This paper presents an experimental study on the pullout behaviour of inclined shallow plate anchors subjected to axial pull in sand. The 1g model tests were performed to examine the effects of anchor inclination and sand–anchor interface conditions on the load–displacement response and the associated failure and deformation mechanisms of plate anchors at various embedment ratios and sand densities. The anchor pullout capacity was found to increase continuously with the load inclination angle to the vertical (α), and the increase was more significant for α from 45° to 90°. The effect of sand–anchor interface conditions was negligible for horizontal plate anchors (α = 0°), but it became increasingly significant at larger inclination angles. The effects of these two factors both decreased with an increasing embedment ratio. Their influences on the failure and deformation mechanisms were measured and analysed using a digital image correlation (DIC) technique. Based on the test data and results available in the literature, a simple empirical method for the prediction of pullout resistance of inclined plate anchors in sand is calibrated and recommended.

This paper presents an experimental study on the uplift behaviour of both pipes and strip plate anchors buried in sand. A total of 24 plane-strain uplift tests were performed using an image-based deformation measurement technique, by which the influences of anchor/pipe embedment ratio, sand relative density and pipe roughness on the load-displacement responses and associated failure and deformation mechanisms were systematically investigated. It was observed that the overall uplift responses of pipes and strip anchors were essentially similar. The peak uplift resistance of a strip anchor tended to be greater than that of a pipe at shallow depths, but the difference reduced as the sand-pipe interface frictional strength and the embedment ratio increased. Image analysis shows that the peak resistance of a shallow strip anchor/pipe was mobilised through the formation of an inverted trapezoidal block, bounded between a pair of inclined shear zones. The inclinations of the shear zones were dependent on sand dilatancy, and its average angle to the vertical for a strip anchor is slightly larger than that for a pipe. The shear zones initiate from the edges of an anchor invariably, whereas the initiation points may lie above the pipe waist, varying with sand-pipe interface conditions. These observations were used to modify a limit equilibrium method and a cavity expansion approach for predicting the peak uplift resistance of shallow pipes in sand. The modified methods were validated using a database of 125 shallow pipe uplift tests assembled from the literature. After the modifications, a good agreement with the overall database was shown, with average errors of less than 6%.