Editing Geotechnical engineering (section)

=== Offshore ===
{{Main|Offshore geotechnical engineering}}

[[File: Offshore platforms.jpg|thumb|Platforms offshore Mexico.]]
''Offshore'' (or ''marine'') ''geotechnical engineering'' is concerned with foundation design for human-made structures in the [[sea]], away from the [[coast]]line (in opposition to ''onshore'' or ''nearshore'' engineering). [[Oil platform]]s, [[artificial island]]s and [[submarine pipeline]]s are examples of such structures.<ref name="Dean">Dean, E.T.R. (2010). Offshore Geotechnical Engineering – Principles and Practice. Thomas Telford, Reston, VA, 520 p.</ref>

There are a number of significant differences between onshore and offshore geotechnical engineering.<ref name="Dean" /><ref name="Randolph&Gourvenec">Randolph, M. and [[Susan Gourvenec|Gourvenec, S.]], 2011. Offshore geotechnical engineering. Spon Press, N.Y., 550 p.</ref> Notably,  site investigation and ground improvement on the seabed are more expensive; the offshore structures are exposed to a wider range of [[geohazard]]s; and the environmental and financial consequences are higher in case of failure. Offshore structures are exposed to various environmental loads, notably [[wind]], [[wind wave|wave]]s and [[Ocean current|currents]]. These phenomena may affect the integrity or the serviceability of the structure and its foundation during its operational lifespan and need to be taken into account in offshore design.

In [[subsea]] geotechnical engineering, seabed materials are considered a two-phase material composed of rock or [[mineral]] particles and water.<ref name="Das">Das, B.M., 2010. Principles of geotechnical engineering. Cengage Learning, Stamford, 666 p.</ref><ref name="Atkinson">Atkinson, J., 2007. The mechanics of soils and foundations. Taylor & Francis, N.Y., 442 p.</ref>  Structures may be fixed in place in the seabed—as is the case for [[pier]]s, [[jetties]] and fixed-bottom wind turbines—or may comprise a floating structure that remains roughly fixed relative to its geotechnical anchor point. Undersea mooring of human-engineered floating structures include a large number of [[Offshore drilling rig|offshore oil and gas platforms]] and, since 2008, a few [[floating wind turbine]]s. Two common types of engineered design for anchoring floating structures include [[Tension-leg platform|tension-leg]] and [[catenary]] [[Mooring (watercraft)|loose mooring]] systems.<ref name="mit200710">
[http://web.mit.edu/flowlab/pdf/Floating_Offshore_Wind_Turbines.pdf Floating Offshore Wind Turbines: Responses in a Sea state – Pareto Optimal Designs and Economic Assessment], P. Sclavounos et al., October 2007.</ref>