3506
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
0
2
4
6
8
10
12
0
500
1000
1500
2000
2500
3000
Time [s]
Excess pore pressure [N/m
2
]
0
2
4
6
8
10
12
14
-1
0
1
2
3
4
5
6
Experimental
Numerical
A
Figure 5. Numerical and experimental excess pore pressure obtain under
the shoreward caisson edge induced by two impulsive wave actions
(
H=0.6m, T=6.5s, h
s
=1.6m, h
1
=0.6m
).
The proposed model is also able to reproduce satisfactorily
the accumulative settlement behaviour of a vertical breakwater
structure subjected to series of sea wave impacts, eventually
leading to a diffuse failure mechanism. It is also able to simulate
adequately the correlation between accumulated settlements and
residual pore pressure (Figure 6).
0 20 40 60 80 100 120 140 160 180 200
-6
-4
-2
0 x 10
-3
Time [s]
Vertical
Displacement [m]
0
20
40
60
80
100
120
0
2000
4000
Time [s]
Excess
pore pressure [N/m
2
]
0
2
4
6
8
10
12
14
-1
0
1
2
3
4
5
6
0
2
4
6
8
10
12
14
-1
0
1
2
3
4
5
6
A
A
A
A
Figure 6. Relation between accumulated settlement and residual pore
pressure (
H=0.6m, T=6.5s, h
s
=1.6m, h
1
=0.6m
). Numerical result
The relation shown in Figure 6 indicates a residual pore
pressure directly induced by the impulsive action derived
caisson motion. The partial drainage performed between two
wave impact loads is not enough to dissipate the entire excess
pore pressure generated therefore a pore pressure accumulation
process is developed. Just before a tenth impact load takes
place, the accumulated excess pore pressure close to the sand
layer surface is almost
2
0.8
kN m
. Once the impulsive wave
action is finished, no extra excess pore pressure generation is
performed but a pure dissipation process develops. While this
dissipation process is taking place, the extra settlements
observed induced by an elastoplastic consolidation process are
negligible. After
200
s
the pore pressure derived by impulsive
wave action dissipates completely in the vicinity of the sand
layer surface.
5 CONCLUSIONS
A theoretical model for the soil-water-structure interaction that
permits the analysis of non-linear seafloor dynamics induced by
sea wave actions in a vertical breakwater structure is presented.
Proposed model is able to analyze the fundamental aspects
involved in the geomechanics associated with the foundation of
gravity maritime structures: Complex caisson-rubble mound
interaction, soil skeleton-pore fluid coupling and degradation of
the seabed and long term effects mainly due to repetitive
loading, eventually leading to a diffuse failure mechanism.
The principal characteristics of the instantaneous response
experimentally deduced are reproduced adequately. Moreover,
the model proposed is able to reproduce satisfactorily the
accumulative settlement behaviour induced by impulsive sea
wave actions including correlation with pore pressure increase
and effective stress decrease.
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