Abstract: A self-made visual test device was used to carry out pullout model test of circular anchor plate, and the displacement and deformation fields of the soil around anchor plate were measured and analyzed in the limit state based on the digital photographic measurement technology. Under the test conditions, the ultimate bearing capacity increases nonlinearly with the increase of buried depth ratio, but the growth rate slows down gradually. The observed area surrounded by the soil sliding surface, the ground surface and the anchor plate present an inverted trumpet shape of “large bottom, small top, and long sliding surface”. The sliding surface can be approximated by two straight segments. The ultimate pullout mechanical model consists of an inverted trapezoidal cylinder with a small upper section and a large lower section and an equal-section cylinder. Based on the limit equilibrium conditions, an approach to calculating the ultimate bearing capacity of a shallow circular anchor plate in sand is developed. The calculated results of the four sets of test data by this method are closer to the measured values than by the other four methods, and the dispersion is smaller.

Key words: shallow circular anchor plate, model test, sliding surface, ultimate bearing capacity, digital photographic measurement