Study on the Enhancement Effect and Design Method of Grouted Screw Anchors in Mucky Soils

Abstract

Screw anchor foundations are widely used in wind power and power transmission projects owing to their fast construction speed and low construction difficulty. However, their widespread application is constrained by their low bearing capacity per anchor and poor corrosion resistance when buried underground. To address these issues, this study conducted field experiments on six ungrouted screw anchor (UGSA) foundations and six grouted screw anchor (GSA) foundations in mucky soil, obtained Q–w curves, depth-torque curves, and surface displacement‒load curves for UGSAs and GSAs. The study also analyzed the effects of grouting uplift and the presence of cracks in screw anchor foundations. The results show that the grouting uplift effect is optimal for small-diameter screw anchor rods, reaching 58.49%, and the depth-to-diameter ratio has a minor impact on the bearing capacity of GSAs but significantly affects UGSAs. Additionally, the torque coefficient of GSAs is greater than that of UGSAs and decreases with increasing anchor rod diameter. Furthermore, the failure modes of UGSAs and GSAs were observed based on surface crack observations. Finally, based on the UGSAs design formula, a design formula for GSAs is proposed.