Field Test Study of Long-Term Displacement of Bridge Foundation Subjected to Lateral Loads

Abstract

To investigate the effect of creep characteristics of soft soils on time-dependent deformation of root-caisson foundation, long-term lateral loading tests were performed about 120 days in Wangdong Yangzi River Highway Bridge. The displacement of caisson head, the deformation of the caisson along depth and displacement field of soil ahead the foundation were measured under the constant load. Comparing the short-term deformation and long-term displacement of root-caisson, soil creep effect and time-dependent displacement of foundation are revealed. The results show that deformation of this root-caisson presents characteristic of the flexible foundation. From the entire process the lateral displacement of caisson vs time curve, the horizontal displacement at the top of caisson increases gradually with the continuous time of the constant load, the displacement rising rate declines gradually, and the horizontal displacement finally tends to a stable value. The deformation of the caisson in the holding load stage is larger than the one in the loading stage, the final horizontal displacement of the caisson top is 2–3 times the instantaneous displacement. The rebound displacements of the caisson are small with experiencing a long-term horizontal load after unloading, the creep deformation of the soil occurs under long-term horizontal load.