Liquefaction Testing of Stratified Sands Interlayered with Silt

The cyclic behavior of stratified sands interlayered with silt is at present poorly understood, although stratified sands exist for various soil deposits and hydraulic fill, which have a history of liquefaction during earthquakes. The main objective of this research project was to compare the cyclic behavior of stratified and homogeneous sands for various silt contents. A comprehensive experimental program was undertaken in which stain-controlled undrained cyclic triaxial tests for stratified sand samples interlayered with different thickness silt were performed. The silt thickness ranged from 0 to 80mm was considered. The confining pressure in all test series was 100kPa. The results indicate that the thickness of the silt seam sandwiched in the sand samples has a significant influence on the liquefaction resistances of layered sands. In other words, there is a critical thickness of silt seam that the saturated stratified sands have a critical shear strain. This finding justifies applying the laboratory tests results of homogeneously reconstituted samples to the field conditions for the range of variable studied.