Abstract:
Helical anchors offer advantages including convenient construction, high bearing capacity, and reusability; however, research on their rotational installation mechanism in clay soils and the resulting uplift bearing behavior remains limited. Utilizing transparent clay synthesized from fumed silica N20 material and Particle Image Velocimetry (PIV) image processing technology, laboratory model tests on rotational installation and uplift-induced deformation in transparent clay were conducted, complemented by numerical simulation analysis and theoretical derivation of ultimate bearing capacity. The research findings indicate: following rotational installation, soil backflow occurs above the helical plates, while soil subsidence develops beneath the plates upon application of uplift load. The load-displacement curves consistently exhibit an initial steep increase followed by a gradual rise. The ultimate bearing capacity of helical anchors increases with higher embedment depth ratio, greater number of helical plates, larger plate spacing, increased pre-consolidation pressure, and longer setup time after installation, with the influence of setup time exhibiting a critical threshold. The ultimate pullout capacity factor decreases with a reduction in the remoulded interface friction angle ratio (δrem) and an increase in the sensitivity parameter (Xd). The variation pattern of the pullout capacity factor (N) with embedment depth ratio aligns with that observed when installation effects are disregarded, characterized by rapid initial growth followed by stabilization. The ultimate pullout capacity factor derived from a simplified soil failure model demonstrates close agreement with numerical simulation results.