March 2017.- Whether in the east, west, north or south, global tunnelling and underground development – worth $100bn annually – remains a buoyant and dynamic sector. And more growth could be expected with increasing needs for mining applications and rising urban populations leading municipalities to seek underground solutions.
2016 seems to be a particularly record-breaking year: the recent opening of the Gotthard Tunnel (11th of December) through the Alps in Switzerland exemplifies the outstanding size of projects launched and completed to date. Even though the activity has historically been very strong in Europe and North America, new trends have emerged in the past few years: nowadays, almost 60% of tunnelling projects are located in Asia, 29 cities in China are currently extending or building their metro. Also, the place of South America is globally rising in the Tunnelling industry.
Global overview of projects underway in the world:
Overview in Asia:
- The Deep Tunnel Sewerage System, Singapore
- The Jurong Rock Caverns, Singapore
- Thomson East Coast Line, Singapore
- The New Guanjiao Tunnel, China
- Xi’an, Shenzen, Shanghai, Chengdu metro extensions, China
- Wan Chai Bypass, Hong Kong, China
- Klang Valley, Kuala Lumpur- Malaysia
- Mumbai, Kolkata, Dehli metro, India
- Zojila tunnel, India
- Teheran-Mazandaran highway, Iran
- Gaoligongshan Railway Tunnel, China
- Muzailing Railway Tunnel, China
- Hong Kong-Zhuhai-Macau Highway Immersed Tunnel, China
- Que’ ershan Highway Tunnel, China
Overview in South America:
- Opening Metro Line 4 in Rio, Brasil
- Sarmiento railway, Argentina
- Duplications of Joa and Pepino Tunnels, Brasil
- Agua Negra road tunnel, Argentina-Chile
- Toya tunnel, Colombia
Overview in North America :
- California Fix Water Program, USA
- Seattle Alaskan Way, USA
- New York 2nd Avenue, USA
- Metro Vancouver, Canada
- Coxwell bypass Toronto, Canada
Overview in Europe :
- The Grand Paris Project, France
- Norway’s Ryfast scheme, Norway
- Venda Nova Project, Portugal
- Brenner Tunnel, Austria-Italy
- Thames Tideway Tunnel, UK
- Swina tunnel, Poland
A healthy dynamic exemplified by 5 on-going projects:
- The Grand Paris Express Project
A typical example of the latter is the Grand Paris Express project – a truly ambitious expansion of the French capital’s metro network designed to connect central areas with the outer suburbs.
Around 205km of new line and 72 stations will be completed in phases through to 2030.
The project will involve the construction of 4 new, fully automated metro lines (Nos 15, 16, 17 and 18) and the extension of two existing lines (11 and 14).
Line 15 will be entirely underground and will comprise the excavation of 75km of tunnels; Line 16 will be 25km long, including 5.5km in common with Line 17 which will be 27km long and have 9 stations, while the 35km-long Line 18 will have 10 new stations.
The majority of the tunnels will be TBM-bored through Paris basin sediments at depths of between 15-55m below the surface and advancing at rates of 10-12m/day. Up to seven TBMs will work simultaneously on Line 15 with spoil transported down the Seine. Five machines will work simultaneously on Nos 16, 17 and 14 with spoil transported down the Saint Denis canal. Work began in 2015 on line 14 and preliminary works on lines 15 and 16 in 2016.
- Norway’s Ryfast scheme
Another on-going European mega-project is Norway’s US$ 1bn Ryfast scheme. Involving a total 23.9 km of drill and blast tunnelling in and around Stavangar, the project involves four large tunnel contracts, including the excavation of the world’s longest subsea dual-carriageway road tunnel at 290m below sea level – Norway’s deepest and steepest subsea tunnel. Completion is expected in 2019. Parts of the project will also be the focus of post-conference tours for WTC 2017 delegates, as will seeing the TBM drives in Oslo for the Follo Line rail project.
- California’s WaterFix Programme
California’s largest supply of clean water is dependent on 50-year-old levees. Earthquakes, floods and rising sea levels could cause these levees to fail, putting fresh water supply at risk from saltwater contamination. California’s US$15bn Water Fix Programme (formerly Bay Delta Conservation Plan) aims to upgrade the water conveyance network in the Sacramento-San Joaquin Delta region. Large diameter tunnels will convey up to 255m3/sec of water from the Sacramento River to major pumping stations in the south.
The programme comprises three river intake structures, around 16km of 8.8m- and 12.2m-ID tunnels, and approximately 96km of 12.2m ID main conveyance tunnels with inverts at around 46m below ground level. Tunnel design should commence in mid-2018 with the new water infrastructure expected to be operational by 2033.
- Jurong Rock Caverns in Singapore
Hailed as Southeast Asia’s ﬁrst storage caverns for crude oil and other liquid hydrocarbons, Singapore’s Jurong Rock Caverns were recently recognised in the ITA’s 2016 Tunnelling Awards as winner in the Innovative Use of Underground Space category. The 150m-deep underground caverns are located in mainly siltstones and sandstones below the seabed at Banyan Basin and have a storage capacity of 1.47million m3 of liquids, saving around 60ha of surface space. Oil is retained in the caverns by hydrostatic pressure keeps the oil in the caverns. Any water that seeps in is pumped out automatically.
The project comprises four unlined caverns, of lengths between 270 and 340m, with a typical cross-section of around 20m wide and 27m high. But the complex also features a host of ancillary tunnels including connecting tunnels from start-up galleries, operations tunnels and access tunnels.
The two access shafts have a 24m diameter and were constructed with 1m-thick diaphragm walls and ring beams. Excavation throughout was by drill and blast with pre-grouting to reduce seepage. The complex was completed in Q1 2017.
- Underground Works for flood control at Grande Tijuca and Maracanã
The Rio Olympics are long over, but the infrastructure legacy built to help the city stage the games, such as Metro Line 4, and especially the tunnelling legacy, have helped the city relieve its traffic congestion crisis. Tunnels have also helped in other sectors. The Mangue district, home to the iconic Maracanã stadium, is drained by five rivers and has been plagued by summer rainstorms causing flash flooding. As a result, a large-scale £300 million underground works scheme was instigated to control the problem.
A variety of flood control works have been constructed including five new deep detention reservoirs, a new 2•4 km-long river diversion tunnel and the enlargement of an existing 1•8 km-long culvert. In addition, the city’s new operation and control centre monitors all river flows.