SEISMIC SOIL-STRUCTURE INTERACTION OF CROSS SECTIONS OF FLEXIBLE UNDERGROUND STRUCTURES SUBJECTED TO SOIL LIQUEFACTION

The soil-structure interaction of underground structure was studied considering soil liquefaction of the backfill soil. A series of 1G shaking table tests was conducted on an aluminum fixed base structure model embedded in saturated cohesionless soil. A special attempt was made to experimentally build a stress-strain relationship as well as an effective stress path of soil around the embedded structure by installing a variety of transducers for acceleration, displacement, pore pressure and earth pressure. Moreover, earth pressure and bending strain of the flexible wall of the embedded structure model were measured. The time histories of shear modulus of liquefied soil, amplification of shaking, and the phase difference between displacement and earth pressures on the structureʹs side face were recorded. It was observed that the natural period of the ground along with structure and the dilative nature of the soil significantly affect the type of soil-structure interaction around the studied embedded structure. The problem of the determination of dynamic pressures on a flexible wall during liquefaction is solved analytically considering the dynamic feature of embedded structure observed in a series of shaking table tests. Finally, a comparison is made between measured and calculated dynamic pressure for several test results in order to show that the proposed solution of dynamic pressure on flexible wall gives good results.