Abstract: In an underground borer with down hammer having a vehicle body 1, a guide stilt 2 standing on the vehicle body, and a rotary machine 4 having its bottom coupled with a screw shaft 3 and a down hammer B, a supply unit 5 is interposed between the rotary machine 4 and the screw shaft 3, a fluid conduit 6 is formed centrally of the screw shaft 3, compressed air conduits 7 and 7' are formed to surround the fluid conduit 6, and a fluid jetting pipe 8 is arranged centrally of the down hammer B to extend until the inside of a bit body 9 so that water may be discharged, along with high-pressure compressed air, from a central portion of the bottom surface of the bit body during boring to cool the bit body, promote anti-wear properties, suppress powdery dirts, reduce noises and increase the boring speed.

Abstract: There is provided a cement soil apparatus of underground borer capable of improving the efficiency of operation such as pile driving in civil engineering foundation work. A screw shaft 3 and a rotary machine 4 for rotating it are disposed on a guide stilt 2 of a vehicle body 1, a down hammer 6 formed with a screw blade 5 is connected to a lower end of the screw shaft, supply conduits 10, 10' and 11, 11' for cement milk or the like are formed in the screw shaft and the down hammer, respectively, such that the supply conduits in the screw shaft are in communication with those in the down hammer, and valves 12, 12' openable by pressure are disposed in lower end portions of the supply conduits, whereby cement or the like can be supplied from the outside to the inside of a bored hole. When boring operation ends and the down hammer is pulled up, cement milk is grouted.