Book Description

Laboratory studies of soil behavior during rotation of principal stress directions may be performed using a torsion shear apparatus. The requirements, construction, and operation principles for this apparatus are presented. The same confining pressure is applied to the inside and outside surfaces of a hollow cylindrical specimen. Both clockwise and counterclockwise shear stresses and vertical deviator stresses can be applied to the ends of the hollow cylinder. The entire setup is contained in a pressure cell, and the integrated loading system is located below the table which holds the cell. A variety of initial stress conditions may be used, and the behavior of soils during large stress reversals, as well as reorientation of principal stresses and combinations of these conditions, may be investigated in this apparatus. The loading system and the deformation measurement principles are described, and procedures for preparation of sand specimens are presented. The advantages and limitations of the torsion shear apparatus are discussed.