PURPOSE: To slacken sufficiently the ground widely from a pipe wall and to make it possible to insert and fix a round pipe thereinto without environmental pollution by distributing and inclining pipe ends split along the axis to the inside and the outside of the pipe wall alternately, and forming serrated crushing teeth.

CONSTITUTION: All or part of pipe ends split along the axis or part remaining unnotched are twisted to project one end of each of them and the other end respectively to the outside and the inside, and they are distributed and inclined alternately to the inside and the outside of a pipe wall to form serrated crushing teeth. It is desirable that the crushing teeth are formed in imitation of specifications of various kinds of serrated teeth. In addition, the crushing teeth can be projected forward from the pipe ends and inside and outside of the pipe wall. Or, the crushing teeth are arranged on a blocking plate on the front end of a round pipe in the shape of a spiral, and plate-like projections projecting the tail sections to the outside of the pipe can be provided. The ground can be sawed by the projections with the rotation of the pipe, and the pipe is driven forward smoothly in the ground in order to slacken sufficiently the ground widely from the pipe wall. In the case the pipe stands still, it is sufficiently fixed to the ground widely.