Acoustic emission monitoring in geotechnical element tests

Acoustic emission (AE) is high-frequency noise (>10kHz) generated by deforming materials. AE is widely used in many industries for non-destructive testing and evaluation; however, it is seldom used in geotechnical engineering, despite evidence of the benefits, because AE generated by particulate materials is highly complex and difficult to measure and interpret. This paper demonstrates that innovative AE instrumentation and measurement can enhance insights into geotechnical element tests. Results from a programme of triaxial compression and shear, large direct-shear and large permeameter experiments show that AE can be used to characterise mechanical and hydromechanical behaviour of soils and soil-structure interaction, including: dilative shear behaviour; transitions from pre- to post-peak shear strength; changes in strain rates; isotropic compression; unload-reload cycles of compression and shear; and seepage-induced internal instability phenomena.