ringshear

Ringshear refers to a laboratory test and the apparatus used to measure the shear strength of soils and similar materials by imposing shear along a circular slip surface. The test is conducted on a ring-shaped specimen placed between a stationary inner boundary and a rotating outer boundary, with a controlled normal stress applied to the sample.

In a typical ringshear setup, a soil sample is confined in an annular ring. A normal load is applied to the top or through a loading system to mimic in situ confinement. One of the rings is rotated gradually to generate shear along the circular slip plane. The apparatus records shear force and horizontal displacement (or strain) as the test progresses, producing a shear stress–displacement curve.

The ringshear test provides information on peak and residual shear strength of the material. From the data, engineers can derive strength parameters such as frictional resistance and, for cohesive soils, cohesion, under a specified normal stress. The method is particularly useful for rapidly obtaining large-strain behavior and for materials that may not behave well under conventional direct shear or triaxial tests. It is commonly employed in assessing the stability of slopes, embankments, tailings deposits, and dredged materials, as well as in research on post-peak strength and dilatancy.

Limitations include sensitivity to boundary conditions and sample preparation, potential slip surface effects, and the need for careful interpretation when comparing with other test methods. Ringshear remains a practical tool for evaluating shear properties under controlled, large-strain conditions.