Axial compressive behavior of wavy-shaped micropiles in sandy soils: an experimental investigation

Conventional micropiles generally depend on shaft resistance; however, their capacity may be limited, motivating improved geometries to enhance axial performance. This research investigates the enhancement of novel wavy-formed micropiles relative to standard micropiles under axial compressive loading. Small-scale laboratory tests were conducted at diverse sand relative densities: 30%, 60%, and 80%. Parametric studies examined the influences of wavy-bulge diameter, spacing, length, and position. The results show that increasing the diameter of the wavy bulges and reducing the spacing between them have the greatest effects on improving the axial response, followed by placing the wavy bulges at the bottom of the micropile and decreasing their length. The improvement factor (IF) was presented to evaluate axial performance, reaching 2.08 for a wavy bulge diameter ratio of 2.2 and 1.54 for continuous wavy bulges. Geometric modifications have a greater impact in loose than dense sands due to greater confinement by wavy bulges.