deployment of an otec pipeline
283
respectively. In Figure 10.14b, where L = 549 m, the profile for the lighter
ballast is not shown since those responses are unbounded, as shown in Table
10.3. The heavier ballast did stabilize the System, however, where tc = 580 s. In
these studies, an unbounded response was defined whenever the ratio v(L, tc)/L
exceeded unity.
Shown in Table 10.4 are the effects of K, the rotational stiffness restraint at
the barge end, on the dynamic pipe response and stability. These results show
that, for a ballast mass of Mo - 45400 kg, an increase in A" by a factor of 100
increased the range of pipe length for which the System remained dynamically
stable. For instance, the System was stable at L = 183 m for the higher rotational restraint but not for the lower rotational restraint. Also, the higher K
reduced the peak deflection in the range up to L — 183 m, but beyond this
length the stable deflections often exceeded those corresponding to the lower K
value.
Table 10.4 Effects of Torsional Restraint on Peak Pipe Responses for a Ballast
of Mo = 45 000 kg and a Simulation Time of 600 s
Pipeline
Length L,
m
Torsion Constant,
Torsion Constant,
1.13 x 1010 N m/rad
1.13 x 108
Deflection
v(L,tc),
m
N-m/rad
Moment
Mc(z,t),
105 N-m
Deflection
v(L,tc),
m
Moment
Mc(i,t),
105 N m
61
9.63
-51800
7.44
-53490
122
24.4
13000
-6.01
14100
183
*
*
6.14
6290
244
6.27
3390
-11.40
4400
305
-6.28
-2 290
17.79
3180
366
9.85
-1730
-26.89
-2470
427
-5.00
-1420
-10.80
-1960
488
13.2
2 730
*
*
549
*
*
-13.12
-3140
610
*
*
-8.28
1700
671
216
40200
-20.86
5530
732
*
*
-71.29
15800
793
-108
40300
-329
-94880
854
-139
89100
4.54
-2910
915
*
*
*
*
976
*
*
-249 -118800
1037
*
*
•
—
It is concluded that this analysis can be used to détermine the feasibihty<*
deploying any vertical cold-water pipe from a typical barge in a given sea s .
These exploratory studies showed that deployment is a délicate tas sine
may exist a range of pipe lengths longer than 500 m, for instance, w
bounded deflections and moments occur. Such pipe instabilities mav
283
respectively. In Figure 10.14b, where L = 549 m, the profile for the lighter
ballast is not shown since those responses are unbounded, as shown in Table
10.3. The heavier ballast did stabilize the System, however, where tc = 580 s. In
these studies, an unbounded response was defined whenever the ratio v(L, tc)/L
exceeded unity.
Shown in Table 10.4 are the effects of K, the rotational stiffness restraint at
the barge end, on the dynamic pipe response and stability. These results show
that, for a ballast mass of Mo - 45400 kg, an increase in A" by a factor of 100
increased the range of pipe length for which the System remained dynamically
stable. For instance, the System was stable at L = 183 m for the higher rotational restraint but not for the lower rotational restraint. Also, the higher K
reduced the peak deflection in the range up to L — 183 m, but beyond this
length the stable deflections often exceeded those corresponding to the lower K
value.
Table 10.4 Effects of Torsional Restraint on Peak Pipe Responses for a Ballast
of Mo = 45 000 kg and a Simulation Time of 600 s
Pipeline
Length L,
m
Torsion Constant,
Torsion Constant,
1.13 x 1010 N m/rad
1.13 x 108
Deflection
v(L,tc),
m
N-m/rad
Moment
Mc(z,t),
105 N-m
Deflection
v(L,tc),
m
Moment
Mc(i,t),
105 N m
61
9.63
-51800
7.44
-53490
122
24.4
13000
-6.01
14100
183
*
*
6.14
6290
244
6.27
3390
-11.40
4400
305
-6.28
-2 290
17.79
3180
366
9.85
-1730
-26.89
-2470
427
-5.00
-1420
-10.80
-1960
488
13.2
2 730
*
*
549
*
*
-13.12
-3140
610
*
*
-8.28
1700
671
216
40200
-20.86
5530
732
*
*
-71.29
15800
793
-108
40300
-329
-94880
854
-139
89100
4.54
-2910
915
*
*
*
*
976
*
*
-249 -118800
1037
*
*
•
—
It is concluded that this analysis can be used to détermine the feasibihty<*
deploying any vertical cold-water pipe from a typical barge in a given sea s .
These exploratory studies showed that deployment is a délicate tas sine
may exist a range of pipe lengths longer than 500 m, for instance, w
bounded deflections and moments occur. Such pipe instabilities mav