Abstract
A new direct shear apparatus for measuring shear strength of soft sedimentary rocks was designed. The features of this apparatus are: 1) friction force between upper and lower boxes is eliminated by controlling the gap between two boxes, 2) effect of friction force between specimen and side wall of the box on the normal stress acted on the failure plane can be corrected by measuring normal load at the upper and lower ends of the specimen, 3) intact rock specimens are able to be tested and both peak and residual strengths can be obtained from one specimen, 4) cyclic shear test with any cycle and magnitude of shear displacement can be performed automatically.
Two series of test were performed with the samples obtained from a site where a landslide occured. Residual strength parameters obtained from the test results using intact specimen almost coincide with those obtained from the results using the specimen consolidated from the state of slurry. The merit of this test apparatus which gives both peak and residual strengths with one specimen was verified from the experimental results.
