Experimental study on the shear strength and failure mechanism of mountain glacier ice

Abstract. As global warming increases the frequency of ice avalanches, understanding the mechanical behavior of mountain glacier ice becomes critical. Through more than 250 field and laboratory tests, the variations of four kinds of glacier media with temperature and debris content were analyzed. The four types of glacial media are polycrystalline ice, ice-rock composite, fine debris ice, and coarse debris ice. Our comprehensive analysis reveals a positive correlation between ice density and debris content, but with a notable nonlinear decrease in porosity as debris content escalates. All types of ice have strain-softening characteristics in the shearing process. Shear strength is significantly modulated by debris content and temperature gradients. Fine debris ice exhibits the highest strength, followed by coarse debris ice, polycrystalline ice, and ice–rock composite. Polycrystalline ice displays the strength of nonlinear degradation with increasing temperature and ice– rock composite shows the strength of linear degradation with increasing temperature. Fine and coarse debris ice display the strength of the nonlinear enhancements with increasing debris content. The mechanism by which the strength of polycrystalline ice and ice-rock composites decreases with temperature increases is discussed. The strength enhancement of debris ice caused by increased debris content is expounded. It is believed that the emergence of liquid water is one of the reasons for the strength degradation. The solid particle effects (biting, friction, and crushing) are essential reasons for strength enhancement. This study addresses the research gap in mountain glacier ice mechanics driven by global warming, a previously underexplored subject. This investigation expounds on the nuanced interdependencies between temperature and debris content in determining glacier ice' shear strength, paving the way for force avalanche prediction models and disaster prevention strategies. It provides pivotal insights into mountain glacier ice behavior under different environmental conditions.