In recent decades, sand columns have been one of the most widely used methods in improving poor soils. Today, sand columns are implemented using different methods and technologies. The main differences between these methods in the construction process are the type of technology, the hardness of the sand columns and the extent of the impact on the surrounding soil around the sand columns. Sand columns (with the exception of the RAP system), although resistant to compressive forces, do not, however, have a suitable mechanism for withstanding the tensile forces due to the application of tensile forces to the building during an earthquake or strong wind. Based on this, the idea presented by Niroumand during 2019-2021 to transform a sand column into a sand column reinforced by injection tube restraints (simple and barbed micropiles), and in general, different dimensions of the problem in several projects. A study was reviewed. The study on this system consists of two parts; determining the pull out capacity of cemented sand columns from inside the soil and determining the pull out capacity of steel micropiles from inside cement sand column.
This study investigates the pull out capacity of various types of steel micropiles from the cement sand column in both laboratory and field sections. Field experiments were conducted in an urban area located on the 530-hectare coastal site of Bushehr port. For this purpose, in the laboratory section, micropiles were made in three types of simple microple (without barbed), micropile with two barbed and micropile with four barbed and buried length of micropiles equal to 75 cm and diameter of micropiles equal to 50 mm. The diameter and length of cemented sand columns were 30 and 75 cm, respectively. In the field section, micropiles were made in three types corresponding to the laboratory. The diameter and nominal length of cemented sand columns were 60 and 480 cm, respectively, and the length of buried piles was 480 cm and diameter of eq