Investigation of the behavior of helical pile subjected to compressive loadings with laboratory and field tests

Helical piles are steel made foundation systems that are placed on the soil by applying torque, can meet various loads such as compression and tensile, are increasingly used in many application areas (offshore, energy structures, industrial structures, etc.) and are also an important alternative to other traditional piles. In this thesis, the behavior of helical piles under axial compression was investigated by laboratory model tests and large-scale field tests. In the tests using sand soil, the effect of different variables such as soil density (Dr), helical plate diameter (D), helical plate number (N), distance between helical plates (s) were examined. In the tests, the torque values applied during the installation of the helical piles into the soil were also evaluated and the effect of the installation torque selection was interpreted. Test results were compared with the theoretical methods in the literature, and also numerically analyzed using finite element method-based software in two- and three-dimensional environments including the disturbance effect. In the tests, the disturbed zone was observed as two times the helix diameter (2D), approximately. An increase in final capacity of up to 30% was achieved with the addition of an extra helix. In the light of these data, various suggestions have been made regarding the design of helical piles in geotechnical engineering.