The Hughes Glomar Explorer and a 5,000-m-Long Heavy-Lift Pipe: Coupled Ship and Pipe Motions Measured in North Pacific Ocean

摘要

A 5,000-m-long, 15-in (38-cm) outer-diameter, full-scale pipe wasrndeployed from the large Moon Pool of the Hughes Glomar Explorerrn(Fig. 1) while a deep-ocean mining system operated from the ship inrnthe North Pacific Ocean in 1976 and 1979. From the standpoint ofrndesign as well as operation, one of the most critical parameters in deepoceanrnmining and deep-ocean drilling is the behavior of the pipe alongrnits length, with its bottom free. The at-sea test includes the first-everrnmeasurements of the full-scale pipe responses coupled with thernExplorer's motion in the deep ocean. The measurements showed thatrnthe pipe bottom undergoes dynamic stretching at axial resonance inrnaddition to its static stretch. In addition, this occurrence of axialrnresonance was predicted by the calculations and it agreed with them.rnThe axial resonance period is in the range of the commonlyrnencountered ocean-wave periods. Further, this study in 1976-80rnchanged the industry's common perception of bending stress as designrnstress: The axial stress can be an order of magnitude larger than thernbending stress for such a long pipe, and the bending is less of an issue.rnThis paper presents the axial stress amplitudes, including amplificationrnat the pipe's resonance, which are coupled with the Explorer's motions.rnThis design and operation issue applies to deep-ocean drilling as well.