BEHAVIOR OF GROUTED ANCHORS SUBJECTED TO REPEATED LOADINGS IN-FIELD

This paper presents the results of full-scale repeated-loading tests p erformed on three prestressed and six passive anchors grouted to vario us lengths in a rock mass. Different levels of prestress load, ranging from 22% to 73% of the ultimate static load, were applied to the pres tressed anchors. Different levels and amplitudes of repeated loads, ra nging from 10% to 170% of the initial prestress load and from 10% to 7 3% of the ultimate static load, were applied to prestressed and passiv e anchors, respectively. The results have shown that the anchors subje cted to repeated loadings have the same service life as those only sub jected to static loading, provided that the applied repeated loads are less than the initial prestress loads for prestressed anchors, or les s than 30% of the ultimate static loads for passive anchors. Based on this research, it is suggested that grouted anchors subjected to repea ted loadings should be prestressed to loads greater than any likely lo ad fluctuation, and the design capacity of the anchors should be 70% o f the static load holding capacity.