| Recent major seismic events such as the Loma Prieta 1989 and the 1995 Hyogoken-Nanbu earthquakes continue to demonstrate the damaging effects of liquefaction-induced loss of soil strength and associated lateral spreading. Currently, major challenges are encountered in the development and evaluation of cost-effective remedial measures. Accordingly, the main aim of this research is to improve the understanding of ways to develop and implement cost-effective remedial measures in order to resist earthquake induced liquefaction. This objective was achieved in two ways.; First, a thorough literature survey was done, and the current state of knowledge concerning soil improvement against liquefaction was summarized. Definition, current practice, and historical use of all viable liquefaction countermeasure techniques are presented. Analytical and experimental work performed on these techniques are discussed. A major effort is expended in reviewing as many publications as possible. Consequently, the compiled literature survey may be considered one of the most comprehensive on this subject.; Second, liquefaction hazard mitigation effects of different soil improvement techniques are evaluated mainly by means of centrifuge modeling experiments. Throughout this study, 90 shaking tests were performed on 34 different soil models. The tested improvement techniques included: preloading-overconsolidation, suction-vacuum application, densification, geogrid-geofiber inclusions, cementation, surcharge application, and sheet-pile enclosure. The test results are compared and related as much as possible to field experience and engineering applications. The presented results constitute a valuable contribution towards the development of rational models and design concepts for remediation of liquefiable soils. |
