2007 Fiscal Year Final Research Report Summary
Study on deformation of subsurface layer by faulting and mitigation of damage to structures due to fault displacement
| Project/Area Number |
17560421
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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 |
Structural engineering/Earthquake engineering/Maintenance management engineering
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| Research Institution | Saitama University |
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Principal Investigator |
TANIYAMA Hisashi Saitama University, Graduate school of science and engineering, assistant professor (80236710)
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| Co-Investigator(Kenkyū-buntansha) |
SAITO Masato Saitama University, Graduate school of science and engineering, associate professor (40334156)
MAKI Takeshi Saitama University, Graduate school of science and engineering, associate professor (60292645)
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| Project Period (FY) |
2005 – 2007
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| Keywords | surface-breaking fault / fault displacement / strike-slip fault / Riedel shears / DEM / 2000 Tottori-ken-seibu earthquake / nonlinearity |
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| Research Abstract |
The following research results were obtained. 1. Stress change history of the 2000 Tottori-ken Seibu earthquake was estimated directly from the observed strong motion records. It was hind that the large stress drop occurred in the upper central part and lower part of the fault and that the stress dropped monotonically within 1-1.5 s. 2. Development of shear bands in the subsurface layer due to strike slip fault was examined using DEM analysis. In the sediment model of distinct elements, concave-upward shear zones which developed from the basement fault on bath sides of the fault were observed first and were followed by a helicoidally shaped shear. The helicoidally shaped shear (Riedel shear) propagated through the sediment model and broke the surface. With increasing basement displacement, shear zone striking at lower angle to the basement fault developed at surface. The geometry and sequence of these shears agreed with those observed in sandbox tests. It was hind that the development of ship shape structures (shear zones which developed from the basement fault on both sides of the fault) and Riedel shears was attributable to the stress due to dilatancy and the shear in the vertical plane along with the lateral shear. 3. Model tests of strike slip fault showed that the location and amount of slip farmed in model sediments due to basement fault changed by replacing part of the model sediment with ground material which had different properties. 4. 3-D finite element analyses were carried out to investigate the seismic response of piles. Nonlinear material properties and interaction were incorporated. It was shown that the numerical analysis simulated fairly well the actual behavior of pile-soil system with proper consideration of nonlinear material property and that the dynamic and static analyses gave different ground strain.
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