2002 Fiscal Year Final Research Report Summary
Investigation on Lifeline fragility and disaster mitigation methods related to surface fault rupture during the chi-chi Earthquake
| Project/Area Number |
13574002
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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 | 海外学術 |
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| Research Field |
構造工学・地震工学
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| Research Institution | Kobe University |
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Principal Investigator |
TAKADA Shiro Kobe University, Faculty of Engineering Professor, 工学部, 教授 (40027280)
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| Co-Investigator(Kenkyū-buntansha) |
MIYAJIMA Masakatsu Kanazawa University, Faculty of Engineering Professor, 工学部, 教授 (70143881)
SATO Tadanobu Kyoto University, Disaster Prediction Research Institute Professor, 防災研究所, 教授 (00027294)
TANAKA Yasuo Kobe University, Research Center for Urban Safety and Security Professor, 都市安全研究センター, 教授 (40144597)
KAWAKAMI Hideji Saitama University, Geosphere Research Institute Center Professor, 工学部, 教授 (50125887)
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| Project Period (FY) |
2001 – 2002
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| Keywords | Fault / Pipeline / Phase / Experiment / Maximum acceleration ratio / Digital soil data / Shell analysis / countermeasures |
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| Research Abstract |
Dynamic analyses for 3-D ground model considering 3-D variation of underground soil structures have been performed. This model is considered to be effective in analyzing strong ground motions and dislocation in the vicinity of active faults.
A phase characteristics is modeled by using an index of a group delay time obtained by observed acceleration records. Results show that an average of the group delay time changes depending on a radius from an epicenter and the standard deviation of the group delay time is affected by the directivity of rupture.
An average and standard deviation of a ratio of the maximum acceleration at arbitrary two points are obtained using many observed acceleration records to check the variation of the maximum acceleration for one earthquake. The standard deviation is turned out to be proportional to the logarithm of separation distance between two points.
A dislocation of ground surface is experimented by using model soil layer under fault displacement at a base rock. The results show that a shear zone occurs both at upper hanging walls for soft soil layer, but only hanging wall for hard soil layer.
Performance of a fault crossing pipeline is analyzed by a shell FEM. Computational results show that a cross angle between pipeline and fault rupture line gives an important effects to the behavior when the cross angle is more than 90 degrees.
By carrying out a parametric study by employing the shell FEM, a design formula for the maximum pipe strain is obtained for three different cross angles.
Existing countermeasures for pipelines crossing faults are introduced and also, several countermeasures are proposed based on the new design formula. It turned out that software countermeasures are required for large fault displacement, besides hardware countermeasures.
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