Temperature and Strain Rate‐Dependent Mechanical Behavior of Ice‐Sandwiched Rock Mass Under Uniaxial Compression

ABSTRACT In high‐altitude mountain permafrost regions, the bedrock is commonly in a permanently frozen state with joints or fractures filled with ice. An in‐depth understanding of the temperature and strain rate‐dependent mechanical behavior of frozen bedrock is urgently needed to deal with the rock slope hazards in such regions. In this study, uniaxial compression tests are carried out on ice‐sandwiched rock mass at different temperatures and strain rates, and the failure process is observed by acoustic emission (AE) system and a high‐speed camera. The results show that (1) the mechanical behavior of ice‐sandwiched rock mass shows strong temperature dependency, as it decreases with increasing temperature following a three‐stage trend. Two critical temperatures, −6°C and −1°C, mark the transition from brittle failure to ductile failure and back to brittle failure again. (2) There is a strong strain rate dependency in the mechanical behavior of ice‐sandwiched rock mass as well. The strength increases first and then decreases with the increase of strain rate, reaching the maximum value at the strain rate of 1 × 10 −3 s −1 . Meanwhile, the failure mode exhibits a ductile to brittle transition. We propose the concept of ice‐rock interface cohesive zone (ICZ), which consists of thin ice layer, thin rock layer, and their interface. The bonding strength of ICZ comes from the interlocking between ice and rock pores and the cohesion between ice and mineral grains, and thus being temperature and strain rate dependent. The temperature and strain rate dependency in mechanical behavior of ice‐sandwiched rock mass should originate from that of ice or the ICZ.