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Tunnel Construction. Tunnels are dug in types of materials varying from soft clay to hard rock. The method of tunnel construction depends on such factors as the ground conditions, the ground water conditions, the length and diameter of the tunnel drive, the depth of the tunnel, the logistics of supporting the tunnel excavation, the final use and shape of the tunnel and appropriate risk management.
Cut-and-cover construction at Saint-Michel on Paris Métro Line 4 (c. 1910) Cut-and-cover is a simple method of construction for shallow tunnels where a trench is excavated and roofed over with an overhead support system strong enough to carry the load of what is to be built above the tunnel. [29] There are two basic forms of cut-and-cover ...
Excavation of the tunnel began in May 1999; the cut and cover method was used. [24] The nine homes were demolished and a 2,900-foot (880 m) trench was dug down to 35 feet (11 m) deep. [43] A total 160,000 cubic yards (120,000 m 3) of dirt were removed, [24] most of which was reused to construct ramps at other sites on the connector. [44]
Deep level underground is construction that is 20 m (66 ft) or more below ground and not using the cut-and-cover method, especially train stations, air raid shelters and bunkers, and some tunnels and mines. Cut-and-cover is a simple method of construction for shallow tunnels where a trench is excavated and roofed over with an overhead support ...
A slurry wall is a civil engineering technique used to build reinforced concrete walls in areas of soft earth close to open water, or with a high groundwater table. [1] This technique is typically used to build diaphragm (water-blocking) walls surrounding tunnels and open cuts, and to lay foundations.
Underground construction has a number of unique risks and challenges but shares a lot with traditional construction and mining. Underground construction workers often work under reduced light condition, in dangerous spaces, and are at a high risk of exposure to contaminants, fire, and explosions.
The new Austrian tunneling method (NATM), also known as the sequential excavation method (SEM) or sprayed concrete lining method [1] (SCL), is a method of modern tunnel design and construction employing sophisticated monitoring to optimize various wall reinforcement techniques based on the type of rock encountered as tunneling progresses.
Deep bore tunneling methods were to be used in order to avoid the disruptions for road traffic, pedestrians, utilities and local businesses produced by cut-and-cover methods of past generations. Stations were to retain cut-and-cover construction. [3] [60] The total cost of the 8.5-mile (13.7 km) line is expected to exceed $17 billion. [38]