US Patent 7338232 Method for installing a screw pile

A screw pile is equipped with internal grout pipes extending downwardly through the bore of the tubular pile shaft. The grout pipes connect with side-opening ports in the shaft side wall, to form conduits through which fluid grout may be injected into the surrounding ground. The grout is injected at high pressure as the pile is rotatively driven into a sub-surface target formation in which the pile is to be landed. In this way, the grout is distributed along a vertical interval of formation. It has been shown that this technique is characterized by increased load capacities of the implanted pile, relative to piles implanted without grouting or with grouting but only at landed depth.