Finite element method is a familiar method in the calculation of embankment settlement

but it has difficulties in deciding model parameters. Generally

this needs doing triaxial drained test. In order to make this method be practical

some error analyses

which are concerned about the existing simple method for determining tangential elastic modulus of Duncan-Chang model

are done and related modified coefficient is also brought forward. Furthermore

an approximate formula for determining tangential Poisson ratio

suitable for both sandy and cohesive soils

is given according to the K0 status of soils. Example shows that the above methods have definite reference value in common road engineerings which need settlement calculation with FEM but lack of triaxial test materials.