Author(s): Jiahui Gao; Yuxiang Zhang; Zhinan Xie; Dingyi Ma
Linked Author(s):
Keywords: Sea Ice; Ice Mechanics and Properties
Abstract: The mechanical properties of ice are severely affected by environmental factors such as temperature, off-line assessment methods are often laborious and yet in-accurate, whereas the hard condition of the Arctic poses a great challenge for performing a quasi-static measurement on site. In this manuscript, an in-situ method for the characterization of sea ice’s acoustic parameter, which can be directly linked to its mechanical properties, is proposed by combining the use of elastic guided waves and polarization filtering. Based on the use of three-components seismometers and an artificial hit on the ice surface, elastic guided waves of multiple modes are generated at low frequencies and recorded. The resulting wavefields are, however, the superposition of energies from different modes in both temporal and frequency domains. The signal processing based on polarization filtering is thus applied to such multi-components multi-modal seismic records, and the resulting wavefield separation allows one to extract propagation velocity of shear waves and longitudinal plate waves, from where the velocity of bulk longitudinal wave can be further estimated. Experimental validation has been conducted on the ice over Songhua River using a non-directional acoustic source and seismometer array, the results show an improvement in accuracy, robustness, and practicality, which are further compared with those of sea-ice documented in the literature. The group velocity of flexure waves is also estimated and discussed.
Year: 2022