Fig 1.
(a) 48 sandstone samples used in this experiment, (b) ZYB-II vacuum pressurized water saturation device, (c)static strain gauge, (d) diagram of experimental system, including uniaxial compression testing system, AE system and high-speed camera.
Fig 2.
Stress-strain curves of freeze-thaw cycling sandstone under different loading rates.
The sandstone samples subjected to 0, 30, 50, and 70 freeze-thaw cycles were labeled as FT0, FT30, FT50, and FT70, respectively. (a) 0.05 mm/min, (b) 0.10 mm/min, (c) 0.15 mm/min, (d) 0.20 mm/min.
Fig 3.
Stress-strain curves of four groups of typical sandstone samples.
Table 1.
Detailed table of sandstones mechanical parameters change.
Fig 4.
Variation law of UCS.
Fig 5.
Crack characteristics of sandstone subjected to 0 freeze-thaw cycles at loading rate of 0.05mm/min. (a) tp-49.19s, (b) tp-12.03s, (c) tp, (d) tp
+ 19.13s.
Fig 6.
Crack characteristics of sandstone subjected to 70 freeze-thaw cycles at a loading rate of 0.05 mm/min. (a) tp-100.01s, (b) tp-19.89s, (c) tp, (d) tp
+ 33.15s.
Fig 7.
Crack characteristics of sandstone subjected to 0 freeze-thaw cycles at loading rate of 0.20 mm/min. (a)tp-29.84s, (b) tp-5.32s, (c) tp-3.55, (d) tp.
Fig 8.
Crack characteristics of sandstone subjected to 70 freeze-thaw cycles at a loading rate of 0.20mm/min. (a) tp-107.3s, (b) tp-15.26s, (c) tp, (d) tp
+ 30.23s.
Fig 9.
Variation law of RA and AF in sandstone with different freeze-thaw cycles under a loading rate of 0.05mm/min.
(a) FT0, (b) FT30, (c) FT50, (d) FT70. ‘T’ refers to the tensile crack area, and ‘S’ refers to the shear crack area. The blue areas signify sparse distribution of scattered points, while the red areas indicate a dense concentration. The two curves shown respectively illustrate the cumulative count of tensile and shear cracks as a function of time.
Fig 10.
Variation law of RA and AF in sandstone with different freeze-thaw cycles under a loading rate of 0.20mm/min.
(a) FT0, (b) FT30, (c) FT50, (d) FT70. The detailed illumination of Fig.10 is the same as that of Fig.9.
Fig 11.
Variation law of AE events rate of sandstone under different freeze-thaw cycles at a loading rate of 0.05 mm/min.
(a) FT0, (b) FT30, (c) FT50, (d) FT70. The black circle in the figure indicates the phenomenon of low AE events rate missing.
Fig 12.
Variation law of AE events rate of sandstone under different freeze-thaw cycles at a loading rate of 0.05 mm/min.
(a) FT0, (b) FT30, (c) FT50, (d) FT70. The black circle in the figure indicates the phenomenon of low AE events rate missing.
Fig 13.
Variation law of AE b-value of sandstone under different freeze-thaw cycles at a loading rate of 0.05 mm/min.
(a) FT0, (b) FT30, (c) FT50, (d) FT70.
Fig 14.
Variation law of AE b-value of sandstone under different freeze-thaw cycles at a loading rate of 0.20mm/min.
(a) FT0, (b) FT30, (c) FT50, (d) FT70.
Fig 15.
Variation law of attenuation constant of sandstone with different loading rates.
Fig 16.
Comparison of UCS tests and models of sandstone under different loading rates and freeze-thaw cycles.