Internal instability mechanism of glacier deposits: insights from seepage deformation experiment

Glacial deposits, formed through glacial erosion, transportation, and accumulation, are exposed in significant quantities because of global warming, serving as potential sources of hazardous geological events. This study undertook a comprehensive analysis of glacial deposits in the upper reaches of the Yi'Ong Zangbo River in Tibet, China. Through field investigations, original sample seepage deformation failure experiments, and laboratory experiments, the formation mechanisms and permeability properties of glacial deposits in this basin were explored, with particular emphasis on the effect of fine particle loss on their permeability characteristics. The findings revealed that the glacial deposits in the Xibengnongba basin of the Yi'Ong Zangbo river were formed during the Quaternary glacial period and exhibited a unique initial structure influenced by glacial transport. Based on the Q –i curve derived from the seepage deformation experiment, the glacial deposits seepage process was categorized into the stable seepage stage, internal suffusion stage, and failure stage, with evident piping and localized fine particle migration observed during the internal suffusion stage. Furthermore, due to the disturbance of the original structure, the reconstructed glacier deposit demonstrated lower critical hydraulic gradients and higher levels of fine particle loss.