Evaluating scale effects and bearing portions in centrifuge modeling of helical anchors: sand

Abstract

Helical anchors are bearing elements that can resist uplift loads by a combination of shaft and helical plate bearing. The application of helical piles as offshore wind turbine foundations has recently become interesting. However, large size of such structures limits the possible physical modeling in a geotechnical centrifuge. In the current study, the limits of physical modeling concerning particle size effect on the uplift capacity of helical piles were evaluated. The modeling of models technique was employed. The contribution of the shaft and helical plate to the anchor uplift capacity was also studied. The results indicate that small ratios of helical plate diameter to shaft diameter lead to higher contribution of the shaft to the total anchor capacity. It was also found that scale effects could be safely ignored if effective helical radius to the mean grain size of the sand is greater than 16. The normalized mobilization distance and dimensionless breakout factor were in good agreement with the previous researches. The limits reported here could contribute to a more reliable physical modeling of helical piles and anchors in the future researches.