• Journal of the Korean Geotechnical Society
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• v.16 no.4
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• pp.31-42
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• 2000

In this study, the stability of group piles installed in deep sea to the seaquake was studied by performing the calibration chamber model tests for open-ended pipe piles, grouted piles under soil plug and close-ended piles installed in the simulated deep sea. For each case (a single pile, 2-pile and 4-pile groups), series of seaquake tests were performed. While, during the simulated seaquake, the compressive capacity of the single open-ended pile depended on pile penetration depth(=7m), were found to be stable. But, a single grouted pile with penetration depth of 13m kept "mobility" state, the one with penetration depth of 20m was stable and grouted pile groups with penetration depth of 7m were stable regardless of pile penetration depth. By grouting soil plug of open-ended piles and soil under the pile toe of open-ended pipe piles installed in the deep sea, failure of soil plugging was prevented. Thus, close-ended piles were more stable than open-ended pile against the seaquake motionake motion.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.3
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• pp.45-54
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• 1999

It is known from the previous study on the behavior of sharter single pile during simulated seaquake induced by the vertical component of earthquake that the compressive capacity and the soil plugging resistance of single open-ended pipe pile were completely degraded. But, the capacity of single open-ended pipe pile with greater penetration and the capacity of piles group with shorter penetration were expected to be stable after seaquake motion. In this study, first single pile, 2-pile or 4-pile groups with several simulated penetrations were driven into the calibration chamber with saturated fine medium sand and the compressive load test for each installed pile or pile groups was performed. Then, about 95% compressive load of the ultimate capacity was applied on the pile head during the simulated seaquake motion. Finally, to confirm the reduction of pile capacity during the simulated seaquake motion, the compressive load test for each single pile or pile groups after seaquake motion was performed. During the simulated seaquake, compressive capacities of single open-ended pipe pile and piles group installed in shallow sea were not decreased. But, the stability of open-ended pile installed in deep sea was depended on the pile penetration depth. So, single open-ended pile with greater penetration of 27 m was stable, and 2-pile and 4-pile groups with penetration more than 13m were stable. But, 2-pile groups with penetration of 7m was failed, and the compressive capacity of 4-pile groups with penetration of 7m was degraded about 15%.

• Journal of the Korean Geotechnical Society
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• v.15 no.2
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• pp.165-180
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• 1999

Static load tests were performed for open-ended piles, closed-ended piles, piles with grouted toe, and base-grouted piles by using calibration chamber. Then vertical bearing capacities determined from load tests were compared with each other. The stability of base-grouted pile during a simulated seaquake was investigated by changing the penetration depth. Also, static load tests and seaquake tests for 2-piles and 4-piles group were performed. The bearing capacity of the pile grouted inside the toe was 11.2~30.8% less than that of open-ended pile because of reduction of base resistance due to disturbance of base soil under pile toe. The bearing capacity of a base-grouted pile was 23.8~33.9% more than that of an open-ended pile and was similar to that of a closed-ended pile. The bearing capacity of base-grouted group pile was increased ; the bearing capacity of base-grouted 2-piles group increased 14.6~31.8% compared to that of open-ended 2-piles group, and that of base-grouted 4-piles group increased 15.3~22.4% compared to that of open-ended 4-piles group. During the simulated seaquake in deep sea, stability of base-grouted pile was found to be dependent on the pile penetration depth. During seaquake motion, single long base-grouted pile longer than 20m was stable and short base-grouted pile shorter than 12m failed. But relatively long base-grouted pile longer than 12m kept mobility state. Bearing capacity of base-grouted group pile with penetration depth less than 7m was degraded a little bit ; so, base-grouted group pile could maintain mobility condition.