robbins EPBs are capable of even more mixed ground tunnels for the Moscow Metro.