Document Type

Report

Department/Program

Virginia Institute of Marine Science

Publication Date

5-21-2018

Abstract

A compilation of 761 observations of scour-induced burial and 406 observations of initiation of motion of UXO-like objects are presented. The main factors that increase the scour-induced burial-to-diameter ratio (B/D) under (i) currents and (ii) waves are the (i) Shields parameter (S) and (ii) Keulegan-Carpenter number. For cylinders under waves, B/D additionally increases as the current component parallel to wave orbitals decreases, as S increases, and as the angle between wave orbitals and a cylinder’s axis increases. Cylinders bury most, then spheres, and conical frustums bury least. Simple models dependent on these variables explain 85% of observed variance in B/D. Onset of motion is parameterized by fi S_Ucrit, where S_Ucrit is the critical object mobility parameter, and fi accounts for inertia forces from time-varying pressure gradients. S_Ucrit is observed to decrease systematically as D/k increases, where k is the bed roughness. Theory combined with observations lead to fi S_Ucrit = a1(D/k)^b1. Observations give a1 = 1.75 and b1 = - 0.72, which explains 89% of the observed variance in fi S_Ucrit.

Description

Final report to the Strategic Environmental Research and Development Program (SERDP) associated with SERDP Project MR-2224

DOI

https://doi.org/10.25773/gk95-bb88

Keywords

underwater munitions, unexploded ordnance, scour-induced burial, initiation of motion

MR-2224_Data.xlsx (98 kB)
Data contained in Tables A1, B1, B2 and B3

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