An apparatus for carrying out bi-directional load testing of close ended driven piles and injection piles utilizing a hydraulic jack, comprising an enclosure for housing the hydraulic jack (13). The enclosure (1) includes a first hollow body (10) a second hollow body (15). The first hollow body (10) had a covered upper end (10a) and an open lower end (10b), with the upper end being capped by an attached top plate (11) having an external surface (11a) which the lower end (81b) of a first pile (81) may be axially attached to, and an internal surface (11b). The open lower end (10b) has a cut-out (12) originating on the edge of the open end (10b) of the first hollow body for receiving a hydraulic connection (14) for the jack (13). The second hollow body (15) is capable of housing the hydraulic jack (13), has an open upper end (15a) and a lower end (15b). The lower end (15b) is capped by an attached base plate (17) having an external surface (17a) which the upper end (82a) of a second pile (82) may be axially attached to, and an internal surface (17b) for attaching the base (13a) of the hydraulic jack, and an opening (16) on the capped lower end (15b) originating at a point where the edge of the lower end (15b) abuts the base plate (17) for receiving the hydraulic connection (14) for the jack. The first hollow body (10) and the second hollow body (15) are capable of axial movement relative to one another when actuated by the hydraulic jack.

Extensible shells and related methods for constructing a support pier are disclosed. An extensible shell can define an interior for holding granular construction material and define a first opening at a first end for receiving the granular construction material into the interior and a second opening at a second end. The extensible shell can be flexible such that the shell expands when granular construction material is compacted in the interior of the shell. A method may include positioning the extensible shell in the ground and filling at least a portion of the interior of the shell with the granular construction material. The granular construction material may be compacted in the interior of the extensible shell to form a support pier.

Embodiments described herein relate to construction of subsurface structural elements that are configured to redirect soil forces. For instance, a form may be used to construct a subsurface structural element such that the subsurface structural element redirects soil forces to vertically displace a foundation rather than have the soil forces crack or otherwise damage the foundation.