Uplift capacity of fixed shallow anchors subjected to vertical loading in rock

Abstract

This paper presents the results of full-scale loading tests performed on 54 passive anchors and 4 group-anchored footings grouted to various lengths at several sites in Korea. Various rock types were tested, ranging from highly weathered shale to sound gneiss. In many tests, rock failure was reached and the ultimate loads were recorded along with observations on the shape and extent of the failure surface. Laboratory tests were also conducted to investigate the influence on the bond strength of the corrosion protection sheath. Based on test results, the main parameters governing the uplift capacity of the rock-anchor system were determined. Through evaluation of the ultimate uplift capacity of anchor foundations in a wide range of in situ rock masses, a rock classification suitable for a transmission tower foundation was developed. Finally, a very simple and economical design procedure is proposed for rock-anchor foundations subjected to uplift tensile loads.