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首页> 外文期刊>Bulletin of engineering geology and the environment >Shear strength and mesoscopic character of undisturbed loess with sodium sulfate after dry-wet cycling
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Shear strength and mesoscopic character of undisturbed loess with sodium sulfate after dry-wet cycling

机译：干湿循环后原状黄土硫酸钠的抗剪强度和介观特性

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摘要

The deterioration of shear strength of loess under dry-wet cycling is one of the serious threats to natural and artificial slopes in loess terrains in China, especially when soluble salts are involved. Three types of salt weathering spalling were noted from field survey, i.e., strip-, flake-, and concave-shaped spalling. These are closely correlated with the migration of both water and salt as well as the deterioration of shear strength of the soil. A novel saline infiltration method was proposed to prepare undisturbed saline loess specimens by slowly infiltrating sodium sulfate solution into undisturbed loess through a perforated film and medium dense sponge. Conventional triaxial test results prove that the stress-strain curves are all strain hardening. Both the cohesion and internal friction angle decrease after dry-wet cycling, but the magnitude of reduction gradually decreases until a stable value is reached, manifesting as an exponential decay. The two indexes approximately attenuate linearly at higher salt contents. Moreover, the cohesion-based damage ratio was selected to quantitatively estimate the damage caused by dry-wet cycles and salt weathering, respectively. The damage ratio due to dry-wet cycling is higher than that by salt weathering. As dry-wet cycling proceeds, the ratio of dry-wet to salt weathering-induced damage initially increases followed by a decrease, which is approximately parabolic. The dry-wet-based damage ratio reduces at higher salt contents while the proportion by salt weathering grows. By quantifying the apparent surface cracks, the crack ratio grows after more cycles or at higher salt contents. A growing fractal dimension can also be observed. Based on the computed tomography (CT), a damage variable was determined for mesoscopic cracks. Easily, it can be noticed that the changes in crack ratio are synchronized with the attenuation of cohesion of loess as well as the mean CT value (ME).
机译：干湿循环下黄土抗剪强度的下降是对中国黄土地形中自然和人工斜坡的严重威胁之一，特别是当涉及可溶性盐时。现场调查发现盐类风化剥落有3种类型，即条状，片状和凹状剥落。这些与水和盐的迁移以及土壤抗剪强度的下降密切相关。提出了一种新的盐水渗透方法，即通过穿孔的薄膜和中等密度的海绵将硫酸钠溶液缓慢渗透到未受干扰的黄土中，以制备未受干扰的盐水黄土标本。常规的三轴试验结果证明，应力-应变曲线都是应变硬化。干湿循环后，内聚角和内摩擦角均减小，但减小的幅度逐渐减小，直到达到稳定值为止，表现为指数衰减。这两个指数在较高的盐含量下近似线性衰减。此外，选择基于内聚力的破坏比率来定量地估计干湿循环和盐分风化造成的破坏。干湿循环造成的破坏率高于盐风化。随着干湿循环的进行，干湿与盐风化引起的损害之比最初会增加，然后减少，这近似于抛物线。盐含量较高时，基于干湿的破坏率会降低，而盐风化的破坏率会增加。通过量化表观表面裂纹，裂纹率在更多的循环之后或在更高的盐含量下会增加。分形维数也在增加。基于计算机断层扫描（CT），确定介观裂纹的损伤变量。容易注意到，裂纹率的变化与黄土凝聚力的衰减以及平均CT值（ME）同步。

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    Xian Univ Architecture & Technol Sch Civil Engn Xian 710055 Shaanxi Peoples R China|Xian Univ Architecture & Technol Shaanxi Key Lab Geotech & Underground Space Engn Xian 710055 Shaanxi Peoples R China;

    Xian Univ Architecture & Technol Sch Civil Engn Xian 710055 Shaanxi Peoples R China;

    Xian Univ Technol Inst Geotech Engn Xian 710048 Shaanxi Peoples R China;

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  • 关键词

    Loess; Dry-wet; Shear strength; Fractal dimension; Damage variable;

    机译：黄土;干湿;剪切强度;分形维数伤害变量;

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