Cyclic shear resistance profile of sand deposit improved with sand compaction piles

This paper describes results of site investigations and undrained cyclic shear tests on high-quality undisturbed samples obtained by the in-situ freezing method from the ground improved with the sand compaction pile (SCP). Spatial distributions of SPT N-value and liquefaction resistances were discussed. It was found that N-value and liquefaction resistances in a horizontal plane were considerably heterogeneous. It appeared that the N-value based method for estimating liquefaction resistance used in the current practice is also applicable to the improved ground provided that the ground is fully saturated. However it was revealed that the improved ground contained considerable amount of air. The degree of saturation of the ground was in a range from 78 to 90%. The liquefaction resistance of the sand appeared to be much higher than that estimated from the N-value based method.