Normal loading and direct shear tests
Specimens are selected and are cut to a specified dimension. For pre-existent cracks they are oriented such as they lie in the shear plane and are cast into holders. The area in the shear plane is determined for the shear calculation. The holders with the specimens are mounted in the testing machine and gauges for the deformation measurement are connected. During the test the specimen is loaded in the normal and in the shear direction according to XXX test program, see figure below.
| Example of rock specimen with a natural joint.
Principal picture of the test set-up used at normal loading and shear tests
The results from the tests are from:
Jacobsson, L and Flansbjer, M. Oskarshamn site investigation, Borehole KLX03A, Normal loading and shear tests on joints. SKB-P05-92, Svensk Kärnbränslehantering AB, 2005.
Example of standards
ISRM 1974, Suggested method for laboratory determination of direct shear strength.
ASTM D5607-02, 2002, Standard test method for performing laboratory direct shear strength tests of rock specimens under constant normal force