Special Issue on Liquefaction around Marine Structures: Miscellaneous

Abstract

In geotechnical-engineering terminology, liquefaction refers to the state of the soil in which the effective stresses between indi-vidual soil grains vanish and the water-sediment mixture as a whole therefore acts like a fluid. Under this condition, the soil fails, therefore precipitating failure of the supported structure such as pipelines, breakwaters, seawalls, pile structures, sea barriers, and revetment systems. Although a substantial amount of knowledge has accumulated on flow and scour processes around marine structures in the last decade or so ͑Whitehouse 1998; U.S. Army Corps of Engineers 2001; Sumer and Fredsøe 2002͒, comparatively little is known about the impact of liquefaction on these structures. The topic has received little coverage in recent research, which has substantially advanced the design of coastal structures but not the design of their foundations with regard to soil liquefaction. The European Union ͑EU͒ supported a three-year ͑2001–2004͒ research program on LIquefaction around Marine Structures ͑LIMAS 2004͒ ͑http://vb.mek.dtu.dk/research/limas/limas.html͒. The guest editor, B. Mutlu Sumer, was coordinator of this program. A consortium of 10 European institutions ͑universities, hydraulics and geotechnical-engineering laboratories, and con-sulting companies͒ undertook this program. The objectives of the program have been twofold: ͑1͒ to investigate potential risks for failure of structures caused by liquefaction; and ͑2͒ to prepare and disseminate practical guidelines ͑guidance for design and mainte-nance͒, to be developed from the present research and also con-sidering all state-of-the-art knowledge. The present volume and a follow-up one are a collection of fifteen papers and a technical note produced from the research undertaken in the LIMAS program. The papers in this volume summarize the results of experimental and theoretical investiga-tions on the fundamental aspects of soil liquefaction around marine structures and focus on processes and benchmark cases. The follow-up volume ͑scheduled for the November issue͒ will include papers on various other aspects of soil liquefaction, including field investigation of momentary liquefaction and scour, momentary liquefaction and gas content, scour around piles in soil with liquefaction history, soil reaction in saturated sand under impulsive loads, development of a sampler for measurement of gas content in soils, and seismic-induced liquefaction around marine structures. The publication of this group of papers will disseminate the results of the LIMAS program worldwide, appealing to end users in consulting companies, contractors, gov-ernmental authorities and research entities at universities and research institutions within the coastal and offshore engineering and geotechnical and foundation engineering communities. The publication of this special issue is believed to have broad appeal worldwide and will also build content and create interest in this currently popular area. The idea of publishing this special issue was first proposed in 2003, almost halfway through the LIMAS program. The guest editor contacted Dr. Zeki Demirbilek, the editor of the journal until November 2005, to determine the possibility of publishing a special issue in JWPCOE, that would discuss the subject by using papers essentially produced under the LIMAS program. The re-sponse from Dr. Demirbilek was positive. He added in his re-sponse that " The idea of developing special issues for JWPCOE was considered to be a splendid one, and I have obtained ASCE's endorsement and support for it. ASCE will be encouraging editors to plan special issues as a way of building content and creating interest in particular disciplines that are either currently 'hot' or potentially growth areas for their journal. " On this premise, the guest editor started to organize what has become a three-year project, a project that included several components, ranging from collecting the papers to finding peer reviewers, collecting the re-view reports, completing reviews by carefully evaluating papers and the peer-review reports, making final decisions, and so on. During this process, the guest editor has had an enormous amount of support from many colleagues.