Abstract
Abstract The preexistence of the geological discontinuities in cold regions is susceptible to freeze-thaw weathering and rock instability, and even the occurrence of geological hazards is strongly impacted by the discontinuities. Knowledge of how natural fracture affects the rock field deformation is crucial to rock stability prediction. This work is aimed at revealing the influences of freeze-thaw on failure process for pyrite-filled marble obtained from an open pit slope. All the tested marbles were selected to roughly have the same initial pyrite band; the full-field displacement and the progressive failure behaviors under uniaxial compression were qualitatively and quantitatively analyzed using 3D digital image correlation (3D DIC) technique. The testing results show that the previous freeze-thaw action weakens the cementation between the rock matrix and pyrite band; the peak stress and strain are obviously impacted by the freeze-thaw treatment. In addition, the stimulation of pyrite bands influences the displacement development and high strain concentration pattern. The stimulation of pyrite band results in the formation of strain concentration zone, and shear sliding occurs until rock failure. Moreover, it is found that the stimulation of pyrite band and its localized strain takes place progressively and develops fast for marble exposed to higher freeze-thaw treatment. It is suggested that the field deformation development depends on the stimulation of the pyrite bands.
Highlights
Rock mass in cold regions suffers from repeated freeze-thaw weathering, and its structural deterioration would lead to the occurrence of a series of geological hazards, such as collapses, landsides, and avalanche [1,2,3]
Three-dimensional digital image correlation (3D DIC) technique was employed to investigate the influence of freeze-thaw on field deformation of pyrite-filled marble under uniaxial compression
The full-field displacement and strain patterns in different loading stages of rock failure were successfully captured during the whole process
Summary
Rock mass in cold regions suffers from repeated freeze-thaw weathering, and its structural deterioration would lead to the occurrence of a series of geological hazards, such as collapses, landsides, and avalanche [1,2,3]. What is more serious is that under freeze-thaw conditions, 9% volume expansion will occur when water turns into ice [8,9,10,11,12], and frost heave pressure will be generated within the existing cracks or discontinuities. Plenty of attempts have performed by laboratory testing to reveal the impact of freeze-thaw action on rock structural degradation and the associated geomechanical behaviors with respect to porosity, deformation, strength, elastic modulus, velocities, failure mode, etc. As a kind of discontinuous material, the effects of water-ice phase transformation on natural fractures and the frost heaving cracking are the primary reason resulting in the failure of rock structure. A coupled thermo-hydro-mechanical model has been developed by Huang et al [17], and the influences of temperature and pore water-ice pressure on frost heaving
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