Comparison of the Performance of Self-Drilled Hollow Bar and Strand Anchors in Soft Soil: A field Study

Abstract

Hollow bars are used increasingly for anchorage applications and have become popular in soil improvement of projects over the use of traditional strand anchors because of their lower construction cost and time. Main factor for soil reinforced with anchors is the pullout resistance. Because little work has been done to investigate the load-deformation behaviour of hollow bar anchors, their bond characteristics in comparison with strand anchors is pending both for developing design codes and construction methods. This study presents a comparison of hollow-bar and strand anchor load-deformation behaviour. A field study was performed by installing full-scale hollow-bars and strand anchors in loose silty sand and subjecting them to pullout testing. The observed load–displacement behaviour indicated that the induced bond diameter of the hollow bar anchors was greater than theoretical calculations and the bond strength estimated for them was larger than the values proposed by existing codes. At a unique bonded and unbonded length, the hollow-bar anchors recorded higher ultimate load than the strand anchors. The bond strength for the hollow-bar anchors was 65–100% greater than for the strand anchors.