Study on Acoustic Emission and Damage Mechanical Properties of Freeze-Thaw Sandstone under Uniaxial Compression

Abstract

The damage strength of freeze-thaw rock provides an important reference for stability evaluations used during rock engineering in cold regions. In this paper, real-time acoustic emission tests of saturated sandstone are performed after various freeze-thaw cycles to study the uniaxial compressive strength and deformation characteristics of the resulting materials. The macro-meso damage evolution law of loaded sandstone is studied under the action of freeze-thaw cycles. The results show the following: (1) The saturated water absorption of sandstone increases, the peak strength and elastic modulus loss rates of sandstone increase linearly, and the frost resistance of the rock decreases with the number of freeze-thaw cycles. The sandstone failure mode gradually shifts from splitting failure to complex splitting shear failure of the failure surface. (2) If fewer than 10 freeze-thaw cycles are applied, the ring count signals at the compaction stage and after the peak strength is reached are extremely weak under a uniaxial compression load. With additional freeze-thaw cycles, damage inside the rock accumulates gradually, and the ring count signal appears during the rock compaction stage, fluctuates up and down, and continues until the peak strength is reached. When the compressive strength reaches its peak, the ring count intensity signal increases suddenly, and the frequency is high. After the strength reaches its peak, the acoustic emission signal shows that the rock sample still has some residual strength. As the number of freeze-thaw cycles increases, the cumulative ring count of sandstone gradually changes from the jumping stage to gradual growth. The acoustic emission characteristic parameters and ring count reflect damage to and expansion of freeze-thaw sandstone. (3) The cumulative extent of rock damage reaches the threshold value under loading and increases linearly until the rock is destroyed. When more freeze-thaw cycles are used, the time required for the rock to reach this threshold value is shorter, and the time required for sandstone damage is reduced gradually. These results provide a reference for the study of freeze-thaw damage and rock stability in cold regions.

Study on the Influence of Saturation on Freeze–Thaw Damage Characteristics of Sandstone

“…Due to the lack of free expansion space, the water in the sandstone pores produces a large frost-heaving force during the freezing process. Due to the different initial saturations, the formation and development degree of ice and the frost heave force of water are different under freezing conditions, and the degree of frost heave damage in the internal structure of rock samples is different [ 28 ]. When the saturation is low, the damage effect of water on rock is mainly chemical softening, and the frost-heaving effect of water is weak, so the damage effect of water on rock is limited.…”

Mechanical properties and acoustic emission characteristics of basalt fiber reinforced cemented silty sand subjected to freeze-thaw cycles

“…[31] through the accumulative ring-down count during unconfined compression test, showed that soil damage was characterized by ringing AE count by analyzing the variation relation between AE parameters and stress. Liang et al [32] manifested that the cumulative ring count of sandstone gradually changed from the jumping stage to gradual growth with repeated F-T cycles. The AE characteristic parameters and ring count reflected damage of F-T sandstone.…”

Mechanical properties and acoustic emission characteristics of mixed granite after different numbers of freeze‒thaw cycles

“…Furthermore, they also analyzed the AE spectra and concluded that the high amplitude-low frequency signals were best for predicting brittle fracture. Liang et al 30 conducted AE tests on saturated sandstone after freeze‒thaw cycles and found that the higher the number of freeze‒thaw cycles, the shorter the time it takes for the rock to reach the accumulated damage threshold. Wang et al 31 studied the deterioration properties of rocks with the help of AE technology and found that the AE event rate of sandstone gradually changed from the "V" type to the "U" type.…”