(1. School of Civil Engineering and Architecture，Northeast Electric Power University，Jilin，Jilin 132012，China；2. College of Architecture and Civil Engineering，Beijing University of Technology，Beijing 100124，China；3. Key Laboratory of Geomechanics and Embankment Engineering，Ministry of Education，Hohai University，Nanjing，Jiangsu 210098，China；4. College of Ocean Science and Engineering，Shanghai Maritime University，Shanghai 201306，China)
Abstract：Helical anchors have been widely used to support the structures suffering from cyclic uplift loading，such as wind turbines and transmission towers，due to their good uplift resistance. And the studies on cyclic performance of helical anchors are limited. Therefore，centrifugal tests of helical anchors(wished-in-place) in dense sand under cyclic loading were conducted to investigate the effects of embedment ratio and number of helices on cyclic uplift stability and cyclic capacity. Test results show that the uplift displacements at the beginning of ultimate cyclic loading level are very close to the failure displacements under monotonic loading for single-helix anchors. Relative ultimate cyclic uplift capacity for single-helix anchor increases gradually with the increase of embedment ratio H/D and reaches the maximum value 0.9 at the embedment ratio of 6，and then the value of almost keeps constant when embedment ratio is more than 6. Moreover，the relative accumulated displacements during each cyclic loading for single-helix anchors with embedment ratio less than 6 are all higher than the anchors with embedment ratio more than 6. Therefore，minimum embedment ratio for single-helix anchor is proposed as 6 when it is used to resist cyclic uplift loading. The relative ultimate cyclic uplift capacity of double-helix anchor is the same as that of single-helix anchor with the same embedment ratio，but the accumulated displacements during each cyclic loading for double-helix anchor are all less than those values for single-helix anchor. Double-helix anchor should have higher cyclic uplift capacity than single-helix anchor if displacement is taken as control condition.
2021, Vol. 40 
