Mechanical direct shear tests of cables – combined stress relationships

Cables have remained an integral part of underground mining in Australia since the 1970s and many of their properties are well-researched. However, no standardised test is generally accepted for shear - an important failure mechanism for cables; therefore, this fundamental property is not fully defined. Further, the uncertainty means the relationship between shear load capacity and axial tensile load (pre-tension) is not completely understood. This paper begins to fill the information gap by reporting the results from a new test method. A simple, replicable and valid mechanical direct (90°) shear test method has been developed, that intentionally departs from existing reported methods, by not embedding the cable. The preliminary results show a clear relationship between peak shear load and pre-tension magnitude, by eliminating the numerous variables associated with embedded shear test methods. The mechanical test method can thus be used to determine the minimum shear performance of cables under repeatable conditions, but also augment existing embedded cable shear research, by providing the baseline mechanical properties of the cable.