This paper presents a desktop study on the rockfill strength properties related to the subsea rockfill, which is generally installed at a loose state and under low stress level compared with its onshore counterparts. The rockfill properties are derived based on extensive review of literature available in the public domain, together with our experience in geotechnical testing, design and installation of rockfills. The focus of the present study is on the effective peak internal friction angle, /spl phi/'/sub p/, of the rockfill, placed by the Fall Pipe installation method, by considering its dependency on the stress level. Advice on other parameters, such as friction angle at critical state, /spl phi/'/sub cs/, maximum dilation angle, /spl psi//sub max/, and rockfill submerged weight are also provided. As consistently shown by the various datasets, /spl phi/'/sub p/ and /spl psi//sub max/ are dependent on the stress level, while /spl phi/'/sub cs/ is relatively constant for a given rock type. The simplified stress-dilatancy relationship is found also to be applicable to the sands, with minor adjustment due to the difference between rockfills and sands. A case study is presented at the end to demonstrate how the derived relationships can be applied for real designs.
Hongjie Zhou, Andrew D. Deeks, Amir M. Kaynia, Alasdair Maconochie and Wouter Op den Velde
Keywords: rockfill, strength, friction angle, stress dependency
Publisher: DFI