Abstract: A series of indoor model tests was conducted to study the sand deformation characteristics around uplift circular plate anchors using digital image correlation technology, with emphasis on the effects of plate diameter, embedment ratio and relative density of sand. The experimental results show that when a same embedment ratio is reached, the peak uplift force and the displacement for the appearance of peak uplift force both increase with increasing plate diameter, yet the uplift bearing capacity coefficient decreases as plate diameter increases. The shape of influence zone concerning soil deformation is not affected by the variation of plate diameter, and this regularity is independent of soil density. For the dense sand case, as embedment ratio increases, the shape of influence zone evolves from a reversed trapezoid to a U shape, and a linear shear failure surface can be captured with the inclination angle of 1/4?p to the vertical, where ?p is the peak friction angle of soil. The surrounded soil exhibits a significant volume expansion due to the uplift of plate anchor in dense sand. For the loose sand case, as embedment ratio increases, the shape of influence zone gradually develops from a rectangle extended into soil surface, to a shell shape embedded within the soil. As to a shallow anchor in loose sand, the shear failure surface of soil perpendicularly progresses from the edge of anchor plate to soil surface. When a deep anchor in loose sand is discussed, an inside oblique shear failure surface can be observed and the inclination angle to the horizontal is about 45°+1/2?p. Irrespective of the embedment ratio, due to the uplift of plate anchor, a small volume expansion zone is observed above the anchor plate, upon which is a large volume contraction zone with the value of volume contraction increasing with the increase of anchor’s embedment ratio.

Key words: digital image correlation technology, circular plate anchor, soil deformation, uplift bearing capacity coefficient