| Summary: | 碩士 === 國立屏東科技大學 === 土木工程系所 === 95 === This research is to focus on the columns formed by pressure jetted pile as a countermeasure for the soil improvement on the special purpose of the underneath structure. The strata of the study site are formed by sand and clay layers. The factor of safety about liquefaction resistance for sand layers up to 20 meters deep was found less than 1 while a peak horizontal ground surface acceleration is assumed to be 0.495 g.
As being shown by the research result, the higher liquefaction potential can be found in some sand layers during the major earthquake; special consideration must be taken, such as the pile foundation or the soil improvement.
After several contingencies have been considered, it is concluded that the high-pressure jet grouting columns can be useful. The nominal diameter of columns is 1 meter whereas depth ranges from GL.-5.72~15.0 m; improvement ratio (Ir,) is approximately 8.7%. The columns have been approved effective restrain liquefaction, cyclic shear strain and excess pore pressure expansion, and also ground settlement while an earthquake happens. It also can increase the average soil strength and decrease the soil deformation. The safe factor of soil improvement is examined after strata have been achieved.
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