Environment, Coasts, Oceans, & Infrastructure

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Syed Alvi R.Eng, M.ASCE
Karachi
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I'm not sufficiently knowledgeable to answer your question. Unless someone else can answer, try the ASCE library search at the link below. The Pipelines Conference in 2025 may have papers that will get you started.

ASCE Library: 

Bill Mc

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William McAnally Ph.D., P.E., BC.CE, BC.NE, F.ASCE
ENGINEER
Columbus MS
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Syed – further to Bill's, here are something from some of my early experiences and later my teaching – on ocean outfall diffuser and effluent pipeline designs.

One of the best books I found was: Prof (professor of Ocean Engineering at Texas A&M University) RE Randall's 1997 book, Elements of Ocean Engineering, Society of Naval Architects and Marine Engineers.

Prof Randall laid out seabed pipeline stability analyses and designs in clear terms of static loads, hydrodynamic loads, pipeline stability dynamics lying on seabed and burial requirements.

If not consulted already, have a look. I see now that the book has an updated 2010 version. Here is the link: Elements of Ocean Engineering.

As you can understand – a subsea pipeline traversing multiple hydrodynamic zones from deep water to beach head regions – have different levels of exposure to hydro-wave-dynamic loads including wave breaking and scour – and of course, the reactive forces from the ground.

Pipeline installation or laying from boats require suitably placed ballast to sink the pipeline (such as HDPE) to the seabed – and while laid, the ballasts working at pipeline anchors.

To close – anyway, hope you will find all the tools in the referred book as well in other websource materials for your problems.

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Dr. Dilip K Barua, PhD

Website Links and Profile

In addition to the points raised by Bill and Dilip, it should be noted that any submerged object possessing volume-such as a pipeline-is inherently subject to buoyancy forces. In the absence of adequate ballast or anchor blocks, the pipeline would be prone to uplift and potential flotation. Furthermore, the provision of ballast or anchoring systems contributes to the overall stability of the pipeline, which should be confirmed through detailed engineering analysis.

Kind Regards,

Ahmed Sayed Mohamed, PhD, BC.CE, CEng, F. ASCE, F.RINA

Associate Principal Coastal Engineer

Geotechnical and Heavy Civil Eng. Dep.

Smart Village, Street 26, Building 10

P.O. Box: 129, Giza 12577, Egypt

Tel (direct): +202 35318223

Tel:  +202 35318000 (Ext: 1153)

dar.com

 

Please consider the environment before printing this document

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Ahmed Ahmed Ph.D., C.Eng, BC.CE, F.ASCE
Associate Principal Coastal Engineer
Dar Al Handasah (Shair and Partners)
Giza
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Anchor blocks are not required for a straight, flat, fully butt-fusion welded, buried HDPE DN800 water pipeline. Because butt-fusion joints transfer tensile loads continuously along the pipe, a fully welded HDPE pipeline behaves as a single monolithic structure. When buried at a depth of 3 meters, the friction between the pipe's outer surface and the surrounding soil completely restrains any thermal expansion or contraction. This self-restraint eliminates the need for concrete anchor blocks along the straight run.

Your project parameters naturally mitigate the forces that usually demand anchoring- please refer the below:

• Flat Terrain & No Fittings: Anchor blocks are primarily thrust blocks. Without elbows, tees, valves, or steep slopes, there are no unbalanced hydrodynamic thrust forces to restrain.
• Butt-Fusion Welded Joints: Butt-fusion welding creates joints that are as strong as, or stronger than, the pipe itself. The pipeline possesses full end-restraint capability, meaning it can safely handle internal tensile and compressive stresses without pulling apart. [1]
• Deep Burial Depth (3 meters): Soil overburden pressure at 3 meters creates massive frictional resistance against the pipe wall. The pipe reaches its "anchor point" (the distance from an end or change of direction where soil friction completely locks the pipe in place) very quickly. - Thanks - This may help - please check with any other available references as well

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Madhu Edara P.E., M.ASCE
Engineer
West Palm Beach FL
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What is the purpose of anchor block in HDPE piping?

Ans: When a moving mass of water (or any lump of material in that matter) moves in a certain direction (must be a straight line; as a vector), by virtue of having velocity (a vector) the mass will possess momentum (quantified as  m*v or mass times velocity). To effect a change in direction of the moving mass of water (change is pipe angle or bent), provisions of a force has to be supplied (or added; i.e., the external reaction to the pipe through a thrust block, ideally, where the water "jet/stream" 'hit' the pipe to effect the change in direction, i.e., at the pipe bent;  the reaction may be distributed over a few supports). Momentum is a vector quantity and change in momentum is equal to force (the thrust; water hammering also contributes). This is required to keep the piping system "together" (without breaking/falling apart). Visualize the pipe body as essentially static mass supported by soil, but the "jet" of water moving through it as a dynamic free mass, except small dynamic friction at pipe-water contact surfaces. Thrust/anchor block requirement is not really unique to any pipe material type but may vary with pipe  materials, and stresses due to thrust should be included with other pipe stresses. 

Various British Standards (on hydro-power) or Indian standards tend to have more convenient details or even some example calculations (basically, forces due to change in momentum calculations) perhaps due to considerably less inherent liability concerns than the engineering practices in the United States. A submerged pipeline can be subject to additional external hydrodynamic forces due to ocean wave action, but that is not true for a water line on land or buried underground. 

 

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Monayem Akhand Ph.D., P.E. (Texas), M.ASCE
Civil/Structural Engineer
Portsmouth, VA
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U.K.'s "CIRIA C816: Buried pressure pipelines: designing for thrust restraint"  is a very good and authoritative "standard" for thrust bock requirements and design. You may want to consult it.  

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Monayem Akhand Ph.D., P.E. (Texas), M.ASCE
Civil/Structural Engineer
Portsmouth VA
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