| Budget Amount *help |
¥4,500,000 (Direct Cost: ¥4,500,000)
Fiscal Year 1999: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1998: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1997: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Research Abstract |
Heavy tamping is one of ground improvement technique for loose sandy and gravelly ground and rock waste fill. This method generally aims at uniformly compacting the whole ground, however, we found that a high density compacted area bulbously grew up beneath the tamping point by ram blow. The purpose of this study is to investigate the adaptability and practical application of 'Compacted Bulb Foundation Method', which applies heavy tamping to the spread foundation. Firstly a series of centrifuge model tests was carried out to investigate effects of kind of soils on bearing capacity of compacted bulb foundation. Secondly a series of centrifuge model tests was carried out to investigate effects of tamp condition ( ram mass, ram base area, drop height and number of blows) and foundation bed area on the bearing capacity characteristics in miniaturizing this method in order to use practically.
Main conclusions are as follows : 1) within the material which changed maximum grain size and fine content which used this study, there is seldom the effect of kind of soils on this method, 2) it is possible to obtain sufficiently large bearing capacity, even if the tamp condition is miniaturized, 3) the bearing capacity of the compacted bulb is more dependent on total momentum than total tamping energy, 4) coefficient of subgrade reaction is larger, as ram base area is larger. From these results, the following are proposed : design method in using compacted bulb foundation method practically, necessary condition of the construction machine and construction management technique.
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