5. Rubble Mound Structures
183
the structure of one nominal diameter Dn. An extension of the subscript in
No can give the distinction between displaced out of the layer, units rocking
within the layer (only once or more times). The actual number is related
to a width of one Dn.
Nod = units displaced out of the armour layer (hydraulic damage)
Nor = rocking units and
Nomov = Nod + NOr5.7.2
Number of units method
This method damage assessment follows the procedure of Owen and Allsop
[1983]. The damage to the groin section is in terms of the number of armour
units, which hâve been totally dislodged from the armour layer. This can be
expressed as a percentage of the total number of units on the armour layer.
The movement of armour units can assess the damage and four categories
of armour unit movements are given below:
• P — Unit seen to be rocking, but not permanently displaced.
• Q — Unit displaced by up to 0.5D
• R — Unit displaced between 0.5 and 1.0D
• S — Unit displaced by more than 1.0D
where, D is the équivalent diameter of an individual armour unit. The order
of damage for armour layer has been assessed using the formula,
M
,
Number of armour units dislodged
% of damage = -— ------7------------ ;—;----------- y------x 100
Total number of umts m armour layer
The total is P+Q+R+S which it is less than 5%, the section is accepted
to be safe. For the breakwater sections, the assessment of damage by the
number of units method was adopted, in which case, the units are continuously monitored during the propagation of waves over the CAU. The
study on the stability of breakwater sections and their analysis was based
on visual observations of its physical behaviour. As stated in this section,
the number of units’ method is adopted for assessing damage of the rubble
mound sections.
A view of the breakwater after establishing its Kd in the Laboratory in
Department of Océan Engineering in Krishnapatnam port situated along
the east coast of India (14°15'N, 80°08'E) is projected in Fig. 5.14.
183
the structure of one nominal diameter Dn. An extension of the subscript in
No can give the distinction between displaced out of the layer, units rocking
within the layer (only once or more times). The actual number is related
to a width of one Dn.
Nod = units displaced out of the armour layer (hydraulic damage)
Nor = rocking units and
Nomov = Nod + NOr5.7.2
Number of units method
This method damage assessment follows the procedure of Owen and Allsop
[1983]. The damage to the groin section is in terms of the number of armour
units, which hâve been totally dislodged from the armour layer. This can be
expressed as a percentage of the total number of units on the armour layer.
The movement of armour units can assess the damage and four categories
of armour unit movements are given below:
• P — Unit seen to be rocking, but not permanently displaced.
• Q — Unit displaced by up to 0.5D
• R — Unit displaced between 0.5 and 1.0D
• S — Unit displaced by more than 1.0D
where, D is the équivalent diameter of an individual armour unit. The order
of damage for armour layer has been assessed using the formula,
M
,
Number of armour units dislodged
% of damage = -— ------7------------ ;—;----------- y------x 100
Total number of umts m armour layer
The total is P+Q+R+S which it is less than 5%, the section is accepted
to be safe. For the breakwater sections, the assessment of damage by the
number of units method was adopted, in which case, the units are continuously monitored during the propagation of waves over the CAU. The
study on the stability of breakwater sections and their analysis was based
on visual observations of its physical behaviour. As stated in this section,
the number of units’ method is adopted for assessing damage of the rubble
mound sections.
A view of the breakwater after establishing its Kd in the Laboratory in
Department of Océan Engineering in Krishnapatnam port situated along
the east coast of India (14°15'N, 80°08'E) is projected in Fig. 5.14.