Shear-induced acoustic emission and energy evolution in granular-filled active waveguide

• Interactions between granular materials and metal waveguides are investigated. • The mechanical state of active waveguides is characterized using acoustic emission (AE) parameters. • AE signals are directly influenced by varying levels of normal stress applied to the waveguide. • A positive correlation is observed between shear stress reduction and AE energy release. • The joint distribution of AE energy and RMS exhibits distinct zonal aggregation patterns. Acoustic emission (AE) technology with active waveguide arrays is an effective method increasingly used for the subsurface deformation monitoring of landslides. However, the generation mechanism and response patterns of AE from an active waveguide remain unclarified. A dedicated direct shear instrument for active waveguides was designed to simultaneously measure various physical parameters for the macroscopic and microscopic analysis of the shear process. The deformation and mechanical behaviour of the active waveguide closely correlate with AE parameters, with distinct response patterns observed across different parameters. Energy parameters displayed considerable variability, with the majority of values concentrated at low levels. The proportion of high-amplitude AE events in the shear process gradually increased, and the energy distribution concentrated towards the high-level. Several small stick–slip events collectively formed a “long stick”, followed by a “large slip”. The AE parameters reached peak values at the slip moment. The shear behaviour of the active waveguide was influenced by particle size, shear velocity, and normal stress. Slower shear velocities exhibited a more pronounced stick–slip behaviour, while normal stress exerted an inhibitory effect on the AE parameters. A foundation was established for the use of AE monitoring to identify deformation and mechanical behaviour, with potential applications in landslide monitoring involving multiple subsurface parameters.