True triaxial tests on unsaturated soils with suction-controlled condition

Based on the new true triaxial apparatus of Xi’an University of Technology, the pedestal of the pressure chamber is installed with a high-air-entry-value ceramic disk and porous plate is placed on the top of the specimens. Thereby, the pore-gas pressure and pore-water pressure can be independently controlled and measured. Thus the axial translation technique is used to control the matric suction. In addition, the true triaxial apparatus is newly equipped with a water-air control panel unit and the pneumatic duplex pieces, which makes the true triaxial apparatus further improvement to control suction. On this basis, the consolidation drainage true triaxial tests are firstly conducted on the remolded loess with suction and net mean stress controlled condition. During the tests, the matric suction (s=100 kPa) and the net mean stress (p= 300 kPa) are kept constant. The measured curves of variation of deviatoric stress (q) versus major, intermediate and minor principal strains (,,) are analyzed under different intermediate stress parameters (b=0,0.25,0.5,0.75,1). In addition, the failure loci of the remolded loess on -plane are given, and the comparision is made between the experimental results and the predicted failure loci of Lade-Duncan failure criterion and Mohr-Coulomb failure criterion.