Shore approach trenching/backfilling

[pipeline058]

It seems DnV do not have any recommended practice for calculation of shore approach trench depth and the thickness and type of backfill.
I found a common value of 1m for covering the pipeline (1m backfilling over top of pipeline).
Does anyone have a good reference for:
What shall be checked? (liquidification of soil, etc.?)
and what is the criteria?

 

[BigInch]

1 meter isn't enough unless its a lake small enough that you'd never get waves or wind induced currents. A typical value might be more like 10 to even 15 feet if in an exposed sandy beach. In rock it may be less. It depends on how susceptible the beach is to erosion to begin with considering mostly type of exposture to open water, magnitude of storms and the underlying beach material. Potential washouts can be estimated by projected current speed, liquifaction potential due to passing wave pressures, orbital velocity at the mud line of shoaling waves and weight of beach material particles. Often the material above is replaced with heavier rock or concrete mattresses as well. At times, the beach approaches may be horizontally drilled, if there is a cliff or similar obstruction.

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"The problem isn't finding the solution, its trying to get to the real question." BigInch

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