Abstract: There is a strong coupling effect between horizontal and vertical direction during inclined drawing of spiral anchor, but its coupling mechanism is not clear yet and lack of quantitative evaluation basis. Circular anchor plate is used to model the single blade screw anchor to carry out inclined drawing model tests in medium-density sand. The inclined drawing bearing mechanism and the influence law of various factors of the flat circular anchor are deeply revealed through the self-made transparent test chamber and digital photographic measurement technology. Some main conclusions are obtained based on the tests. The symmetry of the displacement field and the shear strain field of the soil around the anchor can be divided into two development stages with the change of the load angle. The influence of buried depth ratio on the symmetrical shape of displacement field is more significant than that on shear strain field. With the decrease of load angle, the movement mode of soil around the anchor is gradually transformed from the vertical movement mode in vertical drawing to the rotary movement mode in horizontal drawing, while the two modes coexist in inclined drawing. With the decrease of load angle, the pulling load-bearing displacement curve is transformed from softening type to hardening type. The larger the load angle and buried depth ratio are, the more significant the oscillation of load displacement curve is. Under different buried depth ratios, the three intervals of bearing capacity growth curve have distinct characteristics, which can be fitted by three-stage first-order function. The control degree parameter Cd can reflect the evolution of the control direction with the load angle. When the load angle is in the range of [0°, 80°], the horizontal direction controls the load-bearing characteristics of inclined drawing, while the section of [80°, 90°] is controlled by vertical drawing. The vertical drawing action can significantly improve the horizontal load-bearing capacity of the flat anchors. When judging the load-bearing limit state of the inclined drawing plate anchor or screw anchor, the control direction of the uplift behavior should be determined first.

Key words: circular anchor plate, model test, inclined drawing, ultimate bearing capacity, digital photographic measurement