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| Discussion of the key issues within calculation of the fatigue damage of rocks subjected to freeze-thaw cycles |
| JIA Hailiang1，2，XIANG Wei2，SHEN Yanjun1，YANG Gengshe1 |
(1. School of Architecture and Civil Engineering，Xi?an University of Science and Technology，Xi?an，Shaanxi 710054，China；
2. Faculty of Engineering，China University of Geosciences，Wuhan，Hubei 430074，China) |
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Abstract The fatigue damage theory has been proven to be practical in estimating the damage of rock subjected to the repeated action of freezing and thawing. The application of the established frost fatigue model in the calculation of rock damage in the natural environments still faces several challenges，for instance，how to simplify the complicated natural freezing and thawing action，how to define the damage variable reasonably and how to calculate the frost damage of rock caused by the joint action of multiple mechanisms. In this paper，analysis is carried out corresponding to the above challenges. The results indicate that the diurnal and annual freeze-thaw cycle should be the research focus in the engineering activities，which could be classified into the low-cycle or high-cycle fatigue loads according to the saturation degree of rock and the flow rate of unfrozen water in rock respectively. The change of the porosity of rock reflects the underlying frost mechanism，and the damage variables are thus defined by the flaw area and residual strain. The damage generated by high-cycle loads is comparable to that generated by low-cycle loads according to the fatigue damage model. Moreover，the effect of the action sequence of low-cycle and high-cycle loads should be taken into account.
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2017, Vol. 36 
