Mechanism of Liquefaction in Layered Soils

摘要

Results from six centrifuge model tests are presented. Four of the model testsinvolve layered soil deposits subject to base shaking; two model tests involve uniform soil deposits of sand subject to base shaking. The layered soil models consisted of a saturated liquefiable fine sand overlain by a layer of relatively impermeable silica flour (silt). Pore water pressures, accelerations, and settlements were measured during all six tests. Results from the model tests involving layered soils suggest that during liquefaction, a water interlayer or very loose zone of soil develops between the sand and the silt due to the difference in permeabilities. Soil volcanos or boils were seen on the surface for all four of these layered model tests. The locations of these boils, in each test, were found concentrated in the weakest zones of the overlying silt layer; cracking of the weak silt zones provided a release or a vent for the excess pore water pressure generated as a result of particle rearrangement in the liquefiable fine sand. Dynamic testing, geotechnical centrifuge models, liquefaction, pore pressure, sand boils, failure mechanisms.