| Research Abstract |
Shaking table tests were conducted to study dynamic soil-pile- structure interaction during soil liquefaction. A model sand deposit-pile-structure system was constructed in a large container 4m long, 2m wide and 2 m deep. The container, consisting of stacked steel plates, can allow shear deformation of the soil. Shaking table liquefaction tests were then conducted in which soil density, pile diameter, pile rigidity, thickness of the liquefied layer and input motion were controlling variables. Pore pressure, acceleration, and deformation of soil-pile-structure system, and bending moment of pile were monitored and recorded during the test.
The analysis of shaking table test results together with the basic information indicated that: (1) regardless of the rigidity of pile, the dynamic response of the soil-structure system before liquefaction is significantly influenced by the response of soil deposit, (2) unless the pile is rigid enough, the dynamic response of the soil-structure system after liquefaction is also influenced by the response of soil, and (3) the maximum bending moment of the pile is related better to the maximum deformation of the ground surface than to maximum accelerations measured on the structure and the ground surface.
In order to simulate the above findings, analytical method was developed in which regradation of the coefficient of horizontal subgrade reaction of pile due to liquefaction is taken into account as well as the regradation of soil modulus. Analysis was made for both liquefied and non-liquefied cases, and the results were compared with the measured values. The analytical results including the time histories of acceleration, displacement, and bending moment of pile, and the response spectra of the ground surface and structure, are all in good accord with the observed values, showing that the model used in the analysis is reasonable.
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