Glide block or out-runner block impact on suspended submarine pipeline

Chi, Ken Fai (2012) Glide block or out-runner block impact on suspended submarine pipeline. Masters thesis, Memorial University of Newfoundland.

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Due to the high demand of oil and gas, offshore exploration and development are forced to explore and/or develop near areas of potential slope failure. A glide block or out-runner block is the product of a slope failure and can cause great damage on offshore structures, such as a submarine pipeline, since it can travel a long distance from its origin and carries the soil properties of the parent slide. -- To better understand the drag force generated from a glide block or out-runner block on to a suspended submarine pipeline, 11 physical tests were conducted to quantify it and are presented in this thesis. The tests were conducted in a geotechnical centrifuge located at C-CORE under submerged conditions with a centrifugal force of 30 times the Earth's gravity (i.e., N = 30) and simulated impact situations under steady state conditions and uniform velocities. The soil blocks (approximately 4.5 m high in prototype terms) were made of kaolin clay with undrained shear strengths ranged from 4 to 8 kPa. The model pipes were 6.35 and 9.52 mm in diameter, which corresponds to 0.19 and 0.29 m in prototype. The impact velocities ranged from 0.04 to 1.3 rn/s. The pipe centerline was at mid-height of the block. The shear strain rates, defined as the ratio of impact velocity to pipe diameter, in the centrifuge model are N times higher than that in the prototype, and it ranged from 4 to 137 reciprocal seconds. Hence, the test results are applicable to a wide range of field situations. A geotechnical approach was adapted, based on the results of the centrifuge tests, and a method is presented for estimating drag force for soil block impacting on submarine pipeline.

Item Type: Thesis (Masters)
Item ID: 10299
Additional Information: Includes bibliographical references (leaves 92-95).
Department(s): Engineering and Applied Science, Faculty of
Date: 2012
Date Type: Submission
Library of Congress Subject Heading: Underwater pipelines--Safety measures; Soil-structure interaction; Structural analysis (Engineering); Pipeline failures.

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