A ground improvement apparatus and the method thereof

A separation type ground piling device and a method of reinforcing a ground using the separation type auger cast piling device are provided to adjust the width of exaction rods depending on the ground layer by individually installing excavation rods to movable driving units fixed on moving blocks installed to guide rods in an auger machine, and to inject compressed air, mortar and accelerator agent selectively into excavated ground by installing inner and outer pipes in each of the excavation rods. A separation type ground piling device has an auger machine(10) vertically lifted or lowered on a crawler crane. Driving units(40) comprises gear boxes(41), decelerators(42), and motors(43) are installed in the auger machine. Excavation rods(20) are individually installed to each of the driving units. Each of the excavation rods have air injection pipes at the centers encased in inner pipes, and mortar or accelerator agent injecting pipes on outer periphery of the inner pipes, and outer pipes encasing all the pipes. Guide bars(12) are installed horizontally in the auger machine. The plural driving units are individually installed to the guide bars. Moving blocks(13) are installed to the guide bars, and the driving units are fixed to the moving blocks. First swivels(50) are installed on upper parts of the gear boxes of driving units to inject the mortar through the center section of driving shafts, and second swivels(51) are installed on upper ends of the excavating rods for injecting the compressed air and the accelerator agent. A method of reinforcing the ground by using the separation type piling device comprises the steps of: investigating the geological state of the ground to be excavated; selecting and adjusting the width of excavation rods based on the findings from the investigation; excavating to the preset depth by adjusting the width of the excavation rods, and by operating an air hammer; filling the mortar and the accelerator into the excavated space through the pipes; and slowly pulling out the excavation rods after the injected mortar and the accelerator agent are mixed with the excavated soil.