Three- and four-point bending tests on artificial frozen soil samples at temperatures close to 0 °C

人工冻土式样在接近0 °C时的三点及四点弯曲试验

Cold Regions Science and Technology, Volume 134, February 2017, Pages 20-32

Yuko Yamamoto, Sarah M. Springman

Abstract：Degradation of alpine permafrost under global climate change has led to accelerated downslope creep, volume loss due to thawing and surface fissures in rock glaciers. This may lead to mass movements evolving through instabilities. It is hypothesised in this paper that the formation of cracks in the frozen body of a rock glacier can lead to triggering of such failures, and that analogue instrumented beam bending tests (with 3 and 4 supports/loading points) can be used to investigate fracture mechanics in frozen soil, with applications derivable for rock glaciers. Likely transitions between unpredictable brittle behaviour (through rapid crack formation, propagation or matrix destruction) and a more ductile response (dominated by micro-crack nucleation), can be established and quantified as a function of acoustic emission activity, deformation rate, solids-ice content and specimen temperature between 3.2 °C and ? 0.5 °C.

Computational thermo-hydro-mechanics for multiphase freezing and thawing porous media in the finite deformation range

基于计算水热力学的有限变形范围多相冻融多孔介质研究

Computer Methods in Applied Mechanics and Engineering, Volume 318, 1 May 2017, Pages 667-700

SeonHong Na, WaiChing Sun

Abstract：A stabilized thermo-hydro-mechanical (THM) finite element model is introduced to investigate the freeze–thaw action of frozen porous media in the finite deformation range. By applying the mixture theory, frozen soil is idealized as a composite consisting of three phases, i.e., solid grain, unfrozen water and ice crystal. A generalized hardening rule at finite strain is adopted to replicate how the elasto-plastic responses and critical state evolve under the influence of phase transitions and heat transfer. The enhanced particle interlocking and ice strengthening during the freezing processes and the thawing-induced consolidation at the geometrical nonlinear regimes are both replicated in numerical examples. The numerical issues due to lack of two-fold inf–sup condition and ill-conditioning of the system of equations are addressed. Numerical examples for engineering applications at cold region are analyzed via the proposed model to predict the impacts of changing climate on infrastructure at cold regions.