Abstract
The deformation rules and failure types of rock fatigue damage at different temperatures are quite different, and existing constitutive theory cannot describe them quantitatively. A novel rock fatigue damage model considering the effects of temperature was presented based on phenomenology. In this model, the residual strain method was used to define the fatigue damage, and the Harris attenuation function was introduced to characterize the cyclic damage evolution. The proposed model has considered the influence of the initial damage and temperature, and the model parameters can be easily calculated. The accuracy of the model was verified by comparing the calculated values of cyclic upper strain and fatigue life with previous test results. The physical significance of the model parameters shows that parameter a is related to fatigue stress ratio and lithology, while parameter b is related to temperature. The study has some reference values for the fatigue damage model of rock considering the influence of temperature.
Highlights
Song et al [22] and Zhao et al [23] carried out fatigue tests on salt rock and granite under real-time temperature, respectively. e test results show that temperature causes fatigue damage and affects the deformability of rock
To solve the above limits, a new fatigue damage model considering the influence of temperature was established by introducing Harris attenuation function. e initial damage is dependent on the damage model; the fatigue life can be predicted at the beginning of the cycle. e applicability of the model was verified by comparing with previous experimental data. is paper is of great significance to understand the fatigue damage law of rock under real-time temperature
Fatigue life prediction equation was built based on the fatigue damage model and uniaxial compression strain of rock
Summary
Deep rock engineering is a hot topic in recent years, and there is increasing interest in investigating the characteristics and mechanisms of deep rock failure [1,2,3,4]. e surrounding rocks of deep-buried compressed air energy storage (CAES) and tunnel engineering are always in a state of high ground temperature (as shown in Figure 1). is is due to the fact that the ground temperature will increase with the buried depth (the ground temperature gradient is generally 30∼50°C/km [5]), especially for nuclear waste disposal projects, and the temperature of the rock could even reach thousands of degrees. e mechanical properties of various types of rocks such as granite [6], sandstone [7], marble [8], and salt rock [9] have been studied under real-time temperature. e results show that the strength and elastic modulus of rocks decrease with the increase of temperature. E mechanical properties of various types of rocks such as granite [6], sandstone [7], marble [8], and salt rock [9] have been studied under real-time temperature. The cycle numbers are limited and the cyclic load is applied after the applied temperature in the aforementioned works, which is different from the rock fatigue damage at real-time temperature. The damage models used by Xie et al [24] and Liu et al [26] require input parameters like unloading elastic modulus and residual plastic deformation in each cyclic stress-strain curve, or the energy consumed, while the model developed by Xiao et al [27] needs the position of x0. To solve the above limits, a new fatigue damage model considering the influence of temperature was established by introducing Harris attenuation function. e initial damage is dependent on the damage model; the fatigue life can be predicted at the beginning of the cycle. e applicability of the model was verified by comparing with previous experimental data. is paper is of great significance to understand the fatigue damage law of rock under real-time temperature
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