Page 141 - Pipelines and Risers

114 Chapter 8

found through series of pipeline response simulations to be the weight where the pipe is
“dynamically” stable (due to penetration) for the given external load level.

2) The second design check makes an absolute static stability calculation of a pipeline
trenched and or buried in the soil, sand or clay. The design check is based on static
equilibrium between the hydrodynamic design loads and the soil capacity.

8.5 Use of FE Analysis for Intervention Design.

8.5.1 Design Procedure

Preparation
- Load sequences
- Pipe parameters
~ Seabedkoil parameters
- Import seabed model from DTM
- Environmental parameterr

Decide
Seabed interventiou ?

Not OK Run Analysis
Evaluate Results
~ Displacements
-Stress and strain
- Bending moments

Postprocessing
Postprocessing using adequate
spreadsheet for presenting results and
storage.

Figure 8.1 Flow-chart for seabed intervention design procedure.

8.5.2 Seabed Intervention
There are several types of seabed intervention. Examples of seabed intervention are rock
dumping, trenching, burying and pre-sweeping. The purpose of seabed intervention design is
to ensure that the pipeline maintains structural integrity throughout its design life. It is then a
premise that a good work has been done when the design criteria is established and compared
with the simulated pipeline response to a history of loads.