History Of Liquefaction Research Articles

首都直下地震による液状化の発生と被害

Liquefaction and damage caused by anticipated near-field earthquakes in the Tokyo metropolitan area are outlined on the basis of official reports released by Central Disaster Management Council of Cabinet Office, Japan, and Tokyo Metropolitan Disaster Management Council. The history of liquefaction during past earthquakes in the area is introduced and correlation between past occurrences of liquefaction and seismic intensity is discussed. Finally, comments are presented on some aspects of liquefaction-induced damage and points of concern during future earthquakes.

Special Issue on Liquefaction around Marine Structures: Miscellaneous

The European Union EU supported a 3-year 2001–2004 research program on Liquefaction around Marine Structures LIMAShttp://vb.mek.dtu.dk/research/limas/limas.html. This writer was coordinator of this program. A consortium of 10 European institutions universities, hydraulics and geotechnicalengineering laboratories, and consulting companies undertook this program. The objectives of the program were two-fold: 1 to investigate potential risks for failure of structures due to liquefaction; and 2 to prepare and disseminate practical guidelines guidance for design and maintenance that were developed from present research and also taking into consideration all state-ofthe-art knowledge. The present volume and a previous one JWPCOE 2006 are a collection of fifteen papers and a technical note produced from the research undertaken in the LIMAS program. The papers in the previous volume Vol. 132, No. 4 summarized results of experimental and theoretical investigations on the fundamental aspects of soil liquefaction around marine structures and focused on processes and benchmark cases including physics of liquefaction phenomena around marine structures, stability of submarine pipelines on liquefied seabeds, critical flotation density of pipelines in soils liquefied by waves, liquefaction around pipelines under waves, numerical modelling of wave-induced liquefaction around pipelines, fluid-soil-structure interaction in liquefaction around a cyclically moving cylinder; guidelines for pipeline on-bottom stability on liquefied noncohesive seabeds, large-scale experiments on pore pressure generation underneath a caisson breakwater, and liquefaction phenomena underneath marine gravity structures subjected to wave loads. The present volume includes papers on various other aspects of soil liquefaction and focuses on applications, including field investigation of momentary liquefaction and scour, momentary liquefaction and gas content; scour around piles in the case of 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, governmental authorities, and research entities at universities/research institutions within the coastal and offshore engineering and geotechnical and foundation engineering communities.

Special Issue on Liquefaction around Marine Structures

In geotechnical-engineering terminology, liquefaction refers to the state of the soil in which the effective stresses between individual 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 Fredsoe 2002 , 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 EU supported a three-year 2001–2004 research program on LIquefaction around Marine Structures LIMAS 2004 http://vb.mek.dtu.dk/research/limas/limas.html . The guest editor, B. Mutlu Sumer, was coordinator of this program. A consortium of 10 European institutions universities, hydraulics and geotechnical-engineering laboratories, and consulting companies undertook this program. The objectives of the program have been twofold: 1 to investigate potential risks for failure of structures caused by liquefaction; and 2 to prepare and disseminate practical guidelines guidance for design and maintenance , to be developed from the present research and also considering 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 investigations 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 issue 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, governmental 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 sequence of sediment behaviour during wave‐induced liquefaction

AbstractThis paper presents the results of an experimental investigation of the complete sequence of sediment behaviour beneath progressive waves. The sediment was silty with d50 = 0.060 mm. Two kinds of measurements were carried out: pore‐water pressure measurements (across the sediment depth), and water‐surface elevation measurements. The process of liquefaction/compaction was videotaped from the side simultaneously with the pressure and water‐surface elevation measurements. The video records were then analysed to measure: (i) the time development of the mudline, (ii) the time development of liquefaction and compaction fronts in the sediment and (iii) the characteristics of the orbital motion of the liquefied sediment including the motion of the interface between the water body and the sediment. The ranges of the various quantities in the tests were: wave height, H = 9–17 cm, wave period, T = 1.6 sec, water depth = 42 cm, and the Shields parameter = 0.34–0.59. The experiments reveal that, with the introduction of waves, excess pore pressure builds up, which is followed by liquefaction during which internal waves are experienced at the interface of the water body and the liquefied sediment, the sequence of processes known from a previous investigation. This sequence of processes is followed by dissipation of the accumulated excess pore pressure and compaction of the sediment which is followed by the formation of bed ripples. The present results regarding the dissipation and compaction appear to be in agreement with recent centrifuge wave‐tank experiments. As for the final stage of the sequence of processes (formation of ripples), the ripple steepness (normalized with the angle of repose) for sediment with liquefaction history is found to be the same as that in sediment with no liquefaction history.

Liquefaction Testing of Stratified Silty Sands

The cyclic behavior of stratified silty sandy soils is at present poorly understood, yet these materials are commonly found in alluvial deposits and hydraulic fill, which have a history of liquefaction during earthquakes. The main objective of this research project was to compare the behavior of stratified and homogeneous silty sands during seismic liquefaction conditions for various silt contents and confining pressures. A comprehensive experimental program was undertaken in which a total of 150 stress-controlled undrained cyclic triaxial tests were performed. Two methods of sample preparation were used for each soil type. These methods included moist tamping (representing uniform soil conditions) and sedimentation (representing layered soil conditions). The silt contents ranged from 10 to 50%, and confining pressures in the range of 50 to 250 KPa were considered. The results indicated that the liquefaction resistances of layered and uniform soils are not significantly different, despite the fact that th...

Synthetic Fuel Technology Development in the United States: A Retrospective Assessment

The Context of Direct Coal Liquefaction Development in the Synthetic Fuels Technology Arena Retrospective Technology Assessment: Methods and Approach Analytical Framework for Retrospective Technology Assessment of Direct Coal Liquefaction Pre-1939 Development of Direct Coal Liquefaction History of Direct Coal Liquefaction Development in the United States H-Coal: The Baseline Case An Economics-Driven Perspective on Direct Coal Liquefaction A Public Policy-Driven Perspective on Direct Coal Liquefaction Conclusions--The Effects of Support Hiatus on Direct Coal Liquefaction Development