Helical Piers

Helical piers consist of circular steel plates deformed in a helix configuration and welded to either a solid square bar or a pipe. The initial or lead section may include a single helix or multiple helix. Extensions can be added to advance the helices to a suitable bearing stratum. Extensions may or may not also include helices. 

The helices act like circular spread footings and capacity is developed at each of the helices. Skin friction along the square bar or pipe is not considered and pile capacity is not gained between the helices. 

Advantages to other foundation types are low noise; relatively small equipment can install and grouting is not required. It is not necessary to wait for grout to cure to apply loads as with other foundation types. 

Disadvantages ar that helical piers only increase significantly in capacity if soil conditions through which they are install improves or more helices are added, since skin friction is not considered. Also helical piers can hang up in hard layers like cobbles without achieving capacity. 

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