An underpinning pile assembly for supporting a structure upon the earth has at least one steel pipe with an interior passageway, a concrete pile segment positioned above the steel pipe, and a cable extending through an interior passageway of the steel pipe and through the interior passageway of the concrete pile segment. A locking assembly is connected to the cable and affixed within the steel pipe. This locking assembly includes a collar having an outer surface affixed to an interior wall of the lowermost pipe. The cable is affixed within an interior of the collar. A pair of wedges secure the cable within the interior of the collar.