Design and construction of helical anchors in soils

Abstract Anchors are structural elements with various civil engineering applications. In general, anchors applied in geotechnical applications can be categorized by different methods. One of the best categories is as follows: (1) grouting anchors and (2) mechanical anchors. Grouting anchors are anchors which need injection of grout and be divided into following categories: (1) strand, (2) bar, and (3) hollow bar. Also, mechanical anchors can be categorized as follows: (1) helical anchors, (2) plate anchors, and (3) direct embedment anchors. Each type of anchors is aimed at transmission of load to a greater depth of the foundation of transmission towers, sea walls, retaining walls, etc., the application of helical anchors is discussed in this chapter. Helical anchor is the type of anchor installed by rotation of its central shaft. Thus it does not need excavation of borehole or trench. The ultimate loading of a helical system can vary based on its number of helices. Generally, increasing the number of helices contributes to increment in the ultimate valence of helical anchors; however, in some cases, disturbance of the soil caused by installation process of helical anchors leads to less ultimate capacity then estimate. In this chapter, helical anchors embedded in sands, clays, and multilayer soils are going to be investigated.