2010 Fiscal Year Final Research Report
Earthquake-induced long-term change of landforms and its implication for rational rehabilitations
| Project/Area Number |
20254003
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 海外学術 |
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| Research Field |
Geotechnical engineering
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| Research Institution | The University of Tokyo |
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Principal Investigator |
KONAGAI Kazuo The University of Tokyo, 生産技術研究所, 教授 (50126471)
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| Co-Investigator(Kenkyū-buntansha) |
TOHATA Ikuo 東京大学, 工学系研究科, 教授 (20155500)
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| Co-Investigator(Renkei-kenkyūsha) |
KIYOTA Takashi 東京大学, 生産技術研究所, 准教授 (70431814)
IKEDA Takaaki 飛島建設, 技術研究所, 研究員 (40443650)
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| Project Period (FY) |
2008 – 2010
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| Keywords | 土石流 / 地震災害 / 復興 / 地形変動 |
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| Research Abstract |
A devastating earthquake occurred in Kashmir, Pakistan on October 8^<th>, 2005. This earthquake resulted from reactivation of a known active fault later defined as the Balakot?Bagh fault, which caused widespread slope failure throughout its stretch. The quake triggered a huge landslide 3.5 km upstream of Hattian-Bala town in the state of Azad Jammu Kashmir of Pakistan. The debris mass blocked two tributaries of the Karli branch of the Jhelum River, and was breached on 9^<th> February 2010. This debris dam provided us with a rare opportunity to keep careful and continuous eyes on its post-earthquake behaviour especially as it was a serious threat to people living along the lower reaches of both the Karli and Jhelum Rivers. The result of this research describes post-formation behaviours of the debris mass, breaching-inflicted changes of not only the debris mass but also both upstream and downstream reaches based upon laser-scanned images of landforms and Differential Geological Positioni
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ng System (DGPS) survey results. The quake was also responsible for a number of debris flows particularly around Muzaffarabad, the provincial capital of Azad Jammu and Kashmir. Quake-induced slope failures resulted in a huge amount of debris material which flows in deeply incised creeks during monsoon and hits the inhabitants along the valley in Muzaffarabad. Two GPS measurements were carried out along with channel morphometric parameters and observed changes to investigate the effect of debris flows along these creeks during monsoon. Other than the physical measurements, actual debris flow was simulated using the Depth Average Material Point Method (DAMPM) after carrying out parametric study and calibrating the model for subject topographical and geological settings. The generalized effect of different input parameters of the model on debris flow runout features was studied and discussed. After ensuring validation of the numerical tool, the contribution of a single closed-type check dam to decrease runout intensity to its downstream reach was also investigated for different locations to obtain optimized selection. Less
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