膨胀岩是一种特殊软岩，在干湿循环作用下容易崩解泥化。针对延吉膨胀岩，开展干湿循环作用下膨胀岩浸水崩解试验，研究其粒径变化规律。根据干湿循环后粒径分布，引入标准基础熵表征膨胀岩崩解特性，并与崩解比进行类比分析。研究结果表明：各粒组含量在前3次干湿循环中变化较大，第3次干湿循环后逐渐趋于稳定；随着干湿循环次数的增加，粗颗粒含量逐渐减少，细颗粒含量增加，土颗粒大小经历了由均匀到不均匀，再到均匀的过程；标准基础熵与崩解比存在明显的线性负相关关系，标准基础熵随着崩解比的增大而减小，表明利用标准基础熵表征颗粒分布规律是合理可行的；随着干循环次数的增加，标准基础熵先减小，后逐渐稳定，与级配曲线及其衍生指标变化规律相同，再次验证该方法的可行性和适用性，为膨胀岩的崩解破碎分析提供一种新的量化指标；膨胀岩路堑边坡开挖以后，应及时采取防水保湿措施，防止发生崩解泥化现象。

Swelling mudstone is one type of special soft rock with a feature of collapsing under drying and wetting cycles. Water immersion tests were conducted in laboratory to examine disintegration behavior of Yanji swelling mudstone under drying and wetting cycles. On the basis of grain size distributions, relative base entropy is proposed to measure the disintegration behavior, and is compared with disintegration ratio. The results show that the groups of different grain sizes change greatly at the initial 3 cycles, and then tend to be stable. With the increase of the number of wetting and drying cycles, the coarse particle content gradually decreases, the fine particle content increases. The particle size changes from the homogeneous to the heterogeneous state, then back to the homogeneous state. There is a significant negative linear relationship between relative base entropy and disintegration ratio. The relative base entropy decreases with the increase of disintegration ratio, implying reasonable and feasible measurement of the grain size distributions using proposed relative base entropy method. The relative base entropy decreases gradually with the increase of the number of drying and wetting cycles, and finally tends to be stable, which agrees well with the changes in the grain size distribution and its derived indexes. Hence, the feasibility and applicability of the proposed approach are verified again, and the relative base entropy can be a new useful index for the quantitative analysis of the disintegration of swelling mudstone. After the excavation of cutting slopes, waterproofing and moisturizing measures should be taken in time to prevent the disintegration and argillitization of swelling mudstone.