2007 Fiscal Year Final Research Report Summary
Research of the Lightweight Thrust Restraint Methods for Buried Bend using Geosynthetics
| Project/Area Number |
17380143
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Irrigation, drainage and rural engineering/Rural planning
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| Research Institution | Kobe University |
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Principal Investigator |
KAWABATA Toshinori Kobe University, Graduate School of Agricultural Science, Associate Professor (20335425)
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| Co-Investigator(Kenkyū-buntansha) |
MOHRI Yoshiyuki National institute for Rural Engineering, Research Manager (90373224)
UCHIDA Kazunori Kobe University, Gradate School of Agricultural Science, Professor (80111946)
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| Project Period (FY) |
2005 – 2007
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| Keywords | Geoteehnical Engineering / Earthquake resistant / Pipeline / underground structure / Agricultural Engineering / disaster prevention |
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| Research Abstract |
At a bend part of pipeline under the internal pressure, the thrust force occurs with the proportion to the magnitudes of the angle of the bend and internal pressure. Generally, this thrust force is supported by the passive soil pressure which affects background of bend. However damages, separation of joints, have been occurred due to its weight during large earthquake.
In this research, first, new thrust protecting methods using vertically installed geogrid were proposed. And lateral loading tests were carried out in the dry sand ground for model pipes having a 90mm diameter in order to clarify the effectiveness of these new thrust protecting methods using the geogrid. As the results, it was found that these new methods were very effective as a thrust protecting method for lateral forces due to internal pressure.
In second stage, the lightweight thrust restraint with geogrid and anchor plate was proposed and the effect was proved by model tests. The large-scale tests for new method were carried out in the large pit (8.4 m x 5.4 m x 4 m), using the pipe bend having a diameter 300 mm. As the results, it was clarified that the degree of this effect was depended on the stiffness, length and installation of geogrid.
In third stage, four shaking table tests were conducted in order to verify the safety of the lightweight thrust restraint in liquefied ground. 5Hz sine wave was applied at a peak acceleration of 300gal with taper for duration of 35 seconds. In addition, the weight of 1kN was laterally loaded to the bend of pipelines during the shaking table tests. From the results of the tests, it was concluded that the lightweight thrust restraint backfilled with gravel was sufficiently stable in liquefied ground.
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