2016 Fiscal Year Annual Research Report
Experimental and theoretical diagnosis of arch collapse with liquefaction in embankment constructed on soft ground subjected to seismic loading
| Project/Area Number |
15H04037
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| Research Institution | Kyoto University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
木村 亮 京都大学, 工学研究科, 教授 (30177927)
澤村 康生 京都大学, 工学研究科, 助教 (20738223)
竹村 次朗 東京工業大学, 環境・社会理工学院, 准教授 (40179669)
竹山 智英 神戸大学, 工学研究科, 准教授 (00452011)
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| Project Period (FY) |
2015-04-01 – 2018-03-31
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| Keywords | アーチ効果 / 模型実験 / 液状化 / 盛土 / 主応力軸 |
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| Outline of Annual Research Achievements |
Load transfer mechanism of embankment resting on a deformable ground under 50g centrifugal accelerations has been investigated. The amount of basal subsidence was recorded by laser sensors, the static earth pressures were measured by a set of pressure gauges. In centrifuge test, the embankment was made of Edosaki sand and the deformable ground was modeled by Urethane. The embanking process was divided into many layers with thickness 1-1.5 cm, each of which was tamped by a wood stick and finally cut into the trapezoidal shape at the final layer. The onset of arch action is observed by an abrupt stress drop in the vicinity of the center of embankment. To elaborate the arch action, the stress distribution of embankment resting on the deformable ground represented by Urethane was compared with that lying above a rigid base without basal subsidence. The experimental results showed the central pressure drop in embankment in associated to basal subsidence would be induced by arch action forming in the embankment. Moreover, the responses of pressure gauge were examined via multiple loops of centrifugal loading and unloading processes to evaluate the cell action factor. In conclusion, the experiments have highlighted the effect of basal subsidence on the stress redistribution in the embankment.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The preliminary study conducted in 2015 has provided some suggestions for interpreting the results of the current test and improvement in the subsequent study. Based on the results of preliminary tests, the soil chamber with water supply/drainage system has been designed and created. Skills in experimental procedures, material handling and experimental operation have been accumulated. Materials for the embankments and ground have been tested and chosen. The soil chamber has been tested in a vacuum chamber and centrifugal acceleration under 50g to assure the functions of supply/drainage system using water and Metalose. Trial-and-errors on mold of frozen embankment, frozen time, thawing times and pattern of earthquake waves to induced liquefaction and failure have been determined.
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| Strategy for Future Research Activity |
More frequent periods of using centrifuge are increased. All necessary sensors and materials are acquired. Techniques on image analyses are considered and applied to the experiments. Conditions of ground layer in combination of vertical drains and artificial ground using Urethane are studied to obtain the optimum layout. Elementary tests of materials in various degree of saturation will be carried out to obtain the necessary parameters for numerical analyses. Experimentally realizable theories will be developed and validated with the experiments. Numerical simulations of experiments will be conducted and compared with the tests.
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