New mixed boundary true triaxial loading device for testing study on 3-D stress-strain-strength behaviour of geomaterials

A brief review of the true triaxial apparatuses (TTA) developed in the past and their advantages and limitations are presented. Considering the limitations of previous designs, a new true triaxial loading device which provides mixed boundary conditions for a TTA is introduced. A three-dimensional finite element (FE) modelling study is carried out on the stress and strain distribution of a soil specimen subjected to loading from two different loading devices. It is found that the stresses and strains of the soil specimen subjected to loading from the new sliding plates are far more uniform than those subjected to loading from non-sliding plates with preset gaps. Finally, the applications of the present TTA with the new loading device for testing studies on a completely decomposed granite soil and a geofoam are introduced. Typical results are presented and discussed.