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In addition to resource abundance, deep-sea mining benefits from high-grade deposits and lower operational costs compared to terrestrial mining due to reduced overburden removal. Optimizations such as reduced trench depth can cut mining time by 26% and increase deposit value by 53%. [138]
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.
The risk of cave-in increases from surcharge load, which is any weight placed outside the trench near its edge. These loads include the spoil pile (soil excavated from the trench) or heavy equipment. These add extra stress to the walls of the trench. Inability to escape the trench because of steep and unstable walls, which may be difficult to ...
Deterioration to water quality; Increase in the cost of water to the consumer due to a lower water table—more energy is needed to pump from a greater depth, so operating costs increase for companies, who pass on the expense to the consumer; Decrease in crop production from lack of water; Disturbances to the water cycle
Large amounts of water used for mine drainage, mine cooling, aqueous extraction and other mining processes increases the potential for these chemicals to contaminate ground and surface water. As mining produces copious amounts of waste water, disposal methods are limited due to contaminates within the waste water.
Excavation may be classified by type of material: [1]: 13.1 Topsoil excavation; Earth excavation; Rock excavation; Muck excavation – this usually contains excess water and unsuitable soil; Unclassified excavation – this is any combination of material types; Excavation may be classified by the purpose: [1]: 13.1, 13.2
The main advantage of an immersed tube is that they can be considerably more cost effective than alternative options – i.e., a bored tunnel beneath the water being crossed (if indeed this is possible at all due to other factors such as the geology and seismic activity) or a bridge. Other advantages relative to these alternatives include:
In subsea geotechnical engineering, seabed materials are considered a two-phase material composed of rock or mineral particles and water. [ 18 ] [ 19 ] Structures may be fixed in place in the seabed—as is the case for piers , jetties and fixed-bottom wind turbines—or may comprise a floating structure that remains roughly fixed relative to ...