3D TRIAXIAL SIMPLE SHEAR TEST
The 3D Triaxial-Simple-Shear (TxSS) apparatus was designed and manufactured to permit the application of monotonic loading as well as both regular and irregular shear stresses or strains to soil specimens. The TxSS device was designed to test cylindrical soil specimens with a diameter of 63 mm or 80 mm and varying heights in a triaxial pressure cell so that confining pressure and back pressure can be applied and monitored. The specimen is located between relatively rigid bottom and top caps and is typically confined by a rubber membrane. The bottom and top caps that contain fine porous stones provide a “frictional” surface while allowing for drainage into the porous stones. A computer-automated feedback-loop-controlled system provides an excellent control of stresses and strains. The TxSS system permits the direct measurement of the pore water pressure generation during the undrained shear test. It also provides the opportunity for geotechnical engineers and researchers to test undisturbed and reconstituted soil samples under either isotropic or anisotropic loading conditions. The TxSS can be simply reduced to the DSS if the soil sample, prepared in a membrane-enclosed space, is surrounded by stacks of annular plates (rings) and a zero-confining pressure is applied. A new reinforcement method was also developed in the geotechnical laboratory at the Université de Sherbrooke, using fiberglass tape . This method appears effective to confine the soil sample laterally without the need of specialized equipment as in the case of the armed membranes with iron wires.