1. ASTM, 2006. Standard test method for torsional ring shear test to determine drained residual shear strength of cohesive soils (ASTM D 6467-06a). ASTM, West Conshohocken.
2. ASTM, 2010. Standard test method for torsional ring shear test to determine drained fully softened shear strength and nonlinear strength envelope of cohesive soils (using normally consolidated specimen) for slopes with no pre-existing shear surfaces (ASTM D 7608-10). ASTM, West Conshohocken.
3. A new ring shear apparatus and its application to the measurement of residual strength;Bishop;Géotechnique,1971
4. Clay mineralogical approach to the slip surface formation in the O’dokoro landlside, Niigata, Central Japan;Egashira;Clay Sci.,2000
5. Ring shear apparatus for measuring residual strength and measurement accuracy;Gibo;J. Jpn. Landslide Soc.,1994