微观结构特性是材料宏观现象的本质反映，利用X射线CT技术对地下工程三元乙丙橡胶防水卷材（EPDM）的微观结构进行研究，探讨该种材料的孔隙结构特性。使用NaCl溶液模拟地下水环境，借助显微CT设备对地下水环境下的三元乙丙橡胶防水卷材进行扫描，通过Matlab软件对所得图像进行处理，并引入孔隙等效直径概念，进行孔隙结构参数的计算和分析。结果表明： 所分析二维切片图像的大部分指标值较为接近；孔隙直径分布在0~60 μm，直径20 μm是孔隙个数分布规律变化的转折点；较大和较小直径的孔隙对其面积分布有重大贡献。结果证实，利用X射线CT技术可实现对地下工程防水材料微观孔隙特性的研究，为下一步防水材料损伤机制的研究提供方法基础。

Microstructural characteristics are the essential reflection of macro phenomenon. Microstructure of EthylenePropyleneDiene Monomer (EPDM) waterproof sheet applied to underground engineering is studied by using Xray CT technology; and the structural properties of pores in the material are discussed. The NaCl solution is prepared to simulate the groundwater environment. The EPDM waterproof sheet in groundwater environment is scanned with microCT; the acquired five images are processed with Matlab software; the concept of pore equivalent diameter is introduced and the relevant pore parameters are analyzed. The results show that: 1) There is only little difference among pore parameters of the five images. 2)The pore diameters are mainly in the range of 0-60 μm; and the diameter of 20 μm is the turning point of pore number distribution. 3) The large and small pores have a significant effect on pore area distribution. It is proved that the microCT is a feasible method for studying microscopic pore characteristics of waterproof material in underground engineering, so as to provide a basis for the farther research on damage mechanism of waterproof material.