Effectiveness of micro pile in reducing settlement and tilt of a five-story building on liquefiable foundation soils -Centrifuge modelling

Abstract

Dynamic centrifuge tests were used to simulate seismic performance of a five-story building with footings supported by micro-piles during and after liquefaction process. The comparison test was a shallow-footed five-story building model without piles. The test results demonstrated that small size pile has an obvious effect of restraining the postearthquake settlement and inclination of the building. The deeper the small size pile penetrates into the non-liquefied bearing soil layer, the better the improvement effect. During the shaking, it was observed that the axial instrumented

piles displayed symmetrical reverse axial force waveforms, and the lateral instrumented piles showed similar and in phase bending moment wave forms. After the earthquake, as the excess pore water pressure dissipated, the negative frictional force of the axially instrumented piles increased significantly. Whether it is axial force or bending moment, as the shallow soil liquefies, it increases in the deeper part of the foundation pile, indicating that the shallow soil loses its bearing capacity due to liquefaction and the seismic load is transferred to the deep soil.