LAUSR

ABSTRACT Vast land areas in northeastern Iran are covered with loess soils being susceptible to collapse and excessive settlement after moistening. Different improvement techniques were developed for loess soils, including compaction, immersion, or reinforcement. However, the shortcomings, such as limited improvement depth and lack of control over the treated area restrict these techniques’ effectiveness. The present study suggests the installation and application of helical piles as a combination of improvement techniques. About 13 uniform triple-helix piles of 3 m length, 250 mm blade diameter, and 750 mm blade spacing were installed via two different dry and wet installation methods. Static pile load tests were performed for all the helical piles. The results showed that the pile load tests were highly dependent on the moisture content at the testing time, the crowd force and the injected water pressure. Eventually, wet installed piles led to a more stable structure of loess soils than dry installed piles subjected to water.