吴盈盈, 刘旭阳, 王振亭. 干燥致密土壤在沙粒流冲击下的磨蚀规律[J]. 农业工程学报, 2022, 38(8): 315-320. DOI: 10.11975/j.issn.1002-6819.2022.08.036
    引用本文: 吴盈盈, 刘旭阳, 王振亭. 干燥致密土壤在沙粒流冲击下的磨蚀规律[J]. 农业工程学报, 2022, 38(8): 315-320. DOI: 10.11975/j.issn.1002-6819.2022.08.036
    Wu Yingying, Liu Xuyang, Wang Zhenting. Abrasion law of dry and dense soil under the bombardment of sand grain flows[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2022, 38(8): 315-320. DOI: 10.11975/j.issn.1002-6819.2022.08.036
    Citation: Wu Yingying, Liu Xuyang, Wang Zhenting. Abrasion law of dry and dense soil under the bombardment of sand grain flows[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2022, 38(8): 315-320. DOI: 10.11975/j.issn.1002-6819.2022.08.036

    干燥致密土壤在沙粒流冲击下的磨蚀规律

    Abrasion law of dry and dense soil under the bombardment of sand grain flows

    • 摘要: 在土壤风蚀过程中,跃移颗粒对表土的冲击磨蚀是公认的一种重要起尘机制。磨蚀体现了跃移沙与土壤相互作用,受沙粒跃移运动参数和土壤力学性质共同控制。然而,现有风蚀模型尚未充分考虑土壤力学性质的地位与作用,缺少磨蚀速率计算公式,亟需从固体力学角度探讨土壤磨蚀规律。该研究借鉴岩石磨蚀模型,针对含水率小于1.5%、体密度大于1.60×103 kg/m3的干燥致密土壤,提出了代表单位时间内的碰撞次数、土壤抗压强度和杨氏模量、入射沙粒动能和密度等综合效应的磨蚀变量;通过标准压缩试验测得黏土、砂土、壤土、砂质黏土、壤质黏土共5种人工均质土壤的抗压强度和杨氏模量的范围分别为0.823~4.092 MPa和0.043~0.149 GPa;利用自行设计的冲击磨蚀试验得到了干燥致密土壤在沙漠沙颗粒流冲击作用下的磨蚀规律,即磨蚀速率是磨蚀变量的线性函数,其斜率与截距分别为3.27×104和-0.027 kg/s。研究结果有助于恰当描述风蚀模型中的土壤力学性质、准确计算风蚀速率,进而服务于农田防护和水土保持工程,并为中国西北干旱区天然地貌和人工建筑风蚀现象的研究提供理论依据与数据支撑。

       

      Abstract: Abstract: Saltation bombardment is a well-recognized dominant dust emission mechanism in the dynamic of soil erosion by wind. Since the abrasion can be caused by the interaction of saltating grains and soil, this specific process of particle transport can be jointly controlled by the saltation parameters of sand grains and the mechanical properties of soil. However, many current models of wind erosion cannot fully consider the function of soil, although some new concepts were suggested previously, such as rupture modulus, binding energy, and surface strength. Particularly, it is still lacking in the soil mechanical properties in wind erosion. Fortunately, the theoretical models of rock abrasion were greatly improved in classical mechanics in recent years. Some types of soil can also share the common characteristics with rocks, such as elasticity and failure behaviors. Therefore, it is a high demand to develop the new abrasion models for soil or rocks. In the presented study, a robust abrasion model of soil was proposed to determine the abrasion variable, considering the comprehensive effects of the impact number per unit time, the yield stress and Young's modulus of soil, the kinetic energy and density of the impacting sand grains. A series of experiments were conducted to examine the interaction between abrasion rate and abrasion variable. Firstly, five types of cylindrical specimens were prepared to cover the man-made, uniform, dry and dense soil, i.e. clay, sand, loam, sandy clay, and loamy clay. Secondly, the compressive strength and Young's modulus of the soil were measured using a standard universal testing machine. Thirdly, seven abrasion experiments were performed on each soil type. Among them, a newly developed sandblasting gun was also utilized under different impact speeds of natural desert sand grains with a nearly uniform sieve size. An analytical balance was used to measure the mean abrasion rates or mass loss per unit time. Meanwhile, the abrasion variable was calculated after measurement. The results revealed that the compressive strength and Young's modulus were 0.823-4.092 MPa and 0.043-0.149 GPa, respectively. There was a linear correlation in the abrasion rate of dry and dense soil, where the slope and intercept were 3.27×104 and -0.027 kg/s, respectively, when abrasion variable is less than 3.0×10-2 g/s. The theoretical model was agreed with the experimental data, because the uniform, dry and dense soil fully meets the assumption of perfect elasticity, and more importantly, the soils in this study behave as the brittle materials, similar to impact targets in rock abrasion models. The abrasion area per impact was much smaller than the target size in the Hertz contact model. The non-positive intercept in the rate-variable relation indicated that the abrasion occurred, once the abrasion variable was larger than the threshold. In addition, the detailed abrasion expressions vary in the types of soil, in terms of the compressive strength, Young's modulus, slope, and intercept. The finding can provide the data support for the wind erosion of various natural features and artificial structures, such as farmlands, dried lake bases, ancient riverbeds, yardangs, and ancient city ruins, which are widely distributed in the arid region of Northwest China.

       

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