Acoustic And Failure Behaviour Of Gondwana Shale Under Uniaxial Compressive And Indirect Brazilian Tensile Loading-An Experimental Study

Shale has become a principle source of future energy in India. Therefore, research on mechanical and fracture behavior of shale rock has proven imperative in rock engineering. The present study investigated significance of acoustic behavior in shale rock under constant uniaxial compression and tensile Brazilian loading. The XRD and SEM analysis revealed that the investigated shale samples exhibited natural flaws at micro levels with higher percent of flaky micaceous minerals. The compaction of laminations and microstructural flaws is evident during the compression than in tensile condition. This was marked by gradual acoustic rate increase during the preliminary stages in compression. However, the rate of acoustic emission in medial time sequence is feeble under both loading conditions. This indicated the damage accumulation with associated deformation. The stress increase seems to have initiated propagation of fractures leading to failure of rock witnessed by steep increase in acoustic data at final stages. Likewise, tensile failure under Brazilian loading was observed with burst of acoustic signals. The acoustic patterns revealed that layering in shale failure during compression and tensile loading. The present study tried to understand the failure behavior of shale through acoustic emission parameters to infer fracture initiation and propagation stages. The research can be extended to study the fracture stimulation in shale gas exploration and CO2 injection as an aid to understand shale behavior under compression and tensile loading.