Development of the direct shear test apparatus for measuring the shear strength of a soft rock discontinuity and Some results of the measurements

摘要

In-situ shear test using a gadget for measuring the shear strength of a soft rock discontinuity becomes difficult when the gradient of the discontinuity exceeds 30 degrees. In such a case, laboratory test on sampling specimens will be required. However, it is no easy task to set the specimen into the designated shear box in the laboratory. Moreover, if failed in making specimen, going back to the field for re-sampling is required. So, in order to solve these problems, the authors have developed a simplified manual direct shear test apparatus that has a simplicity of setting the specimen, and that is possible to test near the sampling point so as not to go back to the field for re-sampling even if making specimen met with failure. Using this apparatus, a series of shear tests was performed at four fields. At the same time, test results were compared with that obtained from the in-situ direct shear test. From the test results, it was suggested that some improvements leave in this apparatus, but the apparatus has a possibility of practical use.