Loess soils cover approximately 10% of the Earth’s land surface. Due to its honeycomb structure, this soil collapses under pressure and immediately settles when exposed to moisture. Using moisture and loading conditions prior to construction can have positive effects on the geotechnical properties of the soil and help to reduce its settlement. This study aims to investigate the effect of different installation methods of helical piles on microstructure of loess soils. A total number of 16 full-scale helical piles including single helix and double helix piles with spacing to diameter ratios of 1.5 and 3 were installed via wet and dry installation methods. These 3-m-long piles were installed at the site of Inche Borun, Golestan province, northeastern Iran. Pile static load tests were performed on a set of these piles to compare the effect of different installation methods. Furthermore, the behavior of Golestan loess was investigated by removing the soil in front of the other set of helical piles for element testing and SEM imaging. The results suggested that the combination of compressive installation load and water pressure increases the shear strength parameters of Golestan loess and accordingly, the bearing capacity of the installed helical piles.

黄土土壤约占地球陆地表面的10％。由于其蜂窝状结构，这种土壤在压力下会坍塌，并在暴露于湿气时立即沉降。施工前使用水分和负载条件会对土壤的岩土特性产生积极影响，并有助于减少其沉降。本研究旨在探讨螺旋桩不同安装方式对黄土土壤微观结构的影响。通过湿式和干式安装方法安装了总共16个全尺寸螺旋桩，包括单螺旋桩和双螺旋桩，间距与直径之比为1.5和3。这些3米长的桩安装在伊朗东北部Golestan省Inche Borun的现场。在一组这些桩上进行了桩静载荷测试，以比较不同安装方法的效果。此外，通过去除另一组螺旋桩前面的土壤，对哥尔斯坦黄土的行为进行了研究，以进行元素测试和SEM成像。结果表明，压缩安装载荷和水压的组合增加了Golestan黄土的抗剪强度参数，并因此增加了已安装螺旋桩的承载能力。