Abstract Swelling soils are problematic in terms of geotechnics, and they require mitigation actions in preliminary works. The most commonly used method to mitigate the damage caused by swelling soils is to stabilize the soil with chemical additives by using shallow mixing or column techniques. It is important to determine the most suitable additive material and the most appropriate technique when stabilizing swelling soils. The aim of this study is to investigate shallow mixing and column performances of various additives on the stabilization of swelling soils. Lime, fly ash and gypsum were chosen as the additives for this purpose. The study was conducted in the laboratory by creating the model of the land at the laboratory scale. Two different small scale models were designed for each additive, one for investigating their shallow mixing performances, and the other one for their column performances. A curing time of 4 months was considered for all of the models. At the end of the curing time, in order to determine the changes on the swelling behaviour of the soil, free swelling test was carried out on the specimens taken from the small scale model boxes. The results showed that the best improvement was achieved with lime for both techniques with reductions of 99.8% and 51.9% in the swelling percent of the soil when using the shallow mixing and column techniques, respectively. Gypsum, on the other hand, exhibited the lowest performance for both techniques by reducing the swelling percent of the soil by 65.42% with the shallow mixing technique and 25.3% with the column technique. Lastly, the shallow mixing technique showed 47.9%, 64.41% and 40.12% higher performances than the column technique for lime, fly ash and gypsum, respectively.

中文翻译：

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石灰、粉煤灰和石膏对膨胀土稳定的浅层混合和柱性能

摘要 膨胀土在岩土工程方面存在问题，需要在前期工作中采取缓解措施。减轻土壤膨胀造成的损害最常用的方法是使用化学添加剂通过浅混合或柱技术稳定土壤。在稳定膨胀土时，确定最合适的添加剂材料和最合适的技术很重要。本研究的目的是研究各种添加剂在稳定膨胀土方面的浅层混合和柱性能。为此选择石灰、粉煤灰和石膏作为添加剂。该研究是在实验室中通过创建实验室规模的土地模型来进行的。为每种添加剂设计了两种不同的小规模模型，一种用于研究它们的浅混合性能，另一种用于研究它们的柱性能。所有模型都考虑了 4 个月的固化时间。在养护时间结束时，为了确定土壤膨胀行为的变化，对取自小型模型箱的试样进行了自由膨胀试验。结果表明，石灰对这两种技术的改善效果最好，当使用浅层混合和柱技术时，土壤的膨胀百分比分别降低了 99.8% 和 51.9%。另一方面，石膏在两种技术中表现出最低的性能，浅混合技术将土壤的膨胀百分比降低了 65.42%，柱技术降低了 25.3%。最后，浅混合技术显示 47.9%，64。