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冻结岩石中冰含量对其热力学及损伤特性有重要影响,研究岩石冻结过程中冰含量随温度的变化规律可以为冻结岩石工程的安全稳定性评价提供科学依据。运用CT识别技术,进行不同温度梯度下冻结岩石的CT扫描实验,获得20℃、-2℃、-5℃、-10℃、-20℃、-30℃下岩石的CT扫描图像,实现了冻结岩石CT图像的伪彩色增强和直方图分析,完成了冻结岩石冰含量及损伤信息的数字表述,对冰含量随温度的变化规律进行定量分析。依据损伤力学理论,定义以冰含量表示的冻结损伤变量,探讨了未冻水含量和温度梯度对冻结岩石损伤特性的影响规律。研究结果表明:(-2℃,-5℃)是水冰剧烈相变的温度区间,冻结损伤演化起始和急剧增大阶段;(-5℃,-10℃)是冻结损伤发展阶段;(-20℃,-30℃)是冻结损伤趋于稳定的温度区间。所定义的冻结损伤变量能够描述温度降低过程中岩石损伤的演化过程,基于冻结岩石CT图像伪彩色增强的冻结岩石损伤演化的定量分析为冻结岩石工程的稳定性研究提供了新的思路和方法。
The ice content in the frozen rock has an important influence on the thermodynamic and damage properties. Studying the variation law of the ice content with the temperature during the rock freezing process can provide a scientific basis for the safety and stability evaluation of the frozen rock project. CT scanning experiments of frozen rocks under different temperature gradients were carried out by using CT identification technology to obtain CT images of rocks at 20 ° C, -2 ° C, -5 ° C, -10 ° C, -20 ° C and -30 ° C to achieve a freeze Pseudo color enhancement and histogram analysis of rock CT images were completed, and the digital expression of ice content and damage information of frozen rock was completed. Quantitative analysis of ice content with temperature was carried out. Based on the theory of damage mechanics, the freezing damage variables are defined as ice content, and the influence of unfrozen water content and temperature gradient on the damage characteristics of frozen rock is discussed. The results show that: (- 2 ℃, -5 ℃) is the temperature range of severe phase transition of water ice, and the onset and rapid increase of freeze damage start up; (-5 ℃, -10 ℃) is the development stage of freeze damage; -20 ° C, -30 ° C) is a temperature range where freezing damage tends to be stable. The defined damage variable can describe the evolution of rock damage during the temperature decrease. Quantitative analysis of damage evolution based on pseudo-color enhancement of frozen rock CT images provides a new idea and method for studying the stability of frozen rock engineering.