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Chapter 1
Scour Around Marine Structures
7.1 Introduction
Scour around structures is one of the major problems, often dictating their
stability in the Coastal and offshore environments. Scour is simply the
removal of sédiment particles in the vicinity of any obstruction due to the
flow of water. Scour, for a layman, is simply the érosion of bed material due
to a solid obstruction for the flow of water of océan or a river. This phenomena can be experienced when one stands on the beach and is exposed
to the return flow of waves that results in removal of sand around the feet.
It is due to the interaction between an obstacles to the fluid flow field. As a
matter of fact, ail these processes interact with one another, which makes
the process of scour very complex.
Scour occurs where, the sédiments get eroded from the seabed under the
influence of waves and currents. Scour nearby a structure can be attributed
to the localized divergence in the sédiment transport rate in the vicinity
of the structure, thereby lowering the existing bed level. Ail the offshore
structures require support from the océan bed in the form of footings or raft
or anchors or piles. When a foreign object is placed on the seabed, the flow
pattern changes around the structure and érosion of the bed takes place.
The scour will be more if the structure in an area of loose sand or when it
is exposed to high velocity current. It can even cause the tilting of gravity
structures. In the case of piles, it reduces the depth of fixity, which in turn,
reduces the latéral load carrying capacity of the pile and the overburden
pressure. Scour also causes problems in the case of structures like navigational structures and pipelines. Scour mainly dépends on geometry of the
structure, hydraulic parameters of flow and the sédiment characteristics of
seabed.
Chapter 1
Scour Around Marine Structures
7.1 Introduction
Scour around structures is one of the major problems, often dictating their
stability in the Coastal and offshore environments. Scour is simply the
removal of sédiment particles in the vicinity of any obstruction due to the
flow of water. Scour, for a layman, is simply the érosion of bed material due
to a solid obstruction for the flow of water of océan or a river. This phenomena can be experienced when one stands on the beach and is exposed
to the return flow of waves that results in removal of sand around the feet.
It is due to the interaction between an obstacles to the fluid flow field. As a
matter of fact, ail these processes interact with one another, which makes
the process of scour very complex.
Scour occurs where, the sédiments get eroded from the seabed under the
influence of waves and currents. Scour nearby a structure can be attributed
to the localized divergence in the sédiment transport rate in the vicinity
of the structure, thereby lowering the existing bed level. Ail the offshore
structures require support from the océan bed in the form of footings or raft
or anchors or piles. When a foreign object is placed on the seabed, the flow
pattern changes around the structure and érosion of the bed takes place.
The scour will be more if the structure in an area of loose sand or when it
is exposed to high velocity current. It can even cause the tilting of gravity
structures. In the case of piles, it reduces the depth of fixity, which in turn,
reduces the latéral load carrying capacity of the pile and the overburden
pressure. Scour also causes problems in the case of structures like navigational structures and pipelines. Scour mainly dépends on geometry of the
structure, hydraulic parameters of flow and the sédiment characteristics of
seabed.