张宏, 何灵灵, 刘海洋. 2019: 呼和浩特地区压实红黏土收缩开裂特性研究. 工程地质学报, 27(6): 1311-1319. DOI: 10.13544/j.cnki.jeg.2018-419
    引用本文: 张宏, 何灵灵, 刘海洋. 2019: 呼和浩特地区压实红黏土收缩开裂特性研究. 工程地质学报, 27(6): 1311-1319. DOI: 10.13544/j.cnki.jeg.2018-419
    ZHANG Hong, HE Lingling, LIU Haiyang. 2019: RESEARCH ON THE SHRINKAGE AND CRACKING CHARACTERISTICS OF COMPACTED RED CLAY IN HOHHOT. JOURNAL OF ENGINEERING GEOLOGY, 27(6): 1311-1319. DOI: 10.13544/j.cnki.jeg.2018-419
    Citation: ZHANG Hong, HE Lingling, LIU Haiyang. 2019: RESEARCH ON THE SHRINKAGE AND CRACKING CHARACTERISTICS OF COMPACTED RED CLAY IN HOHHOT. JOURNAL OF ENGINEERING GEOLOGY, 27(6): 1311-1319. DOI: 10.13544/j.cnki.jeg.2018-419

    呼和浩特地区压实红黏土收缩开裂特性研究

    RESEARCH ON THE SHRINKAGE AND CRACKING CHARACTERISTICS OF COMPACTED RED CLAY IN HOHHOT

    • 摘要: 红黏土在工程应用中易随环境温、湿度的变化产生收缩变形甚至开裂现象,从而诱发产生诸多工程问题。在工程应用中掌握红黏土的收缩与开裂性能,才能及时做出有效的防治措施。为此,以内蒙古地区典型红黏土为研究对象,在明确其击实特性的基础上,分析了红黏土在不同击实次数条件下的收缩特性并结合图像处理技术进一步阐释了压实红黏土裂缝形态的发展规律。试验结果表明:红黏土的最大干密度随着击实次数的增加呈线性增加,最佳含水率随着击实次数的增加呈线性减小的特征;红黏土失水率曲线随干燥时间呈指数规律变化,干燥初期,试样水分迅速蒸发呈线性变化,随着干燥时间的延续水分蒸发量逐渐减少,失水率曲线趋于稳定;随着击实次数的增加试样收缩率增大,收缩指标(径向线缩率、轴向线缩率以及体积收缩率)随干燥时间呈指数规律变化。红黏土收缩几何因子小于3,表明其轴向收缩大于径向收缩,红黏土收缩具有各向异性的特点;红黏土的裂缝特征参数(平均裂缝宽度、裂缝总长度、裂隙率)也随击实次数的增加而增大。试样击实次数的增加破坏了土体的黏粒结构,导致土体对结合水最大吸附能力减弱,降低了土体的持水能力,从而使土体的失水率、收缩率以及裂隙率增大。因此,在工程应用中增加击实次数以期改善红黏土的收缩与抗裂性是低效不经济的。

       

      Abstract: In engineering applications, red clay is prone to shrinkage, deformation and even cracking with the change of ambient temperature and humidity, which leads to many engineering problems. It is undoubted that only by mastering the shrinkage and cracking properties of red clay can effective preventive measures be taken in time. For this reason, this paper takes the typical red clay in Inner Mongolia as the research object. On the basis of the compaction characteristics, the shrinkage characteristics of red clay under different compaction times are analyzed subsequently. The development pattern of fracture morphology of the compacted red clays is further explained by means of image processing technology. The results show that the maximum dry density of red clay increases linearly with the increase of compaction times, while the optimum moisture content decreases linearly with the increase of compaction times. At the same time, the water loss rate varies exponentially with drying time. In the early stage of drying, the water evaporation of the sample changes linearly. With the continuation of drying time, the water evaporation decreases gradually, and the water loss rate curve tends to be stable. Furthermore, with the increase of compaction times, the radial, axial and volume shrinkage changes exponentially with drying time. The shrinkage geometric factor of the red clay is less than 3, which indicates that axial shrinkage is larger than that of radial shrinkage. The shrinkage of the red clay is anisotropic. Increase in the sample compaction times can destroy the clay particles. The average crack width, total crack length and crack percentage of the red clay are increased as well. Simultaneously, the maximum adsorptive capacity of the clay to bound water is weakened. The water holding capacity is reduced, the water loss rate, shrinkage rate and crack percentage increase correspondingly. Therefore, it is inefficient and uneconomical to increase the number of compaction times in engineering application to improve the shrinkage and crack resistance of red clay.

       

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