Page 9 - TunnelTalk Annual Review 2017

From left: Fig 1. Dubai Metro Expo 2020 extension; Storm water drainage and build out of sewer infrastructure
DTubai destination for WTC2018 delegates
he Middle East has been a hotspot of will serve the catchment areas of Deira and TunnelTalk reporting world tunnelling over recent decades Bur Dubai with one main tunnel collector
with a wealth of new underground transferring flow from the Bur Dubai region (STEP) sewer tunnel network in Abu Dhabi.
infrastructure planned in the region in the coming years. A spotlight on this activity will be presented in April 2018 when the Tunnelling Chapter of the Society of Engineers of the United Arab Emirates (UAE) hosts the ITA World Tunnel Congress (WTC).
In Dubai new infrastructure is being built in preparation for the city’s hosting of the World Expo in 2020.
For the metro there is a 15km extension of the Red Line to the Expo 2020 site with 10.5km on elevated trackway and 4km and two stations aligned underground (Fig 1). Under a US$2.9 billion contract, the Expolink Consortium of Alstom, France/ Acciona, Spain/Gulermack, Turkey will complete the works and supply 50 trains for the extension and to upgrade rolling stock on the existing metro network. A 10m diameter HerrenknechtEPBMisexcavatingthesingle tube, double track running tunnel of the project. The Line will be extended further to the site of the new international airport for Dubai, which is currently in construction. Once complete, the total network of Dubai Metro will be 90km.
Also for Expo 2020, Dubai is building a network of two deep stormwater tunnels. The main 12km long Jebel Ali stormwater tunnel package was awarded to a joint venture of Porr, Austria and Besix, Belgium. The second major tunnel package through Deira, beneath Dubai International Airport, is currently in the tender stage. With the storm water tunnels at up to 10m i.d. there are plans that parts of these could be designed as dual mode facilities with road decks built into the internal space and closed to traffic in times of heavy rainfall when the full capacity of the stormwater management facility is needed. The proposal is based on the first use of the concept for the SMART tunnel in Kuala Lumpur, Malaysia.
Further to the storm drainage tunnels, there are plans in Dubai for a Strategic Sewer Tunnel Project with a combined length of 70km and a further 140km of link sewers and pumping stations. The system
to a treatment plant at Jebel Ali, and the other conveying flow from the Deira and Dubai International Airport area to a treatment plant at Al Warsan (Figs 2 and 3).
Also in the Emirate of Dubai, international contractors were invited in 2017 to submit expressions of interest to bid for the Hatta pumped storage project. The 250MW project for the Dubai Electricity & Water Authority is to be built as an engineering, procurement and construction (EPC) contract. French energy utility EDF was awarded a consultancy contract in mid-2017 to manage design, procurement and supervision of the project.
DEWA plans to create the Hatta pumped storage project by using the existing Sadd Hatta Al Awwal reservoir on Wadi Zahra as the lower reservoir and create a new upper reservoir in the Hajar Mountains to provide a gross head of 300m. Tunnelling works on the project will involve excavation of a pressure tunnel, pressure shaft and surge tank through peridotite rocks. The project is part of the Emirates Dubai Clean Energy Strategy 2050, which seeks to have three-quarters of the energy mix for Dubai provided by clean energy by 2050.
Further afield, but in the same Middle East region, the Abu Hamour drainage tunnel in Doha, Qatar was recognised as a first class tunnel project. Designed by COWI and constructed by Salini Impregilo, the 9.5km long x 3.7m diameter storm water tunnel runs along the route of the proposed F-Ring Road from Musaimeer Street to the New Doha International Airport and will convey water flows of up to 16.5m3/sec.
Being located in a hot and humid environment with a high concentration of chlorides and sulphates in the soil and groundwater, the tunnel required a highly durable lining to achieve the specified design life of 100 years. This was met by using a steel fibre reinforced concrete (SFRC) segmental lining. COWI first designed a SFRC segmental lining for the Strategic Tunnel Enhancement Programme
In Lebanon, in May 2017, a CREG 3.5m diameter gripper TBM made its first breakthrough on Tunnel Drive 3 of the Greater Beirut Water Supply Project. Financed by the World Bank, the project is scheduled to be in operation by 2019 to supply drinking water to 1.6 million people in the region and involves construction of 24km of tunnels and transfer pipelines. The contract was awarded to CMC di Ravenna of Italy by the Council for Beirut Development and Reconstruction in 2014. The tunnels are being excavated by two CREG hard rock gripper TBMs through weathered limestone, dolomitic limestone and dolomitite rock with strengthsofbetween50-170MPa.
After completing the 4.13km Tunnel Drive 3, the first TBM will bore the 8.10km Tunnel Drive 1. The second TBM, launched in September 2016, completing the 10.37km Tunnel Drive 2.
The first TBM on Tunnel Drive 3 encountered faults and highly fractured rock which slowed excavation. Despite difficulties, the TBM achieved average rates of 18m/ day, with a maximum of 48.22m/day and a monthly rate of 894.8m/month.
The theme of the WTC Congress in April 2018 is The Role of Underground Space in Future Sustainable Cities and topics discussed will include:
• Multi-utility tunnels – The ultimate solution • Win/win contractual risk sharing
• Selecting the right tunnelling method
• Maintenance-free design in sewer
tunnels – fact or fiction
• CAPEX vs OPEX – how to define life
cycle project cost
• Sustainable use of underground space • Underground contribution to Smart Cities • Life safety for underground structures
The World Tunnel Congress will also convene the 44th General Assembly of the ITA International Tunnelling and Underground Space Association. The UAE was welcomed asanITAMemberNationin2011andisfirst to host the World Tunnel Congress in the GCC (Gulf Cooperation Council) region. n
From left: Hatta pumped storage plans; SRFC segmental lining in Doha; TBM breakthrough in Lebanon
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