1887

oa Civil Engineer in South Africa - Wave forces on submarine pipelines

Volume 22, Issue 12
  • ISSN : 0009-7845

 

Abstract

Theory presently available for estimating wave forces on submarine pipelines is reviewed. Areas in which some agreement has been reached are pointed out as well as aspects that need special attention before wave forces can be predicted with confidence.


A new approach formulating a system of hydrodynamic forces on a cylinder is suggested. This approach may lead to the adoption of a more rational set of significant forces acting on a submarine pipeline.
Recommended procedures from two of the most relevant publications available to date are applied to calculate resultant hydrodynamic forces on the proposed Green Point outfall sewer, Cape Town. Some contradictions are apparent and reasons for these are discussed.
The main conclusions are that hydrodynamic force coefficients should be analysed in terms of three parameters - the Reynolds number, the period parameter and the relative clearance, that the transverse force needs further investigation and that the lift force should perhaps be subdivided into a so-called vortex lift force and a Bernoulli lift force.

Huidig-beskikbare teorie vir die beraming van golfkragte op ondersese pyplyne word in oënskou geneem. Gebiede waarin eenstemmigheid bereik is, word aangetoon asook aspekte wat verdere aandag verg alvorens golfkragte metvertroue voorspel kan word.


'n Nuwe benadering tot die afleiding van hidrodinamiese kragte op 'n silinder word voorgestel. Hierdie benadering mag moontlik lei tot die aanvaarding van 'n meer rasionele sisteem van betekenisvolle kragte wat op 'n ondersese pyplyn inwerk.
Die aanbevole prosedures van twee van die mees toepaslike verhandelinge tot dusver beskikbaar word aangewend om die resultante hidrodinamiese kragte op die voorgestelde Groenpuntse riool-uitloop by Kaapstad te bereken. Sekere teenstrydighede word aangetref en redes hiervoor word bespreek.
Die hoofgevolgtrekkinge is dat hidrodinamiese krag-koëffisiënte in terme van drie parameters ontleed moet word - die Reynoldsgetal, die periode-parameter en die relatiewe hoogte, dat die transversale krag verder ondersoek moet word en dat die opligkrag miskien in 'n sogenaamde werwelopligkrag en 'n Bernoulli-opligkrag onderverdeel moet word.

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/content/civeng1/22/12/EJC24792
1980-12-01
2016-12-11

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