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广州红黏土在地铁建设中极易软化、崩解,对城市地铁工程的安全构成威胁.通过室内物理力学试验、X射线衍射试验、扫描电镜试验,得到了广州饱和红黏土的基本物理性质,以及该类红黏土体的矿物成分、微观结构特点.基于试验结果,提出了一种土体微观模型,分析了微观结构对该类红黏土物理性质的影响,并运用此模型求得了该类饱和红黏土的孔隙比.结果表明:该类红黏土的饱和含水量为62%,自由膨胀率达到40%,黏性矿物所占比率很大,片状和扁平状黏土颗粒相互聚集形成的层状微集聚体是组成红黏土微观结构的主要结构单元体,运用微观结构参数求得的孔隙比为1.62～1.80,与宏观试验结果相一致.
Guangzhou red clay can easily soften and disintegrate in the subway construction, which poses a threat to the safety of urban metro project. The physical properties of Guangzhou saturated red clay are obtained through physical and mechanical tests, X-ray diffraction and SEM. Based on the test results, a kind of soil microcosmic model was proposed to analyze the effect of microstructure on the physical properties of this type of red clay. The saturation red The results show that the saturated water content of this type of clay is 62%, the free expansion rate is 40%, and the proportion of viscous minerals is very large. The layered and micro Aggregates constitute the main structural unit of microstructure of red clay. The porosity ratio obtained from the microstructure parameters is 1.62 ~ 1.80, which is consistent with the macro-test results.