الفهرس 
Title : Effectiveness of Concrete Rigid Inclusions for Reclaimed Liquefiable Soils Surrounding Coastal Structures
SummaryOnly 14 pages are availabe for public view
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Abstract
Coastal reclamation is increasingly being used to create land for development, but the main challenge in constructing new coastal reclaimed regions is the geotechnical problem represented in the problematic marine and hydraulic fill soil conditions. Rigid inclusions system, or soil reinforcement by columns, have grown more popular as a soil improvement technique for reclaimed coastal areas in recent decades. It solves a wide range of foundation problems in which cost and timing are critical considerations. The main advantages of this system are enhancing the bearing capacity, decreasing the settlement, and insuring the slope stability. However, many of the coastal reclaimed projects can be existed in regions with significant seismic activity and this may lead to the liquefaction risk causing liquefaction-induced deformations and failures. Mitigation of liquefaction-induced deformations and hazards can be a bi-product of rigid inclusions technique. The efficiency of concrete rigid inclusions system in mitigating liquefaction-induced deformations for reclaimed soils surrounding coastal structures has received little attention in the literature. This research study adopts a numerical approach to examine the efficiency of the concrete inclusions system in reducing the deformations caused by liquefaction in the reclaimed liquefiable soil deposits that surround the coastal structures, as well as to emphasize certain design criteria for this mitigation technique.
Modeling methodology using products of the 2D finite element software GeoStudio 2012 were developed and employed to simulate and analyze the well-known and well-documented case history of gravity type caisson quay wall in Rokko Island, in Japan, from 1995 Kobe earthquake. Thereafter, the developed numerical model was validated by comparing the resulting deformations for the simulated case history with the field observation records and the findings from previous studies in literature for the same case history. Utilizing the validated modelling methodology and the simulated case history as an unimproved framework, a parametric study was performed to examine the performance of the case history site where the replaced soil underneath the caisson quay wall and the retained reclaimed backfill soil were improved by means of concrete rigid inclusions. Within the parametric study, series of numerical analysis were accomplished to study the effect of different design variables on the predicted deformations, in particular the effect of the inclusions area replacement ratios, extension depths of the inclusions, and the earthquake shaking characteristics. Analysis and evaluation of the results have been focused on the resulting deformations of the caisson quay wall besides to the horizontal and vertical displacements of foundation and backfill soils, and the surficial settlement of the retained backfill.
The numerical analysis outcomes indicated that concrete rigid inclusions system can be active in mitigating the resulting deformations due to liquefaction in the liquefiable reclaimed coastal soil deposits, particularly for moderate earthquake shakings. Furthermore, it improves the performance of the constructions and structures that are susceptible to this system. The study provided an insight into the key design parameters that can be applied to the concrete rigid inclusions system to assure its effectiveness in reducing the liquefaction-induced deformations.