Masaru KANEKO
Study on effect of liquefaction countermeasure in residential land by compaction gravel pile
Satoru OHTSUKA
Currently, liquefaction countermeasure in the residential land is not progressed much from the effects of the cost and environmental issues. Usefulness of compaction gravel pile method for residential land exerting a combined liquefaction deterrent effect of increased density surrounding soil and drainage is expected. Combined liquefaction deterrent by effect of increased density of surrounding soil and drainage by the compaction gravel pile method has been verified from the field experiment and anamnestic research. However a boundary of the effects of each effect (increased density of surrounding soil, drainage) is not clear. I used a numerical analysis and model to research effect of increased density of surrounding soil and effect of drainage of gravel pile for liquefaction countermeasure by compaction gravel pile. The material constants used in the numerical analysis were determined by fitting the results of analysis simulation to results of tri-axial compression tests. Applied them in the model soil constructed compaction gravel pile, carried out dynamic analysis and compared the improving effect of excess pore water pressure ratio and settlement by changing the condition analysis (the input seismic motion, substitution rate, presence of increased density, etc.,).As a result, it has been clarified that effect of deterrent excess pore water pressure ratio and settlement are depend on increased density by input seismic motion becomes larger. Effect of increased density from the results of the two-dimensional analysis was found to have a significant effect on liquefaction deterrent effect. However, effect of the increased density in two ?dimensional compaction model it was thought that it was overestimate than. So, I carried out reproduction analysis of increased density of the surrounding soil by using three-dimensional compaction model. Compared the N value increments calculated from the analysis results and converted N values increments from field test to verify the validity. As a result, the N value increments calculated from the analysis results fitted to converted N values increments from field test
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