1999 Fiscal Year Final Research Report Summary
Experimental Study for Effect of Underreamed End Shapes on Bearing Capacity of Enlarged piles
| Project/Area Number |
10650565
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Building structures/materials
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| Research Institution | Hiroshima University |
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Principal Investigator |
YAMAMOTO Haruyuki Hiroshima University, Graduate School for International Development and Cooperation, Associate Professor, 大学院・国際協力研究科, 助教授 (60158293)
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| Project Period (FY) |
1998 – 1999
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| Keywords | enlarged pile / end shares / vertical bearing capacity / model test |
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| Research Abstract |
Model tests were conducted on the enlarged piles with flat and under-reamed ends in sand, to study the characteristics of its bearing capacities. The results are showed as follows.
1) For the tests of mortal model piles, the experimental results revealed that the first cracks on the end surface of the flat form of the enlarged base pile occurs when the applied load was between 50% and 60% of the failure load of the shaft part. In addition, these model tests clarified that the pencil form under-reamed end Pile produces no cracks on its end from ground confining pressures. But the resistance stiffness of the pencil form pile decreased when the convergent angle of its end became sharper. Therefore, the convergent angle of the pencil form should be slight in order to prevent the cracks, and also the large decline in resistance stiffness between the load and settlement.
2) The enlarged piles with flat type ends appear to have a slightly lower supporting load than straight ones with the same diameter, in spite of having the same supporting area due to loosened soil around the enlarged Part during Penetration,
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