Liquefaction of heterogeneous sand: Centrifuge study

From past numerical research and small scale laboratory tests, it has been observed that more excess pore water pressure (EPWP) is generated during earthquakes in a heterogeneous sand deposit than in the corresponding homogeneous sand with relative density equal to the average relative density of the heterogeneous sand. This interesting phenomenon is investigated here in large scale experiments using geotechnical centrifuge modeling techniques. A series of liquefaction tests have been conducted at C-CORE's geotechnical centrifuge facility: Two on variable sand and one on uniform sand deposits. A one level frame structure resting on two strip footings was also placed on that sand deposit to study the effect of soil variability on building foundations. Experimental results such as accelerations, EPWPs and settlements were monitored and measured throughout the tests. Recorded results support the conclusion of previous research that more EPWP is generated in heterogeneous sand deposits than in the corresponding homogeneous sand. The liquefaction mechanism of heterogeneous sands leading to this phenomenon is discussed in this paper. Copyright © 2010 by ASTM International.