An experimental study to assess the geotechnical performance of dynamically embedded plate anchors

Anthony Patrick Blake

    Research output: ThesisDoctoral Thesis

    313 Downloads (Pure)

    Abstract

    [Truncated] The dynamically embedded plate anchor (DEPLA) has been proposed as a cost effective and technically efficient anchor for deepwater mooring applications. The DEPLA is rocket or torpedo shaped anchor that comprises a removable central shaft and a set of four flukes. The DEPLA penetrates to a target depth in the seabed by the kinetic energy obtained through free-fall in water. After embedment the central shaft is retrieved leaving the anchor flukes vertically embedded in the seabed. The flukes constitute the load bearing element as a plate anchor. The DEPLA combines the installation advantages of dynamically installed anchors (no external energy source or mechanical operation required during installation) and the capacity advantages of vertical loaded anchors (sustain significant horizontal and vertical load components).

    Despite these advantages there are no current geotechnical performance data for the DEPLA, as development of the anchor is in its infancy. This thesis has focused on assessing the geotechnical performance of DEPLAs through an experimental study involving a centrifuge testing program and an extensive field testing campaign. The centrifuge tests provided early stage proof of concept for the DEPLA and motivation for subsequent field testing. The field tests were carried out on reduced scale DEPLAs at two sites: (i) Lough Erne, which is an inland lake located in County Fermanagh, Northern Ireland and (ii) the Firth of Clyde which is located off the West coast of Scotland. The reduced scale anchors were instrumented with a custom-design, low cost inertial measured unit (IMU) for measurement of anchor motion during installation. The field tests were designed to assess the behaviour of the DEPLA during free-fall in water and dynamic embedment in soil, and quantify the loss in embedment during keying and the subsequent plate anchor capacity. Analytical design tools for the prediction of DEPLA embedment and capacity were verified, refined and calibrated using the centrifuge and field data.
    Original languageEnglish
    QualificationDoctor of Philosophy
    Publication statusUnpublished - Nov 2015

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