Field Tests on Screw Micropiles Under Axial Loading

Screw micropiles consist of a steel tubular shaft with continuous spiral threads, and a threaded tapered segment at the bottom. They have some notable advantages over conventional micropiles: grouting is not required; they are quick to install and immediately loadable, easy to dismantle and reusable; no earthwork is required prior to installation and damage to the soil is minimal after removal; because the installation equipment is small, they are suitable where the access is limited. Although these piles are potentially useful in many applications as well as being environment-friendly, research on their behavior is limited. The paper presents an ongoing experimental study on the axial response of screw piles. A test site in Cornovecchio (Lodi, Italy) was selected and characterized by means of in situ and laboratory tests. A number of field tests of full—scale micropiles, with diameter varying from 66 to 114 mm and length varying from 0.8 to 1.6 m, were undertaken to investigate the piles’ capacity under axial tensile and compressive loads in predominantly cohesive soils.