基于CT图像直方图技术的冻结岩石未冻水含量及损伤特性分析

未冻水含量是影响岩石低温冻结过程中热力学性质的重要因素, 是冻土科学研究中的重要问题. 采用CT无损识别技术进行不同温度梯度下岩石CT扫描实验, 获得了20℃、-2℃、-5℃、-10℃、-20℃、-30℃下岩石的CT扫描图像. 以数字图像处理理论为依据, 运用CT图像直方图技术进行不同温度梯度下冻结岩石CT图像解析, 完成了冻结岩石未冻水含量及损伤信息的定量分析. 研究结果表明: -2~-5℃是岩石内未冻水含量急剧减小的温度区间; 当温度降到-10℃时, 岩石内未冻水全部冻结成冰. 根据CT数直方图峰形形状可判别低温环境下冻结岩石的损伤大小及分布均匀性. 论文所提出的冻结岩石CT图像直方图技术为定量分析不同温度梯度下冻结岩石未冻水含量、损伤扩展随温度的变化规律提供了新的方法和思路.

Analysis of unfrozen water content and damage characteristics based on histogram technique of CT images

Unfrozen water is an important factor in thermodynamic property of frozen rock during freezing under low temperature,which is the key and difficult problem in the research of frozen rock.By CT identification tech-nology,CT scanning experiment of frozen rock was carried out under 20℃,-2 ℃,-5 ℃,-10℃,-20℃and -30 ℃.CT scanning images of frozen rock at various temperatures were obtained.Based on digital image processing theory and method,according to mesoscopic physical information contained in CT images of frozen rock,histogram technique of CT images was achieved to analyze CT images of frozen rock under different ther-mal gradients.By the method proposed in this paper the variation of unfrozen water and damage were analyzed quantitatively.It is found that the temperature range of unfrozen water decreasing significantly is from -2 to-5 ℃.There is only a few unfrozen water in frozen rock when the temperature ranges from -5 to -10 ℃. When the temperature lower than -10 ℃,there is no unfrozen water.The peak shape of CT value histogram can intuitively display the damage degree of frozen rock.The histogram technology of frozen rock provides a new method for quantitatively analyzing the damage evolution process of frozen rock under different thermal gradients.