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以贵州某高速公路沿线红黏土为研究对象,开展了干湿循环作用后红黏土的收缩特性试验研究,探讨了干湿循环次数和初始含水率对红黏土收缩性状的影响.试验结果表明:同一循环次数内,各试样的环向收缩率在6~8 h时达到稳定,而轴向线缩率则需更长的稳定时间;随着初始含水率增加,各试样的初始轴向线缩率减小,而初始环向收缩率增加;28%含水率试样具有相近的最终轴向变形和环向变形量,而34%含水率的试样环向变形量高于轴向变形量;初始含水率变化不大,但体缩率的变化率却明显不同,说明干湿循环过程使得土体内部结构变得不稳定,但颗粒间相互作用的本质未发生明显变化;干湿循环作用对重塑红黏土最优含水率位置的基本无影响,这说明其未能改变黏土集聚体内对结合水的最大吸附能力.通过压汞试验得到了不同干湿循环作用后试样的孔隙分布情况,随着干湿循环次数的增加小孔径尺寸和分布密度改变较小,而大孔径尺寸减小,分布密度也在减小.干湿循环作用对聚集体内孔径的影响大于对微聚体内孔隙影响,与所测得的宏观收缩规律相吻合.
Taking the red clay along an expressway in Guizhou as the research object, the shrinkage characteristics of red clay after the wetting and drying cycles were studied, and the effects of the number of wetting and drying cycles and the initial moisture content on the shrinkage of red clay were studied. The results show that: The cyclic shrinkage of each sample reached steady at 6 ~ 8 h, while the linear shrinkage required longer settling time. With the increase of initial moisture content, the initial axial line The shrinkage decreases and the initial circumferential shrinkage increases. The 28% moisture content samples have similar final axial deformation and circumferential deformation, while the circumferential deformation of the specimen with 34% moisture content is higher than the axial deformation ; The initial moisture content did not change much, but the rate of change of the shrinkage rate was significantly different, indicating that the internal structure of the soil became unstable due to the wet-dry cycle, but the nature of the interaction between the particles did not change significantly; The result showed that it did not change the maximum adsorption capacity of bound water in clay aggregates.The pore distribution of samples after different wetting and drying cycles was obtained by mercury intrusion test , With dry The smaller the pore size and distribution density change, the smaller the pore size and the smaller the distribution density. The effect of the wet-dry cycle on the aggregate pore size is greater than the effect on the micropore size, The macro-contraction law is consistent.