Abstract: This invention comprises a technique for constructing concrete foundation columns in underwater locations, wherein the steel casing members used to form the columns may be recovered for subsequent re-use. In the technique, an inner and outer casing are partially imbedded in the ground submerged in the water and in concentric relationship with one another. The annulus formed between said inner and outer casing is filled with unconsolidated sand, while the inner casing is filled with reinforcing material and concrete to form the column. The inner casing is then vibrated at a suitable frequency to reduce the friction between it and the sand and concrete, whereby the inner casing may then be drawn upwardly and from between said concrete and the sand. The sand will then support the concrete until after said concrete has hardened, whereupon the outer casing may then be removed, either by vibration or by conventional techniques.

Abstract: A reaction tie-down system for axially load testing foundation members is provided by removably interconnecting a plurality of high tensile strength bar members from a base plate within a concrete anchor shaft through an adaptor to load-carrying girders. Hydraulic jacks apply an axial load between the foundation shaft which is to be tested and the girders. The reaction force to this axial load is provided by the reaction tie-down system wherein the force is transmitted from the girder through the rods to the anchor shafts and through the anchor shafts to the surrounding soil. The bar members are arranged in a circular pattern for flexibly matching the number of bar members to the anticipated test load. The bar members threadly mate with the base plate and the adaptor and the bar members are removably encased within the concrete anchor shaft by flexible sheaths. All the components are, therefore, reusable except the embedded base plate assembly and flexible sheaths.