Different Failure Modes of Sandstone and Shale under Brazilian Tensile Tests

Abstract

Failure modes of rock are difficult and challenging to calculate. It is very important to study the failure modes of rock in the laboratory. After the laboratory study we can understand the different failure modes of rocks. This study can help us to identify the appropriateness of the support designed on the basis of the nature of the work. For that need, this present paper evaluates the modes of rock failure under Brazilian tensile test. In this paper, the different failure modes of sandstone and shale under Brazilian test (Indirect tensile test) are studied. Sandstone and shale samples failed following central, non-central, layer activation and central multiple type of fracturing over the whole range of determined Brazilian tensile strength. From the study it has been found out that the samples failing in central failure mode has the lowest tensile strength whereas the samples failing central multiple mode of failure has the highest strength. The non-central and layer activation mode of failure occurs at moderate strength and the failure departs from the ideal failure due to the presence of weak zones in the rock samples.