Tunneling is an intricate and essential aspect of modern construction. It encompasses a multitude of methods that facilitate the excavation and construction of underground passages.
Here are the prominent tunneling methods that have become an integral part of the tunnel industry:
Primarily used for shallow tunnels, the cut-and-cover method involves excavating a trench, constructing the tunnel within it, and subsequently covering it with backfill material. It is commonly employed in urban areas for the creation of infrastructure such as roadways, subway systems, and utility tunnels.
Widely utilized in rock formations, this method entails drilling holes into the rock face, placing explosives, and carefully blasting the rock to create a void space. Subsequently, the excavated material is removed, and support systems are installed. Drill and blast offer versatility, making it suitable for tunnels in varying ground conditions.
TBMs have revolutionized tunneling, especially in soft ground conditions. These advanced machines excavate tunnels by simultaneously drilling, cutting, and removing the soil or rock. TBMs increase efficiency, minimize ground settlement, and are well-suited for longer tunnels.
Also known as the New Austrian Tunneling Method (NATM), SEM involves the systematic excavation of tunnels using temporary support systems. The method adapts to changing geological conditions by allowing engineers to modify the tunnel support as excavation progresses.
Often employed in urban areas with soft ground conditions, shield tunneling utilizes a shield machine to excavate the tunnel while simultaneously installing a precast concrete lining. This method ensures minimal surface disruption and is commonly used for subway systems, underground railways, and utility tunnels.
Applied to underwater tunnel construction, this method involves prefabricating tunnel sections, known as immersed tubes, in a dry dock. These sections are then floated to the site, submerged, and joined together, forming the tunnel structure. Immersed tube tunnels are commonly used for underwater crossings, such as river or estuary crossings.