Investigating Mechanical Behaviors of Rocks Under Freeze-Thaw Cycles Using Discrete Element Method

In this study, we adopt the Discrete Element Method (DEM) to evaluate the influence of Freeze-Thaw Cycles (FTCs) action on the mechanical properties of rock. To overcome the intrinsic porosity limitation of DEM model and better represent the saturated rock sample, we develop an algorithm to include particles of smaller and varying sizes into rock pores. The ice-water phase change and the resulting accumulation of residual strain are considered by developing an elastoplastic parallel bond model in PFC2D. The rationality of this model is first validated by comparing numerical results with published experimental data. Numerical results highlight the FTCs deterioration of the uniaxial compressive strength (UCS) and Young's modulus of rock specimens. We establish exponential correlations between the FTCs number and the rock's mechanical property, with the trends consistent with experimental observations. Inter-particle contact damage also reflects the formation and distribution of micro-fractures in rock specimens under freeze-thaw cyclic treatments. Based on the elastoplastic parallel bond model, we explore the influences of porosity and initial UCS on decay constant which reflects the freeze-thaw resistance of rock. It is found that decay constants of UCS and Young's modulus decrease with the increase of porosity. While the decay of UCS decreases with the increase of initial UCS, which means the sample of larger initial UCS is harder to be deteriorated by FTCs. This study provides new insights into the rock degradation process under changing climate and may contribute to the future design and assessment of climate-resilient infrastructure.

Automated summary

This study evaluates the influence of Freeze-Thaw Cycles (FTCs) on the mechanical properties of rock using the Discrete Element Method (DEM). A new algorithm is developed to better represent the saturated rock samples in the DEM model. The results show that FTCs deteriorate the uniaxial compressive strength (UCS) and Young's modulus of rock specimens. The study also explores the effects of porosity and initial UCS on the decay constant, which reflects the freeze-thaw resistance of rock.