Dependence of Glacier's Adhesion on Bedrock Properties: The Role of Porosity and Wettability

Abstract

The strength of the glacier–bed interface plays a critical control over glacier dynamics. Previous studies have examined the effects of factors such as temperature and interfacial roughness on the mechanical behavior of the ice–rock interface, whereas the impact of bedrock properties remains relatively underexplored. Using a centrifugal apparatus, we measured the adhesion strength of ice on bedrocks with varying properties. Rock porosity and surface wettability were identified as the primary controlling factors. Experimental results show that variations in bedrock porosity and wettability can lead to maximum differences in the ice adhesion strength of up to 1.5‐fold and 1.25‐fold, respectively. Micro‐rhizoidal ice structures observed via cryo‐electron microscopy at the ice–rock interface suggest an “ice‐root effect” as the underlying mechanism responsible for the enhanced ice adhesion on high‐porosity rock substrates. Analyses demonstrate that the ice‐root effect is governed by the contact area between ice roots and pore walls. On this basis, we proposed a parameter termed the ice‐root contact area coefficient, f _{A , ir} , to quantitatively characterize the ice‐root effect. Experimental data further reveal a strong linear correlation between ice adhesion and f _{A , ir} . Regarding rock wettability, a strong linear correlation was observed between ice adhesion and the static water contact angle (WAC) θ ₀ of bedrock, indicating that θ ₀ can be regarded as the optimal parameter for describing the wettability effect. This study provides a quantitative framework for understanding and evaluating the influence of bedrock properties on the mechanical behavior of the ice–rock interface.