The secant shear modulus of lightweight sand-EPS beads soil (LSES) under dynamic loads will degrade with increasing strain. Based on cyclic triaxial test data on LSES of different cement contents and EPS contents

a degradation model of Gsec is set up relating to factors such as confining pressure

shear strain and cement content. After comparison

the Gsec model of LSES is similar with those of sand and cemented sand

that is

Gsec-?d is hyperbolic and Gsec is linear to . Additionally

due to the bonding effect of cementation

the confining pressure dependency of Gsec decreases with increasing cement content

which is responded by the parameter n. While cement content reaches to 10 %

the variation of n is not clear. This is because cementing strength increases to the level which makes the relative location between particles of LSES uneasy to change.