Measuring and localizing acoustic emission events in snow prior to fracture

摘要: Abstract Acoustic emissions (AE) are transient elastic waves produced by a sudden redistribution of stress in material caused changes the internal structure. In other natural, heterogeneous materials monitoring AE has proven to be valuable tool for stability estimation and failure prediction. After studying characteristics ultrasonic wave propagation snow, we measured acoustic emission signals during snow loading experiments cold laboratory. Using columns found that most energy an artificial signal was transmitted at 31 kHz. Best coupling achieved attaching sensors with silicone adhesive thin aluminium plates which were then frozen snow. Localizing events fracture layered samples showed originated within weakest layer, i.e. relevant layer failure. For finding indication imminent failure, analysed exponent β cumulative size-frequency distribution (‘survival curve’) event energy. At occurrence instabilities, β-curve deviated from steady behaviour exhibited distinct ‘drops’, indicating power law not fulfilled anymore. Studying temporal evolution might therefore provide useful information about snowpack also field—provided too strongly attenuated can detected time before catastrophic occurs.