Numerical and experimental study on influence of installation effects on behaviour of helical anchors in very dense sand

The use of helical anchors has been increasing in recent years; however, the current understanding of its behaviour does not allow for reliable estimates of uplift capacity and load-displacement response. The need for improvement of the design methods has motivated the present study, which investigates the effect of installation on the helical anchor response in very dense sand. This work is divided into three parts. The first part describes the results of centrifuge model tests and microtomographic analysis performed to examine the uplift response of a single-helix anchor and the soil disturbance caused by the installation process. The aim of these tests was to define appropriate hypotheses for the numerical prediction of helical anchor performance. In the second part, the load-displacement curve of a tested helical anchor was numerically simulated with the finite difference software FLAC3D, considering the installation effect observed experimentally. In the third part of the paper, the adjusted numerical model was used in a parametric analysis to provide some guidelines for the design of helical anchors in dense sand. Additionally, from the results of the numerical investigation and experimental observations, two different approaches are presented for improving the accuracy of analytical predictions of helical anchor capacity. Both suggested methods showed good agreement with centrifuge and field testing data.