Dynamic Tensile Failure of Rocks Under Triaxial Stress State

Abstract

Tensile failure of rocks is a main problem in underground engineering projects, in which rocks are subjected to dynamic disturbances while under in situ stresses. When disturbed by dynamic loads from blasting, seismicity or rock bursts, the underground structures under static pre-stress would be vulnerable to tensile failure. A modified split Hopkinson pressure bar (SHPB) system is adopted to load Brazilian disc (BD) specimens statically simulating the in-situ stress state, and then exert dynamic load generated by impact. Several groups of specimens are tested under triaxial stress state. The dependence of dynamic tensile strength of the rock material on the static pre-stress and loading rate is established. The result shows that the dynamic tensile strength of the rock increases with the loading rate, revealing the rate dependency. It also shows that the dynamic tensile strength decreases with the increasing pre-tension but increases with the hydrostatic confinement.