Abstract
The influence of low temperature on longitudinal wave velocity, uniaxial compression strength, tensile strength, peak strain, secant modulus, and acoustic emission characteristics of yellow sandstones was studied. The results show that the secant modulus increases with decreasing temperature when the axial strain is less than 0.6%, and a contrary influence performs for the subsequent stage due to the fracture of the pore ice. With the decrease in temperature, the uniaxial compression strength first increases and then remains at a relatively constant value of 34.44 MPa at about -40°C while the temperature ranges from -40°C to -70°C. The tensile strength shows an approximate linear increment as the temperature. The peak strain gradually increases with temperature in a three-stage piecewise linear form, and the increasing rate gradually decreases with the decreasing temperature. The phase transformation from liquid water at a temperature of 20°C to solid ice at a temperature of -3°C significantly increases the longitudinal wave velocity from 1.55 km/s to 3.36 km/s. When the temperature is lower than -10°C, the longitudinal wave velocity approximately increases linearly at a rate of 2.67 × 10 − 3 km / s · ° C − 1 with decreasing temperature.
Highlights
The mechanical properties of porous rock mass in a waterrich stratum at subzero temperature are of significance for the construction of highways, artificial freezing in a vertical shaft and metro, and storage and mining in cold regions such as the Tibet Plateau and Xinjiang district [1]
The experimental results denote that the strength, elastic modulus [3, 4], fracture toughness [5], and accumulative acoustic emission (AE) quantities [6] increase with decreasing temperature
The frozen temperature is within -20~20°C according to the standard requirements of the International Society of Rock Mechanics (ISRM), and the red sandstone is widely used with a porosity less than 10% [15]
Summary
The mechanical properties of porous rock mass in a waterrich stratum at subzero temperature are of significance for the construction of highways, artificial freezing in a vertical shaft and metro, and storage and mining in cold regions such as the Tibet Plateau and Xinjiang district [1]. The effects of cyclic loadingunloading [7], explosion [8], and chemical corrosion [9] decrease the strength, elastic modulus, and Poisson’s ratio of rock samples. A series of constitutive models have been proposed for frozen sandstone considering the loading ratio effect [7] Among these studies, the frozen temperature is within -20~20°C according to the standard requirements of the International Society of Rock Mechanics (ISRM), and the red sandstone is widely used with a porosity less than 10% [15]. The experiments on frozen saturated yellow sandstones with a porosity of 13.08% at a wide range of temperature -70~20°C are conducted to investigate the mechanical behaviors, including compression strength, tensile strength, deformation characteristics, and AE characteristics according to the uniaxial compression test. This study can provide some references for the construction and development of structures in high porosity rocks in very cold regions
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