Uplift response of strip anchors in sand using FEM

The load displacement relationship of shallow rigid strip anchors embedded in sands and subjected to uplift pressures has been examined by using the finite element method. The soil medium is modeled as a linear elastic-perfect plastic material following Mohr-Coulomb failure criterion and an associated flow rule. The computed load displacement response is presented in non-dimensional form. The ultimate failure load is expressed in the form of non-dimensional uplift factor F, the variation of which is plotted as a function of soil friction angle (phi) and the embedment ratio (lambda) of the anchor. The magnitudes of F-gamma, as well as the displacements of anchor at failure are found to increase with the increases in the values of the anchor embedment ratio and the angle of shearing resistance of soils. In all the cases, it was seen that even at complete collapse, the soil mass lying just vertically above the anchor remains more or less non plastic. The failure of the anchor occurs on account of the development of a thin curved plastic shear zone emerging from the bottom of the anchor and then extending up to the ground surface.