PURPOSE: To raise the efficiency of operations as well as reduce noise by a method in which after a multispindle auger having a central screw auger and outer screw augers surrounding the central screw auger is penetrated into the ground, the excavated soil surrounded is discharged by the auger by holding.

CONSTITUTION: Outer screw augers 2 are arranged at a given interval around a central screw auger 1, and the upper ends of the augers 1 and 2 are pin-jointed expansively by oil-pressure jacks of two upper and lower stages. An oil-pressure jack is built in the tips 3 of the augers 1 and 2 to make them expandible. After the auger 2 is penetrated into the ground by inclining it inwards, the tip 3 is extended to excavate the ground surrounded by the auger 2. The whole of the multispindle auger is hung up, and the excavated soil 7 is held and discharged. Vibration and noise can be reduced, and the efficiency of excavation can be enhanced.