Abstract
To analyze the effects of freeze-thaw cycles and confining pressure on the mechanical properties of red sandstone, through freeze-thaw cycles and triaxial compression tests, full stress-strain curves of different freeze-thaw cycles and different confining pressures were obtained. The degradation degree of red sandstone was quantitatively considered from different mechanical parameters of ultimate stress, elastic modulus, and Poisson’s ratio. Based on summarizing the characteristics of rock under freeze-thaw and load, the total damage variable of rock was determined by the reasonable measurement of freeze-thaw damage variable and load damage variable, and a damage constitutive model under freeze-thaw and load was established. The research showed that the freeze-thaw cycles aggravate the degree of rock damage deterioration, the rock stiffness and strength were reduced, and the characteristics of plastic deformation and ductile failure were more obvious. The confining pressure inhibited red sandstone internal damage, and with the increase of confining pressure, the stiffness and strength and the plastic characteristics were increased. In the overall trend, the mechanical parameters had different sensitivity to the degradation effect of freeze-thaw cycles and confining pressure. Regardless of the increase in the number of freeze-thaw cycles or confining pressure, the strain softening modulus tended to decrease gradually, and red sandstone plastic damage became more obvious after the stress peak. The total damage evolution path of red sandstone reflected the nonlinear influence of freeze-thaw and load on the total damage propagation. The research results provide theoretical support for the improvement of the technology of the effluent coal rock in Balasu Coal Mine.
Highlights
With the continuous development of economic globalization, the number and scale of cold regions engineering construction are gradually increasing. e freeze-thaw disaster will be the primary problem affecting cold regions construction. erefore, studying the damage characteristics and failure mechanism of rock under freezing and thawing has important theoretical and engineering significance to guarantee the safety of construction projects
Shaanxi red sandstone was selected for the study of freeze-thaw cycles and conventional triaxial compression test. e deterioration degree and the softening modulus were further obtained by the mechanical parameters. e stress–strain curves were obtained from the test data. e effects of freeze-thaw cycles and confining pressure on the damage characteristics of red sandstone were analyzed by the established constitutive relation
From the total damage variable expression of (12) and the damage constitutive model of (14), it can be seen that the determination of model parameters m and F0 was one of the key problems in model establishment
Summary
With the continuous development of economic globalization, the number and scale of cold regions engineering construction are gradually increasing. e freeze-thaw disaster will be the primary problem affecting cold regions construction. erefore, studying the damage characteristics and failure mechanism of rock under freezing and thawing has important theoretical and engineering significance to guarantee the safety of construction projects. Khanlari et al [11] selected five different types of sandstones to explore the effects of freeze-thaw cycles on the mechanical properties of rocks. Liu et al [13], Zhou et al [14], Wen et al [15] used red sandstone, granite porphyry, and limestone to conduct freeze-thaw cycles experiments and systematically studied the physical and mechanical properties of rocks. Yu et al [18] and Yu et al [19] studied the effects of freeze-thaw cycles on sandstone mechanical properties under triaxial compression conditions. E effects of freeze-thaw cycles and confining pressure on the damage characteristics of red sandstone were analyzed by the established constitutive relation Shaanxi red sandstone was selected for the study of freeze-thaw cycles and conventional triaxial compression test. e deterioration degree and the softening modulus were further obtained by the mechanical parameters. e stress–strain curves were obtained from the test data. e effects of freeze-thaw cycles and confining pressure on the damage characteristics of red sandstone were analyzed by the established constitutive relation
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