In the present study, an experimental investigation was conducted to examine the effect of the size of additives on the improvement of collapsible soils. For this purpose, three collapsible soils with severe collapse potential were selected from Varamin Plain, Iran. The selected soils were then treated in the laboratory by the addition of alumina materials in two sizes of 70 nm (nano-alumina) and 685 nm (micro-alumina) and in different contents to improve their mechanical properties. Soil properties including collapse potential, uniaxial compressive strength, compressive modulus of elasticity, direct tensile strength, and tensile modulus of elasticity were selected as the target parameters for the improvement. These parameters were measured and determined before and after the treatment and the behaviors of treated soils were studied in both compression and tension states. The obtained results indicated that the nanometric and micrometric additives have diverse effects on the performance of the treated soil under compression and tension conditions.

中文翻译：

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研究添加剂的尺寸对改善湿陷性土壤的拉伸和压缩强度及变形特性的影响

在本研究中，进行了一项实验研究，以检查添加剂尺寸对改善可塌陷土壤的影响。为此，从伊朗瓦拉明平原（Varamin Plain）选择了三种具有严重崩塌潜力的可塌陷土壤。然后在实验室中通过添加两种尺寸为70 nm（纳米氧化铝）和685 nm（微氧化铝）且含量不同的氧化铝材料来处理选定的土壤，以改善其机械性能。选择包括塌陷势，单轴抗压强度，压缩弹性模量，直接拉伸强度和拉伸弹性模量的土壤特性作为改进的目标参数。在处理之前和之后测量并确定这些参数，并在压缩和拉伸状态下研究处理过的土壤的行为。所得结果表明，纳米和微米级添加剂在压缩和拉伸条件下对处理后的土壤的性能具有不同的影响。