FEM modelling of self-boring pressuremeter tests on sands by means of Lade's elasto-plastic laws

Two constitutive elasto-plastic laws proposed by Lade, the former in 1977 for sand and the latter in 1988 for sand, clay, rock and concrete, were implemented in CANT-SD and CAN2-SD, respectively a 3-D and a 2-D nonlinear FEM computer program developed by CISE for ENEL-CRIS. The main features of the 1977 model are briefly described in the paper, together with the incremental formulation necessary for its implementation. An essential outline of the mentioned computer programs is also given. The values of the parameters for the 1977 model were determined for a well documented Italian sand (Ticino River Sand), considered at three different relative densities (∽45% ∽75% ∽ 95%), using the results of conventional triaxial compression tests. The performances of the model were checked by comparing experimental and numerical results for a set of Self-Boring Pressuremeter Tests (SBPTs) carried out in a large calibration chamber. Finally, in order to obtain a comparison between the two models (1977 vs. 1988), two additional finite element computations were performed for one SBPT using the parameters given for both models by Lade in the case of the Dense Sacramento River Sand.