Modélisation constitutive du comportement cyclique des sables en condition drainée

Considerable strains appear in the structures at the time of the irreversible strains accumulation of the foundation soil under the effect of the cyclic loads. If the number of cycles is very high even "small strains" after accumulation become important and sometimes harmful. In this study, a simple numeric modelling of the behaviour of the sands under cyclic loading is proposed. The proposed approach attempts, in drained condition, to determine the parameters characterizing the average cyclic path of soil under the effect of N cycles duly characterized, and to explain the cyclic effect by an accumulated volumetric strain as well as by a variation of the soil modulus. In this survey, triaxial cyclic tests are simulated by means of a calculation by Finite Elements Method using the Plaxis program. The determination of identification parameters of the first cycle (load-unload) realised step-by-step was achieved by taking the HSM model as the behaviour model of soil. Then the behaviour after N cycles (N > 103) is simulated by the proposed formulation as a pseudo-flow. The comparison of the proposed method to several triaxial cyclic tests confirms the good adaptation of the proposed model to this type of problems.