Characterization of Thermal-Hydraulic Coupling Behavior for Moraine Soil With Ice Inclusions in a Warming Environment

A warming environment is promoting the thawing process in ice-rich moraine soils in cold alpine regions, thereby accelerating the formation/development of geohazards in these regions. The mechanism of these geohazards is closely related to the thermal-hydraulic (TH) coupling behavior of moraine soils, which has rarely been investigated. Here, we conducted a series of bench-scale TH coupling simulations of moraine soils with ice inclusions in a warming environment. The numerical model was conceptualized from a field survey on the Qinghai-Tibet Plateau, which consists of a porous medium embedded with multilayer ice cubes with warmer water continuously flowing through it. A TH coupling framework considering ice-water phase change was established to implement this coupled simulation with different initial ice contents and hydraulic gradients. The simulated results showed phased and nonlinear evolutionary features of temperature, ice content, and permeability for the moraine soil system. Further analyses showed that these complex evolutionary features can be reproduced by empirical formulas, with concise expressions following dimensional consistency and some coefficients having potential physical meanings. The discriminant models of two equilibrium states were finally developed to predict the critical times of structure stabilization and thermal equilibrium of the moraine soil system. This study presents the complex evolution of TH coupling properties of moraine soils, and simultaneously demonstrates that these properties can be predicted and characterized. Due to large-scale and multistage glacier evolution, substantial moraine soils have accumulated in cold alpine regions. These moraine soils include abundant buried ice in various configurations formed during glacial evolution, and the thawing of this buried ice is accelerating the development of geohazards in these regions. The initiation and evolution of these geohazards are largely controlled by heat transport and groundwater flow induced by ice-water phase change in moraine soils, but these coupling processes are poorly understood and poorly characterized. Here, we numerically investigated the thermal-hydraulic (TH) coupling behaviors of moraine soils with ice inclusions in a warming environment. The simulated results revealed phased and nonlinear evolutionary features of the moraine soil system, with respect to heat transport, pore structure, and hydraulic conductivity. We demonstrated that these complex evolutionary features can be well characterized by empirical formulas, and their equilibrium states can be predicted based on the initial ice content and applied hydraulic gradient. These findings and results deepen our understanding of TH coupling behavior for moraine soils with ice inclusions, and serve as a basis for characterizing evolutionary processes of geohazards related to moraine soils in cold alpine regions under climate warming. Fully coupled thermal-hydraulic simulations considering phase change were conducted for moraine soils with separate ice inclusionsEvolution of heat transport, ice content, and hydraulic conductivity of moraine soil was quantitatively characterizedEquilibrium-state discrimination models were developed to predict structure stabilization and thermal equilibrium of the moraine soil system