Abstract:
To investigate the group effect of multi-expanded body anchors, continuous spherical expanded anchors were studied through a series of pull-out model tests on anchor groups. Tests were conducted with varying spacing ratios (
S/D= 2, 3, 4), different embedment depths (0.22m, 1.9m, 2.4m), and different arrangement configurations (parallel layout, staggered layout, inclined arrangement). The characteristics of the load-displacement relationship curves during pull-out and the deformation mechanisms of the surrounding soil were analyzed. The influence patterns of different spacings, embedment depths, and arrangement configurations on the group effect were explored. The test results indicate that the embedment depth of the anchor group significantly affects the extent of the soil displacement influence zone around the anchors. Under shallow embedment conditions, the soil displacement influence zone is largest during the elastic stage and gradually decreases thereafter. Under deep embedment conditions, the influence zone is largest during the elastoplastic stage, with subsequent incremental displacement analysis showing a characteristic pattern of initial expansion followed by contraction. Furthermore, adjusting the anchor arrangement configuration can effectively mitigate the negative impact of the group effect on the system's bearing capacity. Taking the case of
S/D= 4 at an embedment depth of 2.4 m as an example: the staggered arrangement reduces lateral disturbance to the bearing capacity of the soil between anchors. Compared to the parallel arrangement, the group effect coefficient increased by 5.3%, and displacement control improved by 18.5%, demonstrating both high bearing capacity and displacement stability. When using inclined arrangements (10°, 20°), the group effect coefficient increased by 2.94% and 5.15%, respectively.