Monnet Boutonnier (2024) Interpretation of the pressuremeter test into clay in unsaturated and undrained condition - ICSC24
The pressuremeter allows to measure a pressuremeter modulus and a limit pressure, which are used to estimate the bearing capacity of the foundation with different standards , the results of the pressuremeter test are the pLM limit pressure and the EM pressuremeter modulus. These quantities cannot be entered as data in a geotechnical calculation by Finite Elements or Finite Differences for the study of Civil Engineering works (retaining walls, tunnels, embankments, embankments, excavations, etc.). These modern calculation methods require, at a minimum, knowledge of the effective mechanical characteristics of the soil, in elasticity (with the Young's modulus E and the Poisson coefficient ) and in resistance (with cohesion c’ and the angle of friction '). This study is devoted to the interpretation of the pressuremeter test so that it is possible to use it for the determination of the effective mechanical characteristics of the soil. When the pressuremeter test is carried out into clay, it appears pore pressure during the test when only shearing is applied. This study explains the apparition of pore pressure (related to non linear elasticity); shows the importance of an Effective interpretation of the measurements to determine the shear modulus which can be 20 times lower than the one determine if pore pressures are not accounted for. This paper gives also the theoretical value of the Skempton coefficient B applied to the pressuremeter in elastic and plastic conditions and finally gives a first application of the theory by comparison with a pressuremeter test performed in London clay at 20.6m depth.