Research on H-3K Creep Coupling Calculation Model of Long-Term Prestress Loss of Anchor Cables

Abstract

Prestress loss of anchor cables can cause a change in the internal force for the support structure of a foundation pit or slope, which may cause engineering accidents. The coupling effect between an anchor cable and the creep of rock and soil is the main factor that leads to the loss of prestress of the anchor cables. However, the traditional Hooke–Kelvin (H-K) viscoelastic model could not accurately predict the long-term loss of prestress. To solve this problem, based on the H-K viscoelastic model, a new H-3K viscoelastic model was proposed, consisting of two generalized Kelvin bodies connected in parallel, and its creep equation and relaxation equation were also derived. Focusing on slope engineering in Longnan City, Gansu Province, China, the prestress of anchor cables calculated by the proposed model were compared with the monitoring data. The result that the H-K creep coupling model is more accurate in predicting prestress loss of anchor cables in the initial stage, but from a long-term perspective, the H-3K creep coupling model provided a more accurate prediction. By connecting more generalized Kelvin bodies in parallel, stress shared by the elastic body can be reduced and stress loss due to anchor cable relaxation can be approximately compensated for to make the prediction results closer to the monitored values. However, when there are more than three Kelvin bodies in parallel, the model prediction results will change only slightly. Therefore, the H-3K creep coupling model is sufficient for practical engineering.