displacement computation of cutoff wall of second-phase cofferdam in Three Gorges project

shows that the parameter of unloading modulus in Duncan-Chang nonlinear elastic E-ｕmodel has a fairish influence on precision of calculation .It is known by experimental data that the coefficient of loading modulus is dependent on component and density of every kind of soil

and was obtained the empirical relation between loading modulus parameter and unloading modulus parameter from the experimental curve .So

unloading modulus parameter can be determined directly from loading modulus coefficient

which coheres with practical circumstances in general .