Investigating the Effect of Grout on Improving the Performance of Helical Anchors Used in Wall Stabilization

Abstract

The benefits of helical anchors have made them a good alternative to grouted soil anchors. However, as their bearing capacity depends on the length and number of helices, they are not economically justified or feasible in some projects. In this research, an attempt was made to propose a new method of implementing helical anchors and their application considering the advantages of helical and grouted anchors. This method, which was named “grouted helical anchor,” was tested in wet sandy soil. Since one of the most important parameters of anchor design is pull-out resistance, the parameters affecting the pull-out resistance of grouted helical anchor such as overburden pressure, helical anchor configuration, and grout were evaluated to determine the best conditions for constructing an anchor. The results show that in the helical anchor with a 100-mm helix, changing the helix spacing from 300 to 400 mm at 90 kPa increases the maximum pull-out force by less than 6%. At the same overburden pressure, if the helix spacing is 400 mm and the helix diameter is changed from 100 to 130 mm, the maximum pull-out force will increase by more than 29%. However, by injecting and modifying the anchor to the grouted helical anchor, the maximum pull-out force can be increased by more than 45%. Therefore, injection operations can help to increase the pull-out capacity of the helical members without changing their configuration.