The practical meaning of shear tests on rock mass joints

Abstract

In this paper the problem of the meaning of the joint strength tests is analysed in view of the probable hypothesis which says that in Nature, the sliding movements of the joints are more frequent as the discontinuity sizes increase (large joints, faults) and on account of this reason, the morphology of their walls must be mismatched. The paper ends by concluding that the small samples of matched joints with the middle plane in horizontal position provide safe strength values. But if the joints are mismatched, the small samples provide values with doubtful meaning and only "in situ" tests of large samples have some interest and are meaningful.