Author(s): Qingkai Wang; Kunsen Liu; Matti Lepparanta; Bin Cheng; Linsheng Huo; Yubo Liu; Peng Lu; Zhijun Li
Linked Author(s): Zhijun Li, Matti Leppäranta, Peng Lu, Yubo Liu, Qingkai Wang
Keywords: Microcrack evolution; Acoustic emission; B-value; Natural ice; Ductile deformation
Abstract: Ice exhibits ductile deformation under uniaxial compression at low strain rates, a regime critical for ice-structure interaction and geophysical processes, with defects (gas bubbles and brine pockets) critically influencing microcrack development. To investigate the damage mechanisms governing the ice ductile deformation, uniaxial compression tests were performed on natural columnar ice sampled from a brackish lake (ice sample salinity averaged 0.9 ppt) under varying strain rates (10−6 s−1 to 10−4 s−1), temperatures (−12 °C to −3 °C) and loading directions relative to the crystal columns. Acoustic emission (AE) signals were continuously monitored using four sensors, from which parameters such as count rate, energy, and amplitude were extracted, and three-dimensional AE source locations were determined to trace spatiotemporal microcrack evolution. On the basis of AE activity, microcrack development was divided into four characteristic stages: initial nucleation, stable growth, rapid propagation, and post-failure. The results revealed that low strain rates facilitated an extended stable stage and low-energy microcracking, while high strain rates triggered diffuse, high-energy microcracking and the absence of a stable stage. The b-value was determined using AE signal amplitudes to reflect cracking intensity and scales, with higher values linked to low-amplitude signals and small-scale crack dominance, and generally decreased with increasing strain rate. Temperature effects were linked to creep, with elevated temperatures enhancing creep and promoting dispersed low-energy microcracks, whereas lower temperatures suppressed creep and favoured localized, high-energy damage. Loading parallel to the ice columns caused earlier microcrack initiation and pervasive propagation than loading perpendicular. Overall, these findings establish a linkage between microcrack activity and the macroscopic mechanical behavior of ice, which is helpful for advancing understanding of ice-structure interaction and contributing to research in ice geophysics.
Year: 2026