**Description of the problem**

One of the advantages of *ELPLA * is that the bilinear relation of deformation for the modulus of compressibility can be taken into consideration. Therefore, an example was carried out by the Modulus of compressibility method (7) to show the influence of overburden pressure on the settlements, contact pressures and moments.

A square raft has the dimension of 18×18 [m^{2}] under an elevated water tank was chosen as shown in the Figure.

For comparison, * ELPLA *was used to study the influence of overburden pressure (*q*_{v}, *W*_{v}) on the values of settlements, contact pressures and moments for the following three different assumptions:

a) Without taken into consideration the influence of overburden pressure, where the modulus of compressibility for reloading *Ws * of the soil is taken to be equal to that of loading * E*_{s}.

b) The modulus of compressibility for reloading *W*_{s} of the soil is very great (*W*_{s }= 9×10^{8 } [kN/m^{2}]), where the settlement due to the reloading of the soil is nearly zero.

c) The modulus of compressibility for reloading * W*_{s} = 12447 [kN/m] is three times as the modulus of compressibility for loading * E*_{s} = 4149 [kN/m], where the bilinear relation of deformation for the modulus of compressibility is taken into consideration.

Example 20: Influence of overburden pressure