Experimental study and numerical modeling of the thermo-hydro-mechanical processes in soil freezing with different frost penetration directions

Abstract

This research work presents an experimental and numerical study of the coupled thermo-hydro-mechanical (THM) processes that occur during soil freezing. With focusing on the artificial ground freezing (AGF) technology, a new testing device is built, which considers a variety of AGF-related boundary conditions and different freezing directions. In the conducted experiments, a distinction is made between two thermal states: (1) The thermal transient state, which is associated with ice penetration, small deformations, and insignificant water suction. (2) The thermal (quasi-) steady state, which has a much longer duration and is associated with significant ice lens formation due to water suction. In the numerical modeling, a special focus is laid on the processes that occur during the thermal transient state. Besides, a demonstration of the micro-cryo-suction mechanism and its realization in the continuum model through a phenomenological retention-curve-like formulation is presented. This allows modeling the ice lens formation and the stiffness degradation observed in the experiments. Assuming a fully saturated soil as a biphasic porous material, a phase-change THM approach is applied in the numerical modeling. The governing equations are based on the continuum mechanical theory of porous media (TPM) extended by the phase-field modeling (PFM) approach. The model proceeds from a small-strain assumption, whereas the pore fluid can be found in liquid water or solid ice state with a unified kinematics treatment of both states. Comparisons with the experimental data demonstrate the ability and usefulness of the considered model in describing the freezing of saturated soils.

Cryosuction‐induced fracturing in multiphase porous materials: Numerical modeling and experimental validation

“…In analogy to [6], a two-dimensional, plane-strain numerical model of soil freezing and suction-induced crack is presented. The boundary conditions are shown in Fig.…”

“…1(left), where the soil sample consisting of lean clay is being cooled from the bottom while the top boundary is slightly heated to prevent freezing of the complete sample. The profiles for the cooling and heating temperatures (θ c and θ h ) as well as the thermo-mechanical and model parameters are adopted from [6]. The initial temperature of the soil sample is equal to ambient temperature θ a .…”

An algorithmic framework for computational estimation of soil freezing characteristic curves

“…To improve this framework, the more accurate constitutive models will be required for better coupling among mechanical, thermodynamic, and hydraulic parts. For example, the recent improvements in the phase‐field modeling of freezing soils can be leveraged to improve the prediction of movement of the freezing front 24,50 . At the same time, mechanical models that capture the heterogeneity and anisotropy of soils can be also useful for more accurate estimation of deformation.…”

Residual stresses in gas tungsten arc welding: a novel phase-field thermo-elastoplasticity modeling and parameter treatment framework

“…Unlike the sharp-interface approaches for describing the phase-change materials, the diffusive-interface approaches allow a much easier and stable FE implementation, whereas the finite thickness of the interface has its origin in the lower-scale phase-change description, see, e.g., [18,86]. In this regard, the PFM is applied in many research works to describe material phase change on the continuum scale, see, e.g., [101,102,[112][113][114]. In this case, the macroscopic interface thickness, which is dictated by the FE mesh size, could be orders of magnitude larger than the physical interface thickness.…”