Abstract: In order to study the developments of pore water pressure in the liquefaction processes of saturated sands with stratified structure， the liquefaction tests under equal amplitude strain control for saturated sands were carried out by using GCTS-STX-050 dynamic triaxial testing system. The effect of different thickness， position and number of layers on liquefaction was analyzed. It is showed that the cyclic loading times required for liquefaction is non-linearly related to the thickness of the silt interlayer. There is a critical thickness that causes the cyclic loading times to be maximum. And the silt can effectively prevent the transfer of excess pore water pressure generated by fine sand. But the inhibition of fine sand for excess pore water pressure generated by silt is not obvious. Under the same thickness of silt interlayer， the distribution of two-layered interlayer is more obvious than one layer on obstruction of excess pore water pressure. The conclusion can provide a reference for the liquefaction of saturated sand with stratified structure under earthquake.

Key words: saturated sand, stratified structure, equal amplitude strain loading, excess pore water pressure, liquefaction