Effects of Overconsolidation, Cement Stabilisation, and Unsaturation on the Liquefaction Resistance of Urayasu Sand

Following the 2011 Great East Japan Earthquake and its aftershocks, soil liquefaction and associated phenomena have been widely observed at reclaimed lands along Tokyo bay. Enormous amounts of sand boils were erupted in the city of Urayasu. It is known that the fines content of reclaimed liquefiable soils in Urayasu city varies significantly from 10 to 40–50 %. In the present study, the soil sample erupted as sand boils was retrieved from the city of Urayasu, and multiple series of saturated undrained cyclic triaxial tests are conducted to obtain the liquefaction resistance of fines-containing sand and clean sand without fines. The physical effects of overconsolidation as well as the chemical effects of loosely mixed cement stabilisation are especially examined. In addition, a series of unsaturated undrained cyclic triaxial tests are conducted to obtain the cyclic resistance of fines-containing sand as well as clean sand without fines. The effects of fines on the cyclic resistance of unsaturated Urayasu sand are examined. The effects of overconsolidation, loosely mixed cement stabilisation and unsaturation on the liquefaction resistance of Urayasu sand are then compared and discussed in detail.