Ring Shear Test

The Ring Shear machine is a torsional shear device that allows accurate and repeatable test results to determine Residual and Fully softened shear strengths of cohesive and fine-grained soils using ASTM D7608 and ASTM D6467, respectively. In the case of residual shear strength measurement, rotational shear action is applied continuously until a constant residual strength value is achieved. The advantage of a ring shear test is that the cross-sectional area of the shear plane remains constant during the test.

• Maximum Shear Stress = 1000 kPa
• Maximum Normal Stress = 1000 kPa
• Rotational Speed = 0.001 to 1000 degs/min
• Sample Size = 100mm outside, 70mm inside & 5mm thick
• Dimensions (W x D x H) = 1335 x 380 x 1400mm
• Weight = 105kg

The ring shear test is suited to the relatively rapid determination of drained residual shear strength because of the short drainage path through the thin specimen, and the capability of testing one specimen under different normal stresses to quickly obtain a shear strength envelope. Also, the ring shear test is suited to the determination of the drained fully softened shear strength because of the short drainage path through the thin specimen, small post-peak strength loss in a normally consolidated specimen, and the constant cross-sectional area.

Residual shear strength values are used which is important when analyzing the stability of slopes that contain a preexisting shear surfaces like old landslides, soliflucted slopes, sheared bedding planes, and joints and faults. The fully softened shear strength is important to analyze the softened strength of over-consolidation clays, claystones, mudstones, and shales that do not have a pre-existing shear surfaces, shear bedding planes, joints or faults, and un-failed compacted fill slopes.

• Hoyos, Laureano R., Claudia L. Velosa, and Anand J. Puppala. “Residual shear strength of unsaturated soils via suction-controlled ring shear testing.” Engineering geology 172 (2014): 1-11.
• Hoyos, Laureano R., Claudia L. Velosa, and Anand J. Puppala. “A servo/suction-controlled ring shear apparatus for unsaturated soils: Development, performance, and preliminary results.” Geotechnical Testing Journal 34, no. 5 (2011): 413-423.