Soft ground challenge for Doha EPBMs 25 Feb 2014
Peter Kenyon, TunnelTalk
After years in the planning, shipment of the first TBM for the Doha Metro project is just weeks away. Peter Kenyon of TunnelTalk was the only member of the international technical industry trade press to attend the handover ceremony of the first machine at the Herrenknecht factory in Schwanau, Germany.
The first of 15 EPBMs for the US$36 billion Doha Metro is formally accepted ahead of disassembly and transportation from the Herrenknecht workshops in Germany to the Red Line South construction job site in the Arab Emirate of Qatar.
7.05m diameter EPBM for Doha Metro

7.05m diameter EPBM for Doha Metro

At a special ceremony at the TBM manufacturer's headquarters in Germany on Monday (24 February) a Qatari delegation headed by the country's Minister for Transport, His Excellency Jassim Saif Ahmed Al Sulaiti, and with officials of project owner Qatar Rail and representatives of the design-build contractor JV team of Qatar Diar/Vinci (QDVC)/Al Darwish Engineering were on hand to celebrate the occasion. QDVC has procured from Herrenknecht all five machines needed for excavation of running tunnels on its Red Line South (RLS) contract.
Also in attendance was former German Chancellor Gerhard Schröder to seal delivery of a project that has had a Made in Germany feel to it, from inception and original design and feasibility studies carried out by German rail operator Deutsche Bahn, through to exclusive procurement of Herrenknecht TBM technology to complete the Qatar Rail Vision of Excellence.
Meanwhile, a second machine for the 16km x 7.05m o.d. twin-running tunnels that comprise the underground element of the contract is currently undergoing final assessment with the client's technical team prior to its official acceptance next week. In the coming weeks and months Herrennecht will deliver three more machines for the contract, as well as four more TBMs for the network's Red Line North (RLN) and six for the Green Line, which represents a clean sweep of all 15 machines for the project thus far for Herrenknecht.
Logistics and scheduling
"We expect to receive the first TBM in Qatar by mid-June," QDVC Project Director Marc Hasenohr told TunnelTalk on the occasion of the ceremonial handover in the Herrenknecht factory Workshop 9. From then on they will arrive at about the rate of one each month until mid-October. After a 10-day journey from the port in Qatar, and an eight-week reassembly period, the first machine for RLS, and indeed the whole project, is due to launch in August or September (2014)," explained Hasenohr. "The RLS tunnels will be ready for handover to Qatar Rail by the end of 2016," he said, well ahead of scheduled completion of the line by 2018.
Presentation party - left to right: Dr Martin Herrenknecht, Chairman, Herrenknecht; Yanick Garillon, CEO QDVC; Adel Abdulrazzaq Haydar, Eng., Chief Operations Officer Manager QDVC; Abdulla Abdulaziz T. Al Subaie, Chairman of Executive Committee Qatar Rail; His Excellency Jassim Saif Ahmed Al Sulaiti, Minister of Transport, State of Qatar; Dr Gerhard Schröder, former Chancellor of Germany, Eng.; Saad Ahmed Al Muhannadi, CEO Qatar Rail, Eng.; Hamad Ibrahim Al Bishri, Deputy CEO/Acting Chief Program Officer; Abdulaziz Nasser Al Nasser, Head of Protocol, Qatar Rail

Presentation party - left to right: Dr Martin Herrenknecht, Chairman, Herrenknecht; Yanick Garillon, CEO QDVC; Adel Abdulrazzaq Haydar, Eng., Chief Operations Officer Manager QDVC; Abdulla Abdulaziz T. Al Subaie, Chairman of Executive Committee Qatar Rail; His Excellency Jassim Saif Ahmed Al Sulaiti, Minister of Transport, State of Qatar; Dr Gerhard Schröder, former Chancellor of Germany, Eng.; Saad Ahmed Al Muhannadi, CEO Qatar Rail, Eng.; Hamad Ibrahim Al Bishri, Deputy CEO/Acting Chief Program Officer; Abdulaziz Nasser Al Nasser, Head of Protocol, Qatar Rail

Logistics for transportation of all 15 machines to Qatar are not yet finalised, but each will be barged on the Rhine in 40 containers from Kehl, north of Schwanau, to the North Sea for onward delivery by sea to Qatar.
Airport City connection
Excavation of the RLS contract is progressing in advance of the two other underground contracts that are also awarded, the Red Line North (RLN), awarded to Impregilo/SK/Galfar; and the Green Line, awarded to Porr/Saudi Binladen/HBK. This is for a strategic reason. The RLS contract also includes early excavation of a short but critical 3.2km-long spur section of the Blue Line that is now packaged into the Phase 1 rather than the Phase 2 programme (Fig 1, black section). Prequalified design-build construction contractors and JVs for the remainder of the semi-circular Blue Line are not yet announced, though this is expected in the coming months.
Fig 1. Doha Metro RLS and Blue Line spur

Fig 1. Doha Metro RLS and Blue Line spur

This section, between Al-Matar Station and the enormous 10km2 development at Airport City, where 200,000 people will eventually live and work, is the location of much of the new hotel, retail and logistics infrastructure that will support Qatar's hosting of the Soccer World Cup tournament in 2022. Packaging the Blue Line spur with the RLS excavation contract will enable an earlier direct connection with the New Doha International Airport (NDIA, also known as Hamad Airport) that is nearing construction completion just to the south. This is also where the underground section of RLS terminates, though it will continue in a mix of elevated and at grade alignments during a later phase of metro development. The Blue Line spur will also enable direct access from Airport City to the Phase 1 metro network to the north (RLN) and west (Green Line), where many of the new stadia are being constructed in a city that is growing daily in preparation for 2022. Qatar Rail Project Director Malcolm Codling explained to TunnelTalk that as the RLS contract included construction of switch boxes to connect it with the future Blue Line towards the Airport City development is was expedient for the contractor to carry on tunnelling the short distance needed to make the connection at this earlier stage.
Eric Fouchault explains TBM design

Eric Fouchault explains TBM design

Machine design
Design of the five TBMs for RLS is based on tackling a predominantly soft-ground geology consisting of limestone and Midra shale. Eric Fouchault, Herrenknecht Project Manager, Traffic Tunnelling, with special responsibility for overseeing design of the RLS machines, told TunnelTalk that a range of machine types had been considered during technical discussions with the QVDC JV, including both EPB and Mixshields. In the end, EPBM technology, capable of working also in open mode, was selected.
"Machine design features eight single cutter disks at the centre of the cutterhead, with 18in x 17in double cutter disks," said Fouchault. "The screw conveyor has a higher than normal installed power of 400kW at the specification of the client. This is somewhat larger than would be expected normally, for a machine of this diameter, but they want to be sure that it can maintain a high rate of advance in open mode. Installed power to the cutterhead is 1,280kW, with the possibility of adding a ninth motor to increase power by a further 160kW."
  • 400kW Screw conveyor

    400kW Screw conveyor

  • Segment erector assembly

    Segment erector assembly

  • Main bearing assembly

    Main bearing assembly

No separate boulder crusher is specified in machine design in line with predicted geological conditions. The machines are expected to operate mostly in open mode, but the zone close to the coast and adjacent to the airport is likely to call for closed mode operation, due to the deeper alignment and higher ground water levels close to the Red Sea.
Malcolm Codling, Project Director for the owner, Qatar Rail, told TunnelTalk: "One of the major issues associated with excavation of the Doha Metro is that it coincides with an enormous amount of simultaneous construction work that is going on all round the city, and the extensive amount of dewatering associated with these projects." This adds to the potential for variable ground water conditions for all the drives, and confirms the choice of EPB technology.
Fig 2. Green Line underground alignment

Fig 2. Green Line underground alignment

Cutterhead fabrication for Green Line TBM

Cutterhead fabrication for Green Line TBM

TBMs under construction for the Green Line

TBMs under construction for the Green Line

"For the Red Line South in particular, another issue is the need to excavate at a deeper level under the new airport runway, which will see the machines operating under higher pressures as a result of the already high groundwater level around the city, but especially so near the coast where it lies only 2m below the surface. Understandably, the owner of the new [US$16 billion] airport is very sensitive to ground movement issues under the runway and terminal buildings of one of Qatar's highest profile construction projects."
Green Line preparations
At the time of the TunnelTalk visit to Herrenknecht, construction of the six machines required for excavation of the 16.6km of east-west twin-running tunnels of the Green (Education City) Line (Fig 2) was also well under way, and delivery of these is expected to begin in the coming weeks and months.
Additionally, Herrenknecht has formed a Qatar-based subsidiary, Herrenknecht Tunnelling SSC, that will operate with a permanent staff of 20 technicians and support staff from a workshop facility of 1,000m2 in the Qatari capital to provide servicing, spare parts and machine support services to the three contracting JVs that are using its TBMs, and in line with its supply contract commitments. "Activity will start in April in anticipation of the arrival of the first machine in June," said Günther Richter of Herrenknecht Traffic Tunnelling. "Each of the three lines will have a separate dedicated team, and in addition to this we are supplying TBM personnel and operators. All spare parts that might be necessary will be available in Doha itself."
Martin Herrenknecht and the Qatar Transport Minister

Martin Herrenknecht and the Qatar Transport Minister

Acceptance ceremony
At the acceptance ceremony itself the Qatari Minister for Transport was assisted in starting up the first project machine by Herrenknecht Chairman, Dr Martin Herrenknecht. At the earlier press conference Abdullah Subaie, Chairman of the Executive Committee of Qatar Rail, said: "Today we have a very important milestone in the Qatar Rail Project. It is driven by desire to achieve the Qatar National Vision by 2030. We have been working on this project in the design and planning for the last five years and today we receive one of the first TBMs. I would like to draw attention to the deep-rooted relationship between Germany and the state of Qatar and today cements this commercial relationship; but the partnership here is not the first one - also we have had one with Deutsche Bahn on the planning and engineering side. This is a very important project for Qatar, and we look forward to inviting you all to be in Doha to break ground with the TBM."
Günther Richter for Herrenknecht said: "The Doha Metro is a challenge for all particpants, the construction companies and also for us here at Herrenknecht, and we are proud that we got the contracts for the delivery of 15 TBMs. Commitment to purchase was made on 20 May (2013) and we started immediately with design and manufacturing and started assembly in the workshop in November. Today you can see the acceptance of the first machine and three other machines that are nearly finished and will have their acceptances in May and June. We will start on assembly on this first machine in Doha at the beginning of June where hopefully it will be ready to bore at the end of July or August this year."
References
Herrenknecht sweeps Doha Metro Phase 1 - TunnelTalk, January 2014
Doha rolls out metro contracts - TunnelTalk, June 2013
Qatar begins Doha metro tunnel awards - TunnelTalk, April 2013
Doha progresses to metro construction - TunnelTalk, August 2012
Qatar drives forward with Doha Metro - TunnelTalk, December 2011

           

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