Study of liquefaction characteristics of saturated stratified sands by dynamic triaxial test

Liquefaction strength tests for saturated stratified sands with different silty layer thicknesses were carried out by dynamic triaxial testing machine under constant stress amplitude cyclic loads.The deformation and mechanical properties for clean sand and stratified sand with different silty layer thickness were analyzed.The experimental results show that the development law of pore water pressure for stratified silty sands are different from clean sands due to the special soil structure;the liquefaction resistance strength of saturated stratified silty sands does not increase monotonously with the thickness of silty soil layer,but there is a critical thickness.However,the liquefaction resistance strength increases monotonously with the thickness increasing above the critical point;the critical shear strains are different under different liquefaction criteria and different cycle numbers,such as the critical shear strain under the criterion of =1.0 is larger than that under the criterion of =0.9.Besides,the critical shear strain should not be a constant under different earthquake magnitude and intensity.The silty interlayers influence the liquefaction characteristics of stratified silty sands greatly and can simulate the liquefaction characteristics of stratified sands in natural environment better.