ABSTRACT
Ground settlement may occur due to ejecta during soil liquefaction and consequently cause damages to structures and lifelines. To investigate factors that affect the settlement induced by sand boil, an experimental investigation by the special design apparatus is conducted in this study. Sandy deposit is prepared by filling in transparent acrylic cylinder with varying densities and fines contents. An acrylic circular plate, acting as a non-liquefied layer, is placed on the top of sandy deposit (specimen). Then, the cylinder is subjected to torsional shaking to produce soil liquefaction and sand boil. Soil particles are ejected out from the gap between the circular plate and cylinder and the plate starts to sink simultaneously. The thickness of ejecta can be observed from the accumulated sand particles on the plate. The influences of varying densities and fines contents on the ejecta amount as well as the settlement are quantitatively analyzed. It is found that the larger density of clean sand deposit results in smaller ejecta amount and associated settlement. However, the influence of density on the ejecta amount of sand and silt mixture is not as obvious as that of clean sand. Moreover, the ejecta contains more silt than the prepared specimen from the sieve analysis results.
