The present invention is an earth-locking apparatus and an inextricably intertwined method to form an underground grid-bridge system to provide foundation support for structures such as sand silos, holding tanks, bulkheads, and power transmission lines. The earth-locking modular apparatus has locking lugs and locking channels perpendicularly connected to a plurality of vanes that extend vertically the length of the central tubular member whereby interlocking vanes are conjoined to multiple modular apparatus allowing for confined compaction of columns and blocks of soil that are then subjected to a porosity destruction process to tighten and de-water the confined soil. The method of completing the underground grid-bridge describes the utilization of the compaction apparatus designed to work in conjunction with the earth-locking modular apparatus and earth-locking compaction implements design-engineered to cause porosity destruction resulting in extreme compression of confined soil to a load-bearing capacity that will resist compression, overturning, uplifting, torsion and sheer.