2018 Fiscal Year Annual Research Report
Impedance functions of an interlocking Steel Pipe Sheet Pile (SPSP) caisson foundation under nonlinear soil-structure interaction (SSI)
| Project/Area Number |
17K14713
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| Research Institution | Saitama University |
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Principal Investigator |
Goit Chandra 埼玉大学, 理工学研究科, 助教 (10782732)
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| Project Period (FY) |
2017-04-01 – 2019-03-31
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| Keywords | SPSP foundation / Nonlinear behavior / SSI / Impedance functions / Kinematic interaction |
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| Outline of Annual Research Achievements |
Nonlinear dynamic response of a soil-steel pipe sheet pile (SPSP) foundation is studied through physical scaled model testing under 1g conditions, accounting for the soil-structure interactions (SSI) effects. A circular 1/16.5 model SPSP foundation comprising of 20 hollow circular aluminum pipes (outer diameter = 30 mm and wall thickness = 2 mm) with lengths of 960 mm and embedded in dry cohesionless soil was considered. Kinematic interaction factors (KIF) and head impedance functions (IFs) for a wide range of lateral harmonic accelerations (to induce low-to-high strain levels in the soil) was obtained for a broad range of frequencies. For low loading amplitudes, KIF values are found close to unity for low frequencies of loading while smaller for higher frequencies. However, as the loading amplitude increases, KIF values are found to be larger than unity at lower frequencies. As for the IFs, results show a significant dependency on soil’s strain level. With the increase in the input loading amplitude, i.e., increase the strain level in soil, the real part of IFs (stiffness) decreases. The imaginary part of IFs (damping), on the other hand, increases with the increase in the loading amplitude; the radiation damping becomes significant for each amplitudes in the higher frequencies. Results obtained through this work signify that both the KIF and IFs (essential components for SSI calculations) are dependent on material nonlinearity. Carried out work provides a detailed insight into important aspects of dynamic behavior of SPSP foundations.
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