The GDS Standard Simple Shear (STDSS) testing
system is a stand alone simple shear device with no requirements for
compressed air or hanging weights.
A cylindrical soil specimen is laterally confined by Teflon
impregnated low friction retaining rings, ensuring a constant cross
sectional area. A shear force loading is then applied. Vertical
displacement is prevented using active height control (via the axial
force actuator), therefore constant volume conditions are enforced (i.e.
Simple Shear).
The STDSS apparatus allows for a smooth and continuous rotation
through 90 degrees of the principal stress directions. The ability
to simulate principle stress rotation is common to many geotechnical
problems, including earthquake loading. The simple shear device
allows direct investigation of the shear stress v. shear strain in
drained and undrained situations.
